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Volume 10
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Plants, Volume 10, Issue 2 (February 2021) – 236 articles

Cover Story (view full-size image): The number of grown seminal roots varies in different wheat accessions and is regulated by environmental factors. Plant hormone jasmonate, endogenously produced or exogenously applied, specifically regulates the development of sixth seminal root during early seedling development. This regulatory effect strongly depends on the jasmonate concentration, the duration of the exposure to the hormone, and ontological history of seeds. The larger number of seminal roots results in a larger root surface area, longer root system, greater root biomass, and is associated with improved tolerance to conditions of water and nutrient deficiency. View this paper
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17 pages, 2128 KiB  
Article
Foliar Application of Zinc Oxide Nanoparticles Promotes Drought Stress Tolerance in Eggplant (Solanum melongena L.)
by Wael M. Semida, Abdelsattar Abdelkhalik, Gamal. F. Mohamed, Taia A. Abd El-Mageed, Shimaa A. Abd El-Mageed, Mostafa M. Rady and Esmat F. Ali
Plants 2021, 10(2), 421; https://doi.org/10.3390/plants10020421 - 23 Feb 2021
Cited by 212 | Viewed by 11686
Abstract
Water shortage and salinity are major challenges for sustaining global food security. Using nutrients in the nano-scale formulation including zinc oxide nanoparticles (ZnO NP) is a novel fertilization strategy for crops. In this study, two field-based trials were conducted during 2018 and 2019 [...] Read more.
Water shortage and salinity are major challenges for sustaining global food security. Using nutrients in the nano-scale formulation including zinc oxide nanoparticles (ZnO NP) is a novel fertilization strategy for crops. In this study, two field-based trials were conducted during 2018 and 2019 to examine the influence of three ZnO NP concentrations (0, 50, and 100 ppm) in eggplant grown under full irrigation (100 of crop evapotranspiration; ETc) and drought stress (60% of ETc). Plant growth, yield, water productivity (WP), physiology, biochemistry, and anatomy responses were evaluated. Drought stress significantly decreased membrane stability index (MSI), relative water content (RWC), and photosynthetic efficiency, thus hampered eggplant growth and yield. In contrast, exogenous ZnO NP to water-stressed eggplant resulted in increased RWC and MSI associated with improved stem and leaf anatomical structures and enhanced photosynthetic efficiency. Under drought stress, supplementation of 50 and 100 ppm ZnO NP improved growth characteristics and increased fruit yield by 12.2% and 22.6%, respectively, compared with fully irrigated plants and nonapplied ZnO NP. The highest water productivity (WP) was obtained when eggplant was irrigated with 60% ETc and foliarly treated with 50 or 100 ppm of ZnO NP, which led to 50.8–66.1% increases in WP when compared with nontreated fully irrigated plants. Collectively, these findings demonstrated that foliar spraying ZnO NP gives the utility for alleviating drought stress effects on eggplant cultivated in saline soil. Full article
(This article belongs to the Special Issue The Impacts of Anthropogenic Environmental Changes on the Antioxidative Systems in Crops)
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<p>TEM image of ZnO nanoparticles (ZnO NP).</p> Full article ">Figure 2
<p>Regression analysis between concentrations of ZnO nanoparticles (ZnO NP) and fruit yield (t ha<sup>−1</sup>) of eggplant.</p> Full article ">Figure 3
<p>Transverse section in eggplant stem as influenced by foliar application with ZnO nanoparticles (ZnO NP) under full (FI) and deficit (DI) irrigation. (<b>a</b>) FI × ZnO NP<sub>(0)</sub>, (<b>b</b>) FI × ZnO NP<sub>(50)</sub>, (<b>c</b>) FI × ZnO NP<sub>(100)</sub>, (<b>d</b>) DI × ZnO NP<sub>(0)</sub>, (<b>e</b>) DI × ZnO NP<sub>(50)</sub>, (<b>f</b>) DI × ZnO NP<sub>(100)</sub>. Scale bar = 350 μm. (cx = cortex, vc = vascular cylinder, pi = pith).</p> Full article ">Figure 4
<p>Transverse section in eggplant leaf as influenced by foliar application with ZnO nanoparticles (ZnO NP) under full (FI) and deficit (DI) irrigation. (<b>a</b>) FI × ZnO NP<sub>(0)</sub>, (<b>b</b>) FI × ZnO NP<sub>(50)</sub>, c: FI × ZnO NP<sub>(100)</sub>, (<b>d</b>) DI × ZnO NP<sub>(0)</sub>, (<b>e</b>) DI × ZnO NP<sub>(50)</sub>, (<b>f</b>) DI × ZnO NP<sub>(100)</sub>. Scale bar = 350 μm. (lb = leaf blade, vb = vascular bundle).</p> Full article ">
24 pages, 3644 KiB  
Article
A New Controlled Release System for Propolis Polyphenols and Its Biochemical Activity for Skin Applications
by Eleni Spanidi, Athanasios Karapetsas, Georgia-Persephoni Voulgaridou, Sophia Letsiou, Nektarios Aligiannis, Ilias Tsochantaridis, Spyridon Kynigopoulos, Maria Lambropoulou, Ioannis Mourtzinos, Aglaia Pappa and Konstantinos Gardikis
Plants 2021, 10(2), 420; https://doi.org/10.3390/plants10020420 - 23 Feb 2021
Cited by 16 | Viewed by 4653
Abstract
Propolis is a resinous substance produced by bees that exhibits antimicrobial, immunostimulatory and antioxidant activity. Its use is common in functional foods, cosmetics and traditional medicine despite the fact that it demonstrates low extraction yields and inconsistency in non-toxic solvents. In this work, [...] Read more.
Propolis is a resinous substance produced by bees that exhibits antimicrobial, immunostimulatory and antioxidant activity. Its use is common in functional foods, cosmetics and traditional medicine despite the fact that it demonstrates low extraction yields and inconsistency in non-toxic solvents. In this work, a new encapsulation and delivery system consisting of liposomes and cyclodextrins incorporating propolis polyphenols has been developed and characterized. The antioxidant, antimutagenic and antiaging properties of the system under normal and UVB-induced oxidative stress conditions were investigated in cultured skin cells and/or reconstituted skin model. Furthermore, the transcript accumulation for an array of genes involved in many skin-related processes was studied. The system exhibits significant polyphenol encapsulation efficiency, physicochemical stability as well as controlled release rate in appropriate conditions. The delivery system can retain the anti-mutagenic, anti-oxidative and anti-ageing effects of propolis polyphenols to levels similar and comparable to those of propolis methanolic extracts, making the system ideal for applications where non-toxic solvents are required and controlled release of the polyphenol content is desired. Full article
(This article belongs to the Special Issue Nanotechnological or Innovative Formulation Approaches for Efficient Delivery of Plant Ingredients)
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<p>Control release of antioxidant activity (DPPH) and total phenolic compounds (TPC) of CRPP for time 0 to 48 h. The results are shown as the mean ± SD of three measurements.</p> Full article ">Figure 2
<p>Cytotoxicity profile of CRPP on human immortalized keratinocyte (HaCat) cells. HaCat cells were incubated for 72 h with increasing concentrations (0%–5%) of CRPP and their cell viability was estimated via sulforhodamine B (SRB) assay. The EC<sub>50</sub> and EC<sub>10</sub> values (efficient concentration that causes 50% and 10% decrease in cell viability, respectively) of CRPP were determined from the dose-response curves. The results are shown as the mean ± SD of three independent experiments.</p> Full article ">Figure 3
<p>Intracellular levels of ATP (LUs). NDHF cells were incubated for 48 h with three different concentrations (0.01%, 0.1% and 1%) of CRPP. The results are shown as the mean ± SD of three independent experiments. *—<span class="html-italic">p</span> ≤ 0.05, significantly different from untreated cells.</p> Full article ">Figure 4
<p>CRPP protects HaCat cells from UVB-induced DNA and protein oxidative damage. (<b>A</b>) HaCat cells were UVB-irradiated for 12 s (55 mJ/cm<sup>2</sup>) or left untreated. Irradiated and non-irradiated cells were incubated for 16 h either with 0.1% CRPP or with normal culture medium alone, and then subjected to single cell gel electrophoresis assay (Comet assay). The scored arbitrary units (AU) represent the extent of DNA damage in the untreated, the UVB-irradiated, the CRPP-treated and the UVB-irradiated and CRPP-treated cells. (<b>B</b>) protein oxidative damage was estimated by measuring the protein carbonyl levels of the untreated, the UVB-irradiated and the UVB-irradiated and CRPP-treated cells with a 2,4-dinitrophenylhydrazine (DNPH) colorimetric assay. The concentration of the protein carbonyls was determined, adjusted to the total protein concentration and expressed as fold change compared to the untreated cells. The data presented are the mean ± SD of three independent experiments performed in duplicates. * <span class="html-italic">p</span> ≤ 0.05, significantly different from the UVB-irradiated cells.</p> Full article ">Figure 5
<p>Intracellular levels of ATP (LUs) under UVB irradiation. Primary human dermal fibroblasts (NHDF) cells were UVB-irradiated for 20 min, at UVB irradiation (0.3 J/cm<sup>2</sup>) or left untreated. Prior to irritation cells were incubated for 48 h either with 1% CRPP or with normal culture medium alone, and then subjected to ATP assay to assess cell viability. The data presented are the mean ± SD of three independent experiments performed in duplicates. *—<span class="html-italic">p</span> ≤ 0.05, significantly different from the UVB-irradiated cells.</p> Full article ">Figure 6
<p>Expression analysis of candidate genes in the presence and absence of 1% v/v CRPP in NHDF cells. Transcript levels of genes encoding proteins, tumor necrosis factor (TNFα) human aquaporin-3 (AQP3), interleukin-4 (Il-4), vascular endothelial growth factor A (VEGFα) and integrin subunit beta 2 (ITGB2) are showed. Data corresponds to the mean ± SEM of at least three independent experiments. Gene expression levels were normalized in relation to intact cells and using the geometric mean of two reference genes (βactin and glyceraldehyde-3-phosphate dehydrogenase (GADPH)). * denote significantly different from untreated NHDF cells (control) of <span class="html-italic">p</span> &lt; 0.05 (two tailed unpaired student t-test), respectively.</p> Full article ">Figure 7
<p>Assessment of the protective effect of CRPP against UVB-induced skin damage. EpidermTM EPI-200 reconstituted skin tissues were treated in the apical surface with 0.1% of CRPP (diluted in assay culture medium) for 2 h, washed with PBS and then exposed to 55 mJ/cm<sup>2</sup> of UVB irradiation. After UVB exposure, the apical surface of the tissues was incubated with CRPP for 2 h and then washed with PBS. After 24 h, the tissues were harvested and sections were taken. Representative figures of eosin and hematoxylin staining of untreated tissues (<b>A</b>), UVB-irradiated skin tissues (<b>B</b>) and tissues exposed to UVB and CRPP (<b>C</b>). Magnification × 400. (<a href="#plants-10-00420-f007" class="html-fig">Figure 7</a>A,B are shared images with the respective images, <a href="#plants-10-00420-f006" class="html-fig">Figure 6</a>A in Karapetsas et al., 2019 [<a href="#B43-plants-10-00420" class="html-bibr">43</a>] and <a href="#plants-10-00420-f005" class="html-fig">Figure 5</a>B in and Karapetsas et al., 2020 [<a href="#B53-plants-10-00420" class="html-bibr">53</a>] under the common funded project “Greece-China Bilateral R&amp;D Cooperation 2013-2015” NSFR grant; Project Nr. 12CHN167).</p> Full article ">Figure 8
<p>Treatment with CRPP leads to a decrease of the UVB-induced mRNA levels of metalloproteinases (MMPs) in a reconstituted skin model. EpidermTM EPI-200 skin tissues were pretreated with 0.1% CRPP, UVB irradiated (55 mJ/cm<sup>2</sup>) and again incubated with CRPP for 2 h. After 24 h, the tissues were harvested and total RNA was extracted. For the quantification of MMP-1, MMP-3, MMP-7 and MMP-9 mRNA levels in the untreated, the UVB-irradiated and the UVB-CRPP treated skin tissues, real-time PCR was performed. The expression levels of MMP-1, MMP-3, MMP-7 and MMP9 were normalized to those of b-actin. Untreated cells served as reference sample. Each reaction was performed in triplicates. For the relative quantification the formula RQ = 2<sup>-ΔΔCt</sup> was used. Representative graphs of two independent experiments. * <span class="html-italic">p</span> ≤ 0.05, ** <span class="html-italic">p</span> ≤ 0.01, *** <span class="html-italic">p</span> ≤ 0.001 significantly different from the UVB-irradiated cells.</p> Full article ">Figure 9
<p>CRPP causes decrease of UVB-induced upregulation of MMPs in a reconstituted skin model. EpidermTM EPI-200 skin tissues were pretreated with 0.1% CRPP for 2 h, UVB irradiated (55 mJ/cm<sup>2</sup>) and again incubated with CRPP for 2 h. After 24 h, the tissues were harvested, sections were taken and immunostaining was performed to detect UVB-induced MMP-1 (<b>A</b>–<b>C</b>), MMP-3 (<b>D</b>–<b>F</b>), MMP-7 (<b>G</b>–<b>I</b>) and MMP-9 (<b>J</b>–<b>L</b>) positive cells. Representative figures at 400× magnification of untreated skin tissues (A,D,G,J), UVB-irradiated skin (B,E,H,K) and UVB and CRPP treated tissues (C,F,I,L). (Subfigures 9B,D,H,K are shared images with the respective images 8B,E,J,N in Karapetsas et al., 2019 [<a href="#B43-plants-10-00420" class="html-bibr">43</a>]. Subfigures 9A,E,G,J are shared images with the respective images 7A,F,I,M in Karapetsas et al., 2020 [<a href="#B53-plants-10-00420" class="html-bibr">53</a>]. Both studies including the current one, were under the common funded project “Greece-China Bilateral R&amp;D Cooperation 2013–2015” NSFR grant; Project Nr. 12CHN167).</p> Full article ">Figure 10
<p>Cell viability levels expressed as mean ± SEM based on reconstituted skin model for: Reconstituted skin model treated with a cosmetic formulation with 1% CRPP and 1% triton-100 as negative control (NC). *—<span class="html-italic">p</span> &lt; 0.05 significantly different from the formulation.</p> Full article ">
31 pages, 989 KiB  
Perspective
Potassium Control of Plant Functions: Ecological and Agricultural Implications
by Jordi Sardans and Josep Peñuelas
Plants 2021, 10(2), 419; https://doi.org/10.3390/plants10020419 - 23 Feb 2021
Cited by 239 | Viewed by 15118
Abstract
Potassium, mostly as a cation (K+), together with calcium (Ca2+) are the most abundant inorganic chemicals in plant cellular media, but they are rarely discussed. K+ is not a component of molecular or macromolecular plant structures, thus it [...] Read more.
Potassium, mostly as a cation (K+), together with calcium (Ca2+) are the most abundant inorganic chemicals in plant cellular media, but they are rarely discussed. K+ is not a component of molecular or macromolecular plant structures, thus it is more difficult to link it to concrete metabolic pathways than nitrogen or phosphorus. Over the last two decades, many studies have reported on the role of K+ in several physiological functions, including controlling cellular growth and wood formation, xylem–phloem water content and movement, nutrient and metabolite transport, and stress responses. In this paper, we present an overview of contemporary findings associating K+ with various plant functions, emphasizing plant-mediated responses to environmental abiotic and biotic shifts and stresses by controlling transmembrane potentials and water, nutrient, and metabolite transport. These essential roles of K+ account for its high concentrations in the most active plant organs, such as leaves, and are consistent with the increasing number of ecological and agricultural studies that report K+ as a key element in the function and structure of terrestrial ecosystems, crop production, and global food security. We synthesized these roles from an integrated perspective, considering the metabolic and physiological functions of individual plants and their complex roles in terrestrial ecosystem functions and food security within the current context of ongoing global change. Thus, we provide a bridge between studies of K+ at the plant and ecological levels to ultimately claim that K+ should be considered at least at a level similar to N and P in terrestrial ecological studies. Full article
(This article belongs to the Section Plant Ecology)
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Figure 1

Figure 1
<p>Schematic of the role of K<sup>+</sup> in plant antistress responses. The transcriptional and post-transcriptional control of K<sup>+</sup> passive and active membrane transporters is a central topic of current research, owing to their important role in plant development, functionality, and control of responses to environmental stresses that they activate. However, several other parallel stress mechanisms allow K<sup>+</sup> replenishment and, thus, enhance stress tolerance. Further, external or internal stimuli (e.g., drought, changes in cellular osmotic pressure or pH, changes in metabolite concentrations, or excess light or oxidation) mediate responses by activating genes encoding hormones and/or proteins that can catalyze the transcription of genes that produce high-affinity K<sup>+</sup> channels. An adequate supply of potassium allows a reduction of carbohydrates in leaf cells by counterbalance mechanisms between K<sup>+</sup> and organic osmolites in cells. Carbohydrates, mostly in terms of hexose content, are decreased in leaves due to a sufficient K<sup>+</sup> supply and transported to another plant organ, owing to better phloem activity. AKT2 transporters can operate in mode 1 as an inward-rectifying channel, or as mode 2 as a nonrectifying channel.</p> Full article ">Figure 2
<p>Schematic of the K<sup>+</sup> uptake and transport in plants, with special attention paid to the potassium battery. The main functions are depicted in green rectangles.</p> Full article ">
18 pages, 3406 KiB  
Article
Isolation and Functional Characterization of the Promoters of Miltiradiene Synthase Genes, TwTPS27a and TwTPS27b, and Interaction Analysis with the Transcription Factor TwTGA1 from Tripterygium wilfordii
by Yanbo Huo, Bin Zhang, Ling Chen, Jing Zhang, Xing Zhang and Chuanshu Zhu
Plants 2021, 10(2), 418; https://doi.org/10.3390/plants10020418 - 23 Feb 2021
Cited by 12 | Viewed by 3085
Abstract
Miltiradiene synthase (MS) genes, TwTPS27a and TwTPS27b, are the key diterpene synthase genes in the biosynthesis of triptolide, which is an important medicinally active diterpenoid in Tripterygium wilfordii. However, the mechanism underlying the regulation of key genes TwTPS27a/b in triptolide biosynthesis [...] Read more.
Miltiradiene synthase (MS) genes, TwTPS27a and TwTPS27b, are the key diterpene synthase genes in the biosynthesis of triptolide, which is an important medicinally active diterpenoid in Tripterygium wilfordii. However, the mechanism underlying the regulation of key genes TwTPS27a/b in triptolide biosynthesis remains unclear. In this study, the promoters of TwTPS27a (1496 bp) and TwTPS27b (1862 bp) were isolated and analyzed. Some hormone-/stress-responsive elements and transcription factor (TF) binding sites were predicted in both promoters, which might be responsible for the regulation mechanism of TwTPS27a/b. The β-glucuronidase (GUS) activity analysis in promoter deletion assays under normal and methyl jasmonate (MeJA) conditions showed that the sequence of −921 to −391 bp is the potential core region of the TwTPS27b promoter. And the TGACG-motif, a MeJA-responsive element found in this core region, might be responsible for MeJA-mediated stress induction of GUS activity. Moreover, the TGACG-motif is also known as the TGA TF-binding site. Yeast one-hybrid and GUS transactivation assays confirmed the interaction between the TwTPS27a/b promoters and the TwTGA1 TF (a MeJA-inducible TGA TF upregulating triptolide biosynthesis in T. wilfordii), indicating that TwTPS27a/b are two target genes regulated by TwTGA1. In conclusion, our results provide important information for elucidating the regulatory mechanism of MS genes, TwTPS27a and TwTPS27b, as two target genes of TwTGA1, in jasmonic acid (JA)-inducible triptolide biosynthesis. Full article
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<p>Putative <span class="html-italic">cis</span>-regulatory elements present in the <span class="html-italic">TwTPS27a</span> promoter (<b>A</b>) and the <span class="html-italic">TwTPS27b</span> promoter <span class="html-italic">(</span><b>B</b>) using the PLACE and PlantCARE databases. Numbers indicate the positions relative to the transcription start site (TSS, assigned as position +1, with a box). Putative CAAT-box elements are shown in shaded. Underlined and overlined sequences represent predicted <span class="html-italic">cis</span>-regulatory elements.</p> Full article ">Figure 2
<p>Activity analysis of the full-length promoter of <span class="html-italic">TwTPS27a/b</span> and a series of 5′-deletion fragments of the <span class="html-italic">TwTPS27b</span> promoter in transiently transformed tobacco plants under normal and MeJA treatment conditions. (<b>A</b>) Schematic diagram of the promoter::GUS constructs. Some important <span class="html-italic">cis</span>-regulatory elements are shown in this schematic diagram. The transcription start site (TSS) was defined as +1. The full-length sequence of the <span class="html-italic">TwTPS27a</span> promoter (27aP, −1392~+124, 1496 bp) and a series of 5′-truncated sequences of the <span class="html-italic">TwTPS27b</span> promoter, including 27bP-1 (−1738~+124, 1862 bp), 27bP-2 (−921~+124, 1045 bp), 27bP-3 (−391~+124, 515 bp), 27bP-4 (−91~+124, 215 bp), and 27bP-5 (+14~+124, 111 bp) were fused to the GUS gene to form a series of promoter::GUS constructs. (<b>B</b>) GUS staining was observed in agroinfiltrated tobacco leaves by carrying different promoter::GUS constructs. aP, 27aP::GUS; bP-1, 27bP-1::GUS; bP-2, 27bP-2::GUS; bP-3, 27bP-3::GUS; bP-4, 27bP-4::GUS; bP-5, 27bP-5::GUS. (<b>C</b>) GUS activity of various promoter deletion fragments in transiently transformed tobacco plants under normal and MeJA treatment conditions. Tobacco leaves infiltrated with <span class="html-italic">A. tumefaciens</span> harboring various promoter::GUS constructs were sprayed with 100 μM MeJA or water (as control) 48 h after agroinfiltration. GUS activity was determined 24 h after MeJA or water treatment conditions and was expressed as pmol 4-MU/h/μg protein. The data represent the means ± SD of three independent experiments. Different lower-case letters indicate statistically significant differences at <span class="html-italic">p</span> &lt; 0.05 (Duncan’s multiple range tests). Statistical differences between MeJA treated and normal (control) conditions were determined by Student’s <span class="html-italic">t</span>-test (**, <span class="html-italic">p</span> &lt; 0.01).</p> Full article ">Figure 2 Cont.
<p>Activity analysis of the full-length promoter of <span class="html-italic">TwTPS27a/b</span> and a series of 5′-deletion fragments of the <span class="html-italic">TwTPS27b</span> promoter in transiently transformed tobacco plants under normal and MeJA treatment conditions. (<b>A</b>) Schematic diagram of the promoter::GUS constructs. Some important <span class="html-italic">cis</span>-regulatory elements are shown in this schematic diagram. The transcription start site (TSS) was defined as +1. The full-length sequence of the <span class="html-italic">TwTPS27a</span> promoter (27aP, −1392~+124, 1496 bp) and a series of 5′-truncated sequences of the <span class="html-italic">TwTPS27b</span> promoter, including 27bP-1 (−1738~+124, 1862 bp), 27bP-2 (−921~+124, 1045 bp), 27bP-3 (−391~+124, 515 bp), 27bP-4 (−91~+124, 215 bp), and 27bP-5 (+14~+124, 111 bp) were fused to the GUS gene to form a series of promoter::GUS constructs. (<b>B</b>) GUS staining was observed in agroinfiltrated tobacco leaves by carrying different promoter::GUS constructs. aP, 27aP::GUS; bP-1, 27bP-1::GUS; bP-2, 27bP-2::GUS; bP-3, 27bP-3::GUS; bP-4, 27bP-4::GUS; bP-5, 27bP-5::GUS. (<b>C</b>) GUS activity of various promoter deletion fragments in transiently transformed tobacco plants under normal and MeJA treatment conditions. Tobacco leaves infiltrated with <span class="html-italic">A. tumefaciens</span> harboring various promoter::GUS constructs were sprayed with 100 μM MeJA or water (as control) 48 h after agroinfiltration. GUS activity was determined 24 h after MeJA or water treatment conditions and was expressed as pmol 4-MU/h/μg protein. The data represent the means ± SD of three independent experiments. Different lower-case letters indicate statistically significant differences at <span class="html-italic">p</span> &lt; 0.05 (Duncan’s multiple range tests). Statistical differences between MeJA treated and normal (control) conditions were determined by Student’s <span class="html-italic">t</span>-test (**, <span class="html-italic">p</span> &lt; 0.01).</p> Full article ">Figure 3
<p>Yeast one-hybrid (Y1H) assays showing that TwTGA1 specifically binds to the TGACG-motif present in the <span class="html-italic">TwTPS27a/b</span> promoters. (<b>A</b>) Schematic diagrams of the promoter and mutant promoter fragments in the <span class="html-italic">TwTPS27a</span> (−622~−93, 530 bp) and <span class="html-italic">TwTPS27b</span> (−621~−92, 530 bp) used for the construction of the bait and mutant bait vectors. The yellow diamond represents the TGACG-motif. aPro and bPro are both 530 bp containing two ‘TGACG’ elements, while aPro-m and bPro-m are mutated forms of aPro and bPro (‘TGACG’ mutated to ‘TctCt’ by PCR cloning). (<b>B</b>) Schematic diagrams of the bait, mutant bait, and prey vectors used for Y1H assays. (<b>C</b>) Y1H assays showing the interaction between TwTGA and the TGACG-motif present in the <span class="html-italic">TwTPS27a/b</span> promoters, based on the ability of the transformed yeast strains to grow on SD/−Leu/AbA<sup>300ng/mL</sup> medium with gradient dilution (1/10, 1/100, 1/1000). The transformants grown on SD/−Leu/−AbA plate were used as positive controls for transformants growth. Positive transformants were confirmed by spotting yeast cells onto agar medium of SD/−Leu with 300 ng/mL AbA. These assays were repeated three times with similar results.</p> Full article ">Figure 3 Cont.
<p>Yeast one-hybrid (Y1H) assays showing that TwTGA1 specifically binds to the TGACG-motif present in the <span class="html-italic">TwTPS27a/b</span> promoters. (<b>A</b>) Schematic diagrams of the promoter and mutant promoter fragments in the <span class="html-italic">TwTPS27a</span> (−622~−93, 530 bp) and <span class="html-italic">TwTPS27b</span> (−621~−92, 530 bp) used for the construction of the bait and mutant bait vectors. The yellow diamond represents the TGACG-motif. aPro and bPro are both 530 bp containing two ‘TGACG’ elements, while aPro-m and bPro-m are mutated forms of aPro and bPro (‘TGACG’ mutated to ‘TctCt’ by PCR cloning). (<b>B</b>) Schematic diagrams of the bait, mutant bait, and prey vectors used for Y1H assays. (<b>C</b>) Y1H assays showing the interaction between TwTGA and the TGACG-motif present in the <span class="html-italic">TwTPS27a/b</span> promoters, based on the ability of the transformed yeast strains to grow on SD/−Leu/AbA<sup>300ng/mL</sup> medium with gradient dilution (1/10, 1/100, 1/1000). The transformants grown on SD/−Leu/−AbA plate were used as positive controls for transformants growth. Positive transformants were confirmed by spotting yeast cells onto agar medium of SD/−Leu with 300 ng/mL AbA. These assays were repeated three times with similar results.</p> Full article ">Figure 4
<p>Activation of the <span class="html-italic">TwTPS7a/b</span> promoters by transient overexpression of TwTGA1 in tobacco leaves. (<b>A</b>) Schematic diagrams of the reporter and effector vectors for GUS staining and GUS fluorimetric assays. LB and RB, left and right T-DNA borders. (<b>B</b>) Red fluorescent signals in transiently transformed tobacco leaf. Top panel: bright field; bottom panel: RFP fluorescence. Scale bar: 2000 μm. aP, 27aP::GUS; TwTGA1, 35S::TwTGA1; MES, 2-(N-morpholino)ethanesulfonic acid (MES) buffer. (<b>C</b>) The GUS staining analysis of the infiltrated tobacco leaves. Different combinations of the mixed bacterial suspension were infiltrated into the left and right sides of the midrib in the same tobacco leaves, respectively. a, bacterial suspension harboring 27aP::GUS+EV was infiltrated into the right side of the midrib, while 27aP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. b, bacterial suspension harboring 27aP::GUS+35S::TwTGA1 was infiltrated into the right side of the midrib, while 27aP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. c, bacterial suspension harboring 27bP::GUS+EV was infiltrated into the right side of the midrib, while 27bP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. d, bacterial suspension harboring 27bP::GUS+35S::TwTGA1 was infiltrated into the right side of the midrib, while 27bP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. aP, 27aP::GUS; bP, 27bP::GUS; TwTGA1, 35S::TwTGA1; EV, empty vector; MES, MES buffer. (<b>D</b>) GUS activity analysis showing that TwTGA1 activates the promoters of <span class="html-italic">TwTPS27a/b</span>. The value of relative GUS activity was measured by the ratio of GUS activity in the right side of the midrib to that of the left side of the midrib in the same tobacco leaf. All data presented here are means±SD of three biological replicates, and these assays were repeated at least three times with similar results. Statistical significance was determined using Student’s <span class="html-italic">t</span>-test (**, <span class="html-italic">p</span> &lt; 0.01).</p> Full article ">Figure 4 Cont.
<p>Activation of the <span class="html-italic">TwTPS7a/b</span> promoters by transient overexpression of TwTGA1 in tobacco leaves. (<b>A</b>) Schematic diagrams of the reporter and effector vectors for GUS staining and GUS fluorimetric assays. LB and RB, left and right T-DNA borders. (<b>B</b>) Red fluorescent signals in transiently transformed tobacco leaf. Top panel: bright field; bottom panel: RFP fluorescence. Scale bar: 2000 μm. aP, 27aP::GUS; TwTGA1, 35S::TwTGA1; MES, 2-(N-morpholino)ethanesulfonic acid (MES) buffer. (<b>C</b>) The GUS staining analysis of the infiltrated tobacco leaves. Different combinations of the mixed bacterial suspension were infiltrated into the left and right sides of the midrib in the same tobacco leaves, respectively. a, bacterial suspension harboring 27aP::GUS+EV was infiltrated into the right side of the midrib, while 27aP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. b, bacterial suspension harboring 27aP::GUS+35S::TwTGA1 was infiltrated into the right side of the midrib, while 27aP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. c, bacterial suspension harboring 27bP::GUS+EV was infiltrated into the right side of the midrib, while 27bP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. d, bacterial suspension harboring 27bP::GUS+35S::TwTGA1 was infiltrated into the right side of the midrib, while 27bP::GUS+MES into the left side of the midrib (as the control) in the same tobacco leaf. aP, 27aP::GUS; bP, 27bP::GUS; TwTGA1, 35S::TwTGA1; EV, empty vector; MES, MES buffer. (<b>D</b>) GUS activity analysis showing that TwTGA1 activates the promoters of <span class="html-italic">TwTPS27a/b</span>. The value of relative GUS activity was measured by the ratio of GUS activity in the right side of the midrib to that of the left side of the midrib in the same tobacco leaf. All data presented here are means±SD of three biological replicates, and these assays were repeated at least three times with similar results. Statistical significance was determined using Student’s <span class="html-italic">t</span>-test (**, <span class="html-italic">p</span> &lt; 0.01).</p> Full article ">Figure 5
<p>The proposed model of TwTGA1 TF in regulating the methyl jasmonate (MeJA)-mediated triptolide biosynthesis through the activation of <span class="html-italic">TwTPS27a/b</span>.</p> Full article ">
13 pages, 1769 KiB  
Article
The Effect of Supplementary LED Lighting on the Morphological and Physiological Traits of Miniature Rosa × Hybrida ‘Aga’ and the Development of Powdery Mildew (Podosphaera pannosa) under Greenhouse Conditions
by Bożena Matysiak
Plants 2021, 10(2), 417; https://doi.org/10.3390/plants10020417 - 23 Feb 2021
Cited by 18 | Viewed by 3862
Abstract
We investigated the growth traits, flower bud formation, photosynthetic performance, and powdery mildew development in miniature Rosa × hybrida ‘Aga’ plants grown in the greenhouse under different light-emitting diode (LED) light spectra. Fluorescence-based sensors that detect the maximum photochemical efficiency of photosystem II [...] Read more.
We investigated the growth traits, flower bud formation, photosynthetic performance, and powdery mildew development in miniature Rosa × hybrida ‘Aga’ plants grown in the greenhouse under different light-emitting diode (LED) light spectra. Fluorescence-based sensors that detect the maximum photochemical efficiency of photosystem II (PS II) as well as chlorophyll and flavonol indices were used in this study. Five different LED light treatments as a supplement to natural sunlight with red (R), blue (B), white (W), RBW+FR (far-red) (high R:FR), and RBW+FR (low R:FR) were used. Control plants were illuminated only by natural sunlight. Plants were grown under different spectra of LED lighting and the same photosynthetic photon flux density (PPFD) (200 µmol m−2 s−1) at a photoperiod of 18 h. Plants grown under both RBW+FR lights were the highest, and had the greatest total shoot length, irrespective of R:FR. These plants also showed the highest maximum quantum yield of PS II (average 0.805) among the light treatments. Red monochromatic light and RBW+FR at high R:FR stimulated flower bud formation. Moreover, plants grown under red LEDs were more resistant to Podosphaera pannosa than those grown under other light treatments. The increased flavonol index in plants exposed to monochromatic blue light, compared to the W and control plants, did not inhibit powdery mildew development. Full article
(This article belongs to the Special Issue Applications and Advances in Artificial Light for Horticulture and Crop Production)
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Figure 1
<p>Plant height of <span class="html-italic">Rosa</span> ‘Aga’ after 1, 3, and 6 weeks of growth under six different light-emitting diode (LED) light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR (far-red) with high ratio of red to far-red (R:FR), and S2—RBW + FR with low R: FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 2
<p>Total shoot length per plant of <span class="html-italic">Rosa</span> ‘Aga’ after 1, 3, and 6 weeks of growth under six different light-emitting diode LED light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR with high R:FR, and S2—RBW + FR with low R:FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 3
<p>Number of shoots per plant of <span class="html-italic">Rosa</span> ‘Aga’ after 1, 3, and 6 weeks of growth under six different light-emitting diode LED light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR with high R:FR, and S2—RBW + FR with low R:FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 4
<p>Number of flower buds and flowers per pot of <span class="html-italic">Rosa</span> ‘Aga’ after 1, 3, and 6 weeks of growth under six different light-emitting diode LED light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR with high R:FR, and S2—RBW + FR with low R:FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 5
<p>Changes in chlorophyll <span class="html-italic">a</span> fluorescence parameters—the maximum quantum yield of PSII, represented by F<sub>V</sub>/F<sub>M</sub> (the variable fluorescence F<sub>V</sub> to maximum fluorescence F<sub>M</sub>) in <span class="html-italic">Rosa</span> ‘Aga’ after 1, 3, and 6 weeks under six different light-emitting diode LED light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR with high R:FR, and S2—RBW + FR with low R:FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 6
<p>Chlorophyll content, flavonols, nitrogen balance index (NBI) indices in <span class="html-italic">Rosa</span> ‘Aga’ after 6 weeks of growth under six different light-emitting diode LED light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR with high R:FR, and S2—RBW + FR with low R:FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 7
<p>Powdery mildew severity (0–5-scale) in plants of <span class="html-italic">Rosa</span> ‘Aga’ after 1, 3, and 6 weeks of growth with natural infection in greenhouses, and grown under six different light-emitting diode LED light treatments (Control—unlighted, R—red, B—blue, W—white, S1—RBW + FR with high R: FR and S2—RBW + FR with low R:FR. Average values (<span class="html-italic">n</span> = 30, ±SE) followed by different letters differ significantly according to Tukey’s test (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 8
<p>Spectral photon flux distribution (Y axis: relative values from 0 to 100%) for 340- to 780-nm lighting treatments. Charts in the upper row from left to right: control—sunlight inside greenhouse, R—red. Charts in the middle row from left to right: B—blue, W—white. Charts in the lower row from left to right: S1—RBW + FR with high R:FR and S2—RBW + FR with low R:FR.</p> Full article ">
15 pages, 2319 KiB  
Article
Telomere Length in Norway Spruce during Somatic Embryogenesis and Cryopreservation
by Tuija Aronen, Susanna Virta and Saila Varis
Plants 2021, 10(2), 416; https://doi.org/10.3390/plants10020416 - 23 Feb 2021
Cited by 7 | Viewed by 2710
Abstract
Telomeres i.e., termini of the eukaryotic chromosomes protect chromosomes during DNA replication. Shortening of telomeres, either due to stress or ageing is related to replicative cellular senescence. There is little information on the effect of biotechnological methods, such as tissue culture via somatic [...] Read more.
Telomeres i.e., termini of the eukaryotic chromosomes protect chromosomes during DNA replication. Shortening of telomeres, either due to stress or ageing is related to replicative cellular senescence. There is little information on the effect of biotechnological methods, such as tissue culture via somatic embryogenesis (SE) or cryopreservation on plant telomeres, even if these techniques are widely applied. The aim of the present study was to examine telomeres of Norway spruce (Picea abies (L.) Karst.) during SE initiation, proliferation, embryo maturation, and cryopreservation to reveal potential ageing or stress-related effects that could explain variation observed at SE process. Altogether, 33 genotypes from 25 families were studied. SE initiation containing several stress factors cause telomere shortening in Norway spruce. Following initiation, the telomere length of the embryogenic tissues (ETs) and embryos produced remains unchanged up to one year of culture, with remarkable genotypic variation. Being prolonged in vitro culture can, however, shorten the telomeres and should be avoided. This is achieved by successful cryopreservation treatment preserving telomere length. Somatic embryo production capacity of the ETs was observed to vary a lot not only among the genotypes, but also from one timepoint to another. No connection between embryo production and telomere length was found, so this variation remains unexplained. Full article
(This article belongs to the Special Issue New Insights into Plant Somatic Embryogenesis: Genetic and Epigenetic View)
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<p>Somatic embryo production of 21 embryogenic lines of Norway spruce following 4, 8, or 12 months in continuous proliferation, or following cryopreservation at age of 4 months, thawing, and further proliferation for 2 months, <span class="html-italic">n</span> = 252. Number of embryos produced per gram of fresh weight (gFW) of embryogenic tissue with standard error are shown. The group means that differ significantly from each other (Student–Newman–Keuls multiple range test, <span class="html-italic">p</span> &lt; 0.05) are marked by different letters.</p> Full article ">Figure 2
<p>The length of telomeric repeats in the studied Norway spruce materials including immature zygotic embryos (ZEs), proliferating embryogenic tissues (ETs) and mature somatic embryos (SEs): The 2012 (<span class="html-italic">n</span> = 33) and 2014 materials (<span class="html-italic">n</span> = 85) consisting of different sets of genotypes were studied separately. In the 2012 material, significant differences between 14- and 22-month-old ETs studied with five genotypes are marked by different letters. When examining 12 genotypes of the 2012 material representing ETs continuously proliferated for 14 months or cryostored and proliferated for 14 + 1 months, no significant differences were found. In the 2014 material, no significant differences were found among ETs proliferated for 4, 8, or 12 months or cryostored when compared with each other, nor among SEs derived from different-aged ETs. The 2014 means for sample types (ZEs, ETs, and SEs) that differ significantly (Student–Newman–Keuls multiple range test, <span class="html-italic">p</span> &lt; 0.05) from each other are marked by different letters.</p> Full article ">Figure 3
<p>Southern hybridization showing telomere length in two genotypes of Norway spruce: Samples taken from proliferating embryogenic tissues (ETs) after 4, 8, or 12 months of continuous proliferation, or following cryopreservation (C) at age of 4 months, thawing, and further proliferation for 2 months prior to maturation, as well as mature somatic embryos (SE) originating in the ETs of either 4, 8, or 12 months of age are shown.</p> Full article ">Figure 4
<p>Southern hybridization showing telomere length in proliferating embryogenic tissue of Norway spruce prior to and following cryopreservation: The five genotypes shown on the left panel were cryopreserved both using a method leading to successful regeneration (pretreatment on semisolid media with increasing sucrose concentration, PGD cryoprotectant mixture, and slow cooling in programmable freezer) and by methods resulting in no regeneration (pretreatment in liquid medium and Me2SO as cryoprotectant, or freezing in Mr. Frosty containers at −80 °C), while the seven genotypes shown on the right panel were cryopreserved only using successful method.</p> Full article ">
30 pages, 451 KiB  
Review
Recent Large-Scale Genotyping and Phenotyping of Plant Genetic Resources of Vegetatively Propagated Crops
by Hilde Nybom and Gunārs Lācis
Plants 2021, 10(2), 415; https://doi.org/10.3390/plants10020415 - 23 Feb 2021
Cited by 22 | Viewed by 5744
Abstract
Several recent national and international projects have focused on large-scale genotyping of plant genetic resources in vegetatively propagated crops like fruit and berries, potatoes and woody ornamentals. The primary goal is usually to identify true-to-type plant material, detect possible synonyms, and investigate genetic [...] Read more.
Several recent national and international projects have focused on large-scale genotyping of plant genetic resources in vegetatively propagated crops like fruit and berries, potatoes and woody ornamentals. The primary goal is usually to identify true-to-type plant material, detect possible synonyms, and investigate genetic diversity and relatedness among accessions. A secondary goal may be to create sustainable databases that can be utilized in research and breeding for several years ahead. Commonly applied DNA markers (like microsatellite DNA and SNPs) and next-generation sequencing each have their pros and cons for these purposes. Methods for large-scale phenotyping have lagged behind, which is unfortunate since many commercially important traits (yield, growth habit, storability, and disease resistance) are difficult to score. Nevertheless, the analysis of gene action and development of robust DNA markers depends on environmentally controlled screening of very large sets of plant material. Although more time-consuming, co-operative projects with broad-scale data collection are likely to produce more reliable results. In this review, we will describe some of the approaches taken in genotyping and/or phenotyping projects concerning a wide variety of vegetatively propagated crops. Full article
(This article belongs to the Special Issue Plant Genetic Resources and Breeding of Clonally Propagated Crops)
21 pages, 994 KiB  
Article
Establishment of a Cell Suspension Culture of Eysenhardtia platycarpa: Phytochemical Screening of Extracts and Evaluation of Antifungal Activity
by Antonio Bernabé-Antonio, Alejandro Sánchez-Sánchez, Antonio Romero-Estrada, Juan Carlos Meza-Contreras, José Antonio Silva-Guzmán, Francisco Javier Fuentes-Talavera, Israel Hurtado-Díaz, Laura Alvarez and Francisco Cruz-Sosa
Plants 2021, 10(2), 414; https://doi.org/10.3390/plants10020414 - 23 Feb 2021
Cited by 8 | Viewed by 3837
Abstract
Eysenhardtia platycarpa (Fabaceae) is a medicinal plant used in Mexico. Biotechnological studies of its use are lacking. The objective of this work was to establish a cell suspension culture (CSC) of E. platycarpa, determine the phytochemical constituents by spectrophotometric and [...] Read more.
Eysenhardtia platycarpa (Fabaceae) is a medicinal plant used in Mexico. Biotechnological studies of its use are lacking. The objective of this work was to establish a cell suspension culture (CSC) of E. platycarpa, determine the phytochemical constituents by spectrophotometric and gas chromatography‒mass spectrometry (GC‒MS) methods, evaluate its antifungal activity, and compare them with the intact plant. Friable callus and CSC were established with 2 mg/L 1-naphthaleneacetic acid plus 0.1 mg/L kinetin. The highest total phenolics of CSC was 15.6 mg gallic acid equivalents (GAE)/g dry weight and the total flavonoids content ranged from 56.2 to 104.1 µg quercetin equivalents (QE)/g dry weight. The GC‒MS analysis showed that the dichloromethane extracts of CSC, sapwood, and heartwood have a high amount of hexadecanoic acid (22.3–35.3%) and steroids (13.5–14.7%). Heartwood and sapwood defatted hexane extracts have the highest amount of stigmasterol (~23.4%) and β-sitosterol (~43%), and leaf extracts presented β-amyrin (16.3%). Methanolic leaf extracts showed mostly sugars and some polyols, mainly D-pinitol (74.3%). Compared with the intact plant, dichloromethane and fatty hexane extracts of CSC exhibited percentages of inhibition higher for Sclerotium cepivorum: 71.5% and 62.0%, respectively. The maximum inhibition for Rhizoctonia solani was with fatty hexane extracts of the sapwood (51.4%). Our study suggests that CSC extracts could be used as a possible complementary alternative to synthetic fungicides. Full article
(This article belongs to the Special Issue Biotechnological Approaches for the Production of Bioactives)
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<p>In vitro cultures of <span class="html-italic">Eysenhardtia platycarpa</span>. (<b>A</b>) Plantlets grown in MS culture medium without plant growth regulators; (<b>B</b>) callus production at 15 days of culture; (<b>C</b>) cell suspension cultures with 2 mg/L NAA and 0.5 mg/L KIN; (<b>D</b>) fresh biomass harvested after 12 days of culture; (<b>E</b>) dried biomass used for obtaining extracts.</p> Full article ">Figure 2
<p>Growth kinetics and consumption of sucrose of a cell suspension culture of <span class="html-italic">Eysenhardtia platycarpa</span> for 18 days of culture. Values represent the mean ± standard deviation of three replicates.</p> Full article ">Figure 3
<p>Production of total phenolics (TPH) and total flavonoids content (TFL) of a cell suspension culture of <span class="html-italic">Eysenhardtia platycarpa</span> over 18 days of culture. Values represent the mean ± standard deviation of three replicates.</p> Full article ">Figure 4
<p>Chemical groups summarized by plant extracts resource of <span class="html-italic">E. platycarpa</span>. (<b>A</b>) Fatty hexane extract; (<b>B</b>) defatted hexane extract. Alk: alkanes; Ac: aromatic compounds; Dsa: derivatives from saturated alkanoic acids; Dua: derivatives from unsaturated alkanoic acids; Saa: saturated alkanoic acids; Sd: saturated diacids; Ste: steroids; Tri: triterpenoids; Uaa: unsaturated alkanoic acids; Oth: others. CSC: Cell suspension cultures. Values represent the mean ± standard deviation of two replicates.</p> Full article ">Figure 5
<p>Chemical groups of <span class="html-italic">E. platycarpa</span> extracts, summarized by plant extract source. (<b>A</b>) Dichloromethane extract; (<b>B</b>) methanolic extract. Ac: aromatic compounds; Dsa: derivatives from saturated alkanoic acids; Mod: mono and disaccharides; Poly: polyols; Sd: saturated diacids; Saa: saturated alkanoic acids; Ses: sesquiterpenoids; Ste: steroids; Uaa: unsaturated alkanoic acids; Oth: others. CSC: Cell suspension cultures. Values represent the mean ± standard deviation of two replicates.</p> Full article ">Figure 6
<p>Effect of different source extracts of <span class="html-italic">Eysenhardtia platycarpa</span> on inhibition of mycelial growth of <span class="html-italic">Rhizoctonia solani</span> and <span class="html-italic">Sclerotium cepivorum</span> after 72 h of culture. (<b>A</b>) Fatty hexane extract; (<b>B</b>) defatted hexane extract. CSC: Cell suspension culture. Values represent mean ± standard deviation of three replicates. Bars followed by the same letter between the same fungus are not significantly different (<span class="html-italic">p</span> = 0.05) using Tukey’s multiple range test.</p> Full article ">Figure 7
<p>Effect of different source extracts of <span class="html-italic">Eysenhardtia platycarpa</span> on the inhibition of mycelial growth of <span class="html-italic">Rhizoctonia solani</span> and <span class="html-italic">Sclerotium cepivorum</span> at 72 h of culture: (<b>A</b>) Dichloromethane extract; (<b>B</b>) methanolic extract. CSC: Cell suspension culture. Values represent mean ± standard deviation of three replicates. Bars followed by the same letter between the same fungus are not significantly different (<span class="html-italic">p</span> = 0.05) using Tukey’s multiple range test.</p> Full article ">
23 pages, 6296 KiB  
Article
Discovering Penicillium polonicum with High-Lytic Capacity on Helianthus tuberosus Tubers: Oil-Based Preservation for Mold Management
by Abdulaziz A. Al-Askar, Ehsan M. Rashad, Khalid M. Ghoneem, Ashraf A. Mostafa, Fatimah O. Al-Otibi and WesamEldin I. A. Saber
Plants 2021, 10(2), 413; https://doi.org/10.3390/plants10020413 - 23 Feb 2021
Cited by 18 | Viewed by 3592 | Correction
Abstract
During preservation, Jerusalem artichoke (JA) tubers are subjected to deterioration by mold fungi under storage, which signifies a serious problem. A new blue mold (Penicillium polonium) was recorded for the first time on JA tubers. Penicillium mold was isolated, identified (morphologically, [...] Read more.
During preservation, Jerusalem artichoke (JA) tubers are subjected to deterioration by mold fungi under storage, which signifies a serious problem. A new blue mold (Penicillium polonium) was recorded for the first time on JA tubers. Penicillium mold was isolated, identified (morphologically, and molecularly), and deposited in GenBank; (MW041259). The fungus has a multi-lytic capacity, facilitated by various enzymes capable of severely destroying the tuber components. An economic oil-based procedure was applied for preserving and retaining the nutritive value of JA tubers under storage conditions. Caraway and clove essential oils, at a concentration of 2%, were selected based on their strong antifungal actions. JA tubers were treated with individual oils under storage, kept between peat moss layers, and stored at room temperature. Tubers treated with both oils exhibited lower blue mold severity, sprouting and weight loss, and higher levels of carbohydrates, inulin, and protein contents accompanied by increased levels of defense-related phytochemicals (total phenols, peroxidase, and polyphenol oxidase). Caraway was superior, but the results endorse the use of both essential oils for the preservation of JA tubers at room temperature, as an economic and eco-safe storage technique against the new blue mold. Full article
(This article belongs to the Special Issue Chemical Composition and Antimicrobial Activity of Essential Oils)
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<p>Tubers of Jerusalem artichoke (JA) stored under cooling conditions, showing the healthy (<b>A</b>) and blue mold decayed (<b>B</b>) tubers.</p> Full article ">Figure 2
<p>Colony morphology of <span class="html-italic">P. polonicum</span> on malt extract agar (MEA) medium: (<b>A</b>) obverse and (<b>B</b>), reverse.</p> Full article ">Figure 3
<p>Microscopic micrograph of <span class="html-italic">P. polonicum</span> shows the typical terverticllate conidiophores ((<b>A</b>,<b>B</b>), at ×400) with smooth septate stripes and the spherical conidia ((<b>C</b>), at ×400).</p> Full article ">Figure 4
<p>Disease severity of the three tested isolates of <span class="html-italic">Penicillium polonicum</span> on JA tubers.</p> Full article ">Figure 5
<p>Artificially infected JA tubers with <span class="html-italic">P. polonicum</span> ARS20, showing the healthy (<b>A</b>) and the typical symptoms of blue mold (<b>B</b>) on tubers.</p> Full article ">Figure 6
<p>Molecular phylogenetic tree of the partial sequence of the internal transcribed spacer, showing the position (highlighted with the yellow rectangle) of <span class="html-italic">P. polonicum</span> ARS20 (MW041259) with respect to the closely related sequences obtained from GenBank.</p> Full article ">Figure 7
<p>The growth of <span class="html-italic">P. polonicum</span> (%) as a response to various essential oils concentrations, in relation to control. ND: not determined due to the absence of fungal growth.</p> Full article ">Figure 8
<p>Chromatographic analysis of clove and caraway essential oils, showing the peaks of various components. For clove oil, (1) methyl salicylate, (2) bicyclobutylidiene, (3) eugenol, (4) eugenyl acetate, and (5) farnesene. For caraway oil, (1) limonene, (2) carvone, (3) perilla alcohol, and (4) carveol. Peaks designated with astricts (*) are unidentified compounds.</p> Full article ">Figure 9
<p>Effect of clove and caraway essential oils on control of JA tuber decay caused by <span class="html-italic">P. polonicum</span> under storage conditions at 25 °C after 2 months. (<b>A</b>) = untreated control (C), (<b>B</b>) = untreated and infected by <span class="html-italic">P. polonicum</span> (ARS20), (<b>C</b>) = treated with caraway oil (CR), (<b>D</b>) = treated with clove oil (CL), (<b>E</b>) = treated with caraway oil plus infection by <span class="html-italic">P. polonicum</span> (CRP) and (<b>F</b>) = treated with clove oil plus infection by <span class="html-italic">P. polonicum</span> (CLP).</p> Full article ">Figure 10
<p>Defense-related phytochemicals of JA tubers treated with essential oils and infected with <span class="html-italic">P. polonicum</span> under storage at 25 ± 2 °C (mean ± SD). C: untreated control; P: untreated infection by <span class="html-italic">P. polonicum</span> (ARS20); CR: treated with caraway oil; CL: treated with clove oil; CRP: treated with caraway oil plus infection by <span class="html-italic">P. polonicum</span>; CLP: treated with clove oil plus infection by <span class="html-italic">P. polonicum</span>; ND: not determined due to full deterioration.</p> Full article ">Figure 11
<p>Comparative response features of JA tubers treated with essential oils after infection with <span class="html-italic">P. polonicum</span> under storage at 25 ± 2 °C (mean ± SD). C: untreated control; P: untreated infection by <span class="html-italic">P. polonicum</span> (ARS20); CR: treated with caraway oil; CL: treated with clove oil; CRP: treated with caraway oil plus infection by <span class="html-italic">P. polonicum</span>; CLP: treated with clove oil plus infection by <span class="html-italic">P. polonicum</span>; ND: not determined due to full deterioration.</p> Full article ">Figure 12
<p>Comparative carbohydrates, inulin, and protein contents of JA tubers treated with caraway and clove essential oils and infected with <span class="html-italic">P. polonicum</span> under storage at 25 ± 2 °C (mean ± SD). C: untreated control; P: untreated infection by <span class="html-italic">P. polonicum</span> (ARS20); CR: treated with caraway oil; CL: treated with clove oil; CRP: treated with caraway oil plus infection by <span class="html-italic">P. polonicum</span>; CLP: treated with clove oil plus infection by <span class="html-italic">P. polonicum</span>; ND: not determined due to full deterioration.</p> Full article ">
23 pages, 2979 KiB  
Article
Assessing the Involvement of Selected Phenotypes of Pseudomonas simiae PICF7 in Olive Root Colonization and Biological Control of Verticillium dahliae
by Nuria Montes-Osuna, Carmen Gómez-Lama Cabanás, Antonio Valverde-Corredor, Roeland L. Berendsen, Pilar Prieto and Jesús Mercado-Blanco
Plants 2021, 10(2), 412; https://doi.org/10.3390/plants10020412 - 23 Feb 2021
Cited by 20 | Viewed by 3998
Abstract
Pseudomonas simiae PICF7 is an indigenous inhabitant of the olive (Olea europaea L.) rhizosphere/root endosphere and an effective biocontrol agent against Verticillium wilt of olive (VWO), caused by the soil-borne fungus Verticillium dahliae. This study aimed to evaluate the potential involvement [...] Read more.
Pseudomonas simiae PICF7 is an indigenous inhabitant of the olive (Olea europaea L.) rhizosphere/root endosphere and an effective biocontrol agent against Verticillium wilt of olive (VWO), caused by the soil-borne fungus Verticillium dahliae. This study aimed to evaluate the potential involvement of selected phenotypes of strain PICF7 in root colonization ability and VWO biocontrol. Therefore, a random transposon-insertion mutant bank of P. simiae PICF7 was screened for the loss of phenotypes likely involved in rhizosphere/soil persistence (copper resistance), root colonization (biofilm formation) and plant growth promotion (phytase activity). Transposon insertions in genes putatively coding for the transcriptional regulator CusR or the chemotaxis protein CheV were found to affect copper resistance, whereas an insertion in fleQ gene putatively encoding a flagellar regulatory protein hampered the ability to form a biofilm. However, these mutants displayed the same antagonistic effect against V. dahliae as the parental strain. Remarkably, two mutants impaired in biofilm formation were never found inside olive roots, whereas their ability to colonize the root exterior and to control VWO remained unaffected. Endophytic colonization of olive roots was unaltered in mutants impaired in copper resistance and phytase production. Results demonstrated that the phenotypes studied were irrelevant for VWO biocontrol. Full article
(This article belongs to the Special Issue Biological Control of Plant Diseases)
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<p>Similarity plot of type strain <span class="html-italic">Pseudomonas simiae</span> CCUG 50988<sup>T</sup>, <span class="html-italic">Pseudomonas simiae</span> WCS417 and <span class="html-italic">Pseudomonas simiae</span> PICF7 constructed by using progressive Mauve (see main text, <a href="#sec2dot1-plants-10-00412" class="html-sec">Section 2.1</a>, for color codes).</p> Full article ">Figure 2
<p>Phenotypes altered in selected <span class="html-italic">Pseudomonas simiae</span> PICF7 mutants. (<b>A</b>) Cop1 and Cop33 mutants are unable to grow on LB agar plates supplemented with 4.5 mM CuSO<sub>4</sub><sub>·</sub>5H<sub>2</sub>O (image taken 3 days after bacterial inoculation. (<b>B</b>) Mutants Bfm8 and Bfm9 are defective in producing biofilm. Upper image shows borosilicate tubes containing the bacterial cultures in LB medium. Lower image shows the result obtained after performing the staining procedure with crystal violet and the inner surface-adhered bacteria. (<b>C</b>) Mutants Phy17 and Phy18 are impaired in phytase activity when assayed in Phytase Specific Medium (PSM) (picture taken 3 days after bacterial inoculation). See the Materials and Methods section for full experimental details. PICF7, <span class="html-italic">P. simiae</span> PICF7; KT2440, <span class="html-italic">Pseudomonas putida</span> KT2440. These strains were used as positive controls. PIC128, <span class="html-italic">Pseudomonas indica</span> PIC128 was used as a negative control.</p> Full article ">Figure 3
<p>Schemes representing the Tn5-Tc<sup>R</sup> insertion sites (within genes shown in yellow color) in the genome of the <span class="html-italic">Pseudomonas simiae</span> PICF7 selected mutants. (<b>A</b>), Mutant Cop1; (<b>B</b>), Mutant Cop33; (<b>C</b>), Mutant Bfm8; (<b>D</b>), Mutant Bfm9. The approximate transposon insertion sites are shown as inverted blue triangles.</p> Full article ">Figure 4
<p>Confocal laser scanning microscopy images of root hairs from olive (cv. Picual) internally colonized by GFP-labeled PICF7 mutants. Images are representative of colonization events photographed from 5 to 10 days after root bacterization. Scale bar represents 50 μm in panels (<b>A</b>,<b>B</b>), and 20 μm in panels (<b>C</b>,<b>D</b>). rh, root hair.</p> Full article ">Figure 5
<p>Confocal laser scanning microscopy images of olive (cultivar Picual) roots colonized by GFP-labeled <span class="html-italic">Pseudomonas simiae</span> PICF7 and its selected Tn5-Tc<sup>R</sup> insertion mutants. Images show inner colonization events of different root tissues by wild-type PICF7 (panel (<b>A</b>)), and mutants Cop1 (<b>B</b>), Cop33 (<b>C</b>), Phy17 (<b>D</b>) and Phy18 (<b>E</b>). Additionally, colonization of olive root surface by wild-type PICF7 (panel (<b>F</b>)) and biofilm mutants Bfm8 (<b>G</b>) and Bfm9 (<b>H</b>) are also shown. Images are representative of the colonization events observed and were taken from 4 to 17 days after root bacterization with fluorescently labelled derivatives. Scale bar represents 50 μm in all panels, except in ((<b>C</b>), 100 μm) and ((<b>F</b>), 20 μm). White arrows point to spots or microcolonies of the inoculated bacteria. co, cortical cells; vt, vascular tissue. In panels (<b>B</b>,<b>E</b>), the red channel was added to increase plant tissue contrast and improve visualization.</p> Full article ">Figure 6
<p>In vitro antagonistic activity of <span class="html-italic">Pseudomonas simiae</span> PICF7 and its mutants against <span class="html-italic">Verticillium dahliae</span> V937I. Pictures were taken 10 days after incubation at 25 °C. V937I, <span class="html-italic">Verticillium dahliae</span> V937I; PICF7, <span class="html-italic">Pseudomonas simiae</span> PICF7; PDA, Potato Dextrose Agar; and NA, Nutrient Agar. Images are representative plates used in two independent experiments (see <a href="#plants-10-00412-t002" class="html-table">Table 2</a>).</p> Full article ">
14 pages, 1669 KiB  
Article
Are Methanol-Derived Foliar Methyl Acetate Emissions a Tracer of Acetate-Mediated Drought Survival in Plants?
by Rebecca A. Dewhirst, Joseph Lei, Cassandra A. Afseth, Cristina Castanha, Christina M. Wistrom, Jenny C. Mortimer and Kolby J. Jardine
Plants 2021, 10(2), 411; https://doi.org/10.3390/plants10020411 - 23 Feb 2021
Cited by 3 | Viewed by 3410
Abstract
Upregulation of acetate fermentation in plants has recently been described as an evolutionarily conserved drought survival strategy, with the amount of acetate produced directly correlating to survival. However, destructive measurements are required to evaluate acetate-linked drought responses, limiting the temporal and spatial scales [...] Read more.
Upregulation of acetate fermentation in plants has recently been described as an evolutionarily conserved drought survival strategy, with the amount of acetate produced directly correlating to survival. However, destructive measurements are required to evaluate acetate-linked drought responses, limiting the temporal and spatial scales that can be studied. Here, 13C-labeling studies with poplar (Populus trichocarpa) branches confirmed that methyl acetate is produced in plants from the acetate-linked acetylation of methanol. Methyl acetate emissions from detached leaves were strongly stimulated during desiccation, with total emissions decreasing with the leaf developmental stage. In addition, diurnal methyl acetate emissions from whole physiologically active poplar branches increased as a function of temperature, and light-dark transitions resulted in significant emission bursts lasting several hours. During experimental drought treatments of potted poplar saplings, light-dark methyl acetate emission bursts were eliminated while strong enhancements in methyl acetate emissions lasting > 6 days were observed with their initiation coinciding with the suppression of transpiration and photosynthesis. The results suggest that methyl acetate emissions represent a novel non-invasive tracer of acetate-mediated temperature and drought survival response in plants. The findings may have important implications for the future understanding of acetate-mediated drought responses to transcription, cellular metabolism, and hormone signaling, as well as its associated changes in carbon cycling and water use from individual plants to whole ecosystems. Full article
(This article belongs to the Special Issue Water Stress and Desiccation Tolerance in Plants)
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<p>Schematic of acetate fermentation pathway and methyl acetate production. The addition of <sup>13</sup>C methanol and <sup>13</sup>C<sub>2</sub> acetate during these experiments are indicated in the orange box. Labeled <sup>13</sup>C atoms of the exogenous <sup>13</sup>C methanol and acetate are shown in orange. The four isotopologues (<sup>13</sup>C<sub>0–3</sub>) of methyl acetate formed are shown.</p> Full article ">Figure 2
<p>Real-time branch emissions in the light of methyl acetate isotopologues (nmol m<sup>−2</sup> s<sup>−1</sup>) with 0–3 <sup>13</sup>C-atoms and their stable carbon isotope ratios (<sup>13</sup>C<sub>1–3</sub>/<sup>13</sup>C<sub>0</sub>, %) during the delivery of a 10 mM [<sup>13</sup>C]methanol and [<sup>13</sup>C<sub>2</sub>]acetate solution to a detached poplar branch via the transpiration stream. (<b>a</b>) Emissions of methyl acetate isotopologues monitored using proton transfer reaction-mass spectrometry (PTR-MS) over the 12-h labeling period (10 min averages). Emissions of four isotopologues of methyl acetate were analyzed including unlabeled (<sup>13</sup>C<sub>0</sub>), singly labeled (<sup>13</sup>C<sub>1</sub>), doubly labeled (<sup>13</sup>C<sub>2</sub>), and triply labeled (<sup>13</sup>C<sub>3</sub>). (<b>b</b>) The <sup>13</sup>C<sub>1–3</sub>/<sup>13</sup>C<sub>0</sub> methyl acetate carbon isotope ratios (%) calculated from the real-time emission data shown in part a.</p> Full article ">Figure 3
<p>Methyl acetate emissions from detached poplar leaves during desiccation. (<b>a</b>) Methyl acetate emissions quantified over time following the introduction of the detached poplar leaves (2) inside the illuminated glass chamber with dry hydrocarbon-free air flowing through. Note the time when the detached leaves were introduced into the chamber is depicted on the plot with an arrow. (<b>b</b>) Summary of total methyl acetate emitted from detached poplar leaves for young (n = 9), mature (n = 7), and old (n = 6) leaf age classes.</p> Full article ">Figure 4
<p>Diurnal patterns of methyl acetate emissions from poplar under increasing temperatures. Methyl acetate emissions were monitored over a 24-h period from a physiologically active branch on a potted poplar tree within a temperature-controlled growth chamber with a constant light intensity during the day, but a diurnal increase in air temperature. (<b>a</b>) Time series of headspace CO<sub>2</sub> and H<sub>2</sub>O concentrations inside the dynamic branch enclosure together with methyl acetate emissions and air temperature. The greyed areas represent the night period when the growth chamber light was off. (<b>b</b>) Branch emissions of methyl acetate plotted versus air temperature.</p> Full article ">Figure 5
<p>Methyl acetate emissions during drought. Branch methyl acetate emissions together with headspace concentrations of CO<sub>2</sub> and H<sub>2</sub>O monitored continuously over 10 days with soil water additions withheld for the entire experiment. The greyed areas represent the night period where the LED-grow light was off.</p> Full article ">
12 pages, 664 KiB  
Review
Elevated CO2 and Reactive Oxygen Species in Stomatal Closure
by Xiaonan Ma and Ling Bai
Plants 2021, 10(2), 410; https://doi.org/10.3390/plants10020410 - 23 Feb 2021
Cited by 16 | Viewed by 5754
Abstract
Plant guard cell is essential for photosynthesis and transpiration. The aperture of stomata is sensitive to various environment factors. Carbon dioxide (CO2) is an important regulator of stomatal movement, and its signaling includes the perception, transduction and gene expression. The intersections [...] Read more.
Plant guard cell is essential for photosynthesis and transpiration. The aperture of stomata is sensitive to various environment factors. Carbon dioxide (CO2) is an important regulator of stomatal movement, and its signaling includes the perception, transduction and gene expression. The intersections with many other signal transduction pathways make the regulation of CO2 more complex. High levels of CO2 trigger stomata closure, and reactive oxygen species (ROS) as the key component has been demonstrated function in this regulation. Additional research is required to understand the underlying molecular mechanisms, especially for the detailed signal factors related with ROS in this response. This review focuses on Arabidopsis stomatal closure induced by high-level CO2, and summarizes current knowledge of the role of ROS involved in this process. Full article
(This article belongs to the Special Issue Specificity of ROS and Redox Regulatory Systems)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Schematic model of CO<sub>2</sub>-induced stomatal closure.</p> Full article ">
12 pages, 1423 KiB  
Perspective
Contributions of Reduced Susceptibility Alleles in Breeding Apple Cultivars with Durable Resistance to Fire Blight
by Sarah A. Kostick, Soon Li Teh and Kate M. Evans
Plants 2021, 10(2), 409; https://doi.org/10.3390/plants10020409 - 22 Feb 2021
Cited by 7 | Viewed by 3329
Abstract
Breeding apple cultivars with durable genetic resistance is a potential long-term solution to fire blight, a devastating bacterial disease caused by Erwinia amylovora. However, phenotyping resistance/susceptibility to fire blight is challenging due to E. amylovora strain virulence, differential host × strain interactions, [...] Read more.
Breeding apple cultivars with durable genetic resistance is a potential long-term solution to fire blight, a devastating bacterial disease caused by Erwinia amylovora. However, phenotyping resistance/susceptibility to fire blight is challenging due to E. amylovora strain virulence, differential host × strain interactions, quantitative host resistance, environmental influences on disease, and impacts of tree vigor on susceptibility. Inheritance of resistance/susceptibility to fire blight is complex and phenotypic information alone is insufficient to guide breeding decisions targeting resistance. Several quantitative trait loci (QTLs) associated with resistance/susceptibility to fire blight have been detected throughout the apple genome. Most resistance alleles at fire blight QTLs have been identified in wild Malus germplasm with poor fruit quality, which limits their breeding utility. Several QTLs have been identified in populations derived from cultivars and reduced-susceptibility alleles have been characterized in multiple important breeding parents. Although resistance to fire blight is an attractive target for DNA-informed breeding, relatively few trait-predictive DNA tests for breeding relevant fire blight QTLs are available. Here we discuss (1) considerations and challenges associated with phenotyping resistance/susceptibility to fire blight; (2) sources of resistance that have been identified for use as parents; and (3) our perspective on short and long-term strategies to breed apple cultivars with durable resistance to fire blight with emphasis on the potential contributions of reduced susceptibility alleles to achieve this goal. Full article
(This article belongs to the Special Issue Plant Genetic Resources and Breeding of Clonally Propagated Crops)
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<p><span class="html-italic">Erwinia amylovora</span> can infect the flowers (<b>A</b>), fruits (<b>B</b>), and vegetative tissue (<b>C</b>–<b>H</b>) of apple, which can result in bacterial ooze (<b>B</b>–<b>D</b>) and necrosis (<b>A</b>–<b>H</b>). A necrotic shepherd’s crook (<b>C</b>) is characteristic of a highly susceptible response to invasion of host shoot tissues by <span class="html-italic">E. amylovora</span>. Fire blight symptom severity varies among <span class="html-italic">Malus</span> cultivars and species. Susceptible responses that are depicted were the result of natural infection of flowers and fruit (<b>A</b>,<b>B</b>) under field conditions or artificial inoculation of shoots with <span class="html-italic">Ea</span> 153n under field (<b>C</b>–<b>G</b>) or greenhouse (<b>H</b>) conditions.</p> Full article ">Figure 2
<p>Short- and long-term strategies for breeding apple cultivars with durable resistance to fire blight. In the short-term, published phenotypic and genetic information could guide parental selection and phenotypic seedling selection could be used to cull highly susceptible individuals. DNA-informed breeding for resistance to fire blight is a long-term breeding strategy.</p> Full article ">
48 pages, 22650 KiB  
Article
Integrative Taxonomy and Molecular Phylogeny of the Plant-Parasitic Nematode Genus Paratylenchus (Nematoda: Paratylenchinae): Linking Species with Molecular Barcodes
by Phougeishangbam Rolish Singh, Gerrit Karssen, Marjolein Couvreur, Sergei A. Subbotin and Wim Bert
Plants 2021, 10(2), 408; https://doi.org/10.3390/plants10020408 - 22 Feb 2021
Cited by 26 | Viewed by 6934
Abstract
Pin nematodes of the genus Paratylenchus are obligate ectoparasites of a wide variety of plants that are distributed worldwide. In this study, individual morphologically vouchered nematode specimens of fourteen Paratylenchus species, including P. aculentus, P. elachistus, P. goodeyi, P. holdemani, P. idalimus, P. [...] Read more.
Pin nematodes of the genus Paratylenchus are obligate ectoparasites of a wide variety of plants that are distributed worldwide. In this study, individual morphologically vouchered nematode specimens of fourteen Paratylenchus species, including P. aculentus, P. elachistus, P. goodeyi, P. holdemani, P. idalimus, P. microdorus, P. nanus, P. neoamblycephalus, P. straeleni and P. veruculatus, are unequivocally linked to the D2-D3 of 28S, ITS, 18S rRNA and COI gene sequences. Combined with scanning electron microscopy and a molecular analysis of an additional nine known and thirteen unknown species originating from diverse geographic regions, a total of 92 D2-D3 of 28S, 41 ITS, 57 18S rRNA and 111 COI new gene sequences are presented. Paratylenchus elachistus, P. holdemani and P. neoamblycephalus are recorded for the first time in Belgium and P. idalimus for the first time in Europe. Paratylenchus is an excellent example of an incredibly diverse yet morphologically minimalistic plant-parasitic genus, and this study provides an integrated analysis of all available data, including coalescence-based molecular species delimitation, resulting in an updated Paratylenchus phylogeny and the corrective reassignment of 18 D2-D3 of 28S, 3 ITS, 3 18S rRNA and 25 COI gene sequences that were previously unidentified or incorrectly classified. Full article
(This article belongs to the Special Issue The Systematics, Morphological, and Molecular Characterization of Economically Important Plant–Parasitic Nematodes: A Themed Issue in Honor of Dr. Gary Bauchan)
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<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus aculentus</span> females: (<b>A</b>) face view; (<b>B</b>,<b>D,E</b>) anterior region; (<b>C,J</b>) total body; (<b>G</b>) vulva region; (<b>F</b>,<b>H</b>,<b>I</b>) tail region.</p> Full article ">Figure 2
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus elachistus</span> females: (<b>A</b>,<b>B</b>) face view; (<b>C</b>,<b>D</b>,<b>G</b>–<b>I</b>) anterior region; (<b>E</b>,<b>F</b>) vulva region; (<b>J</b>) total body; (<b>K</b>–<b>Q</b>) tail region; arrows pointed to deirid in (<b>J</b>) and spermatheca in (<b>M</b>).</p> Full article ">Figure 3
<p>Light microscopy images of <span class="html-italic">Paratylenchus goodeyi</span> females: (<b>A</b>,<b>B</b>) total body; (<b>C</b>–<b>G</b>) anterior region; (<b>H</b>,<b>I</b>) lateral field; (<b>J</b>–<b>L</b>) tail region; arrows pointed to spermatheca in A, protruding submedian lobe in G and post-vulva sac in K.</p> Full article ">Figure 4
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus holdemani</span> females: (<b>A</b>,<b>F</b>) face view; (<b>B</b>–<b>D</b>,<b>G</b>,<b>H</b>) anterior region; (<b>E</b>,<b>I</b>) total body; (<b>J</b>–<b>O</b>) tail region; arrow pointed to deirid in (<b>E</b>).</p> Full article ">Figure 5
<p>Light microscopy images of <span class="html-italic">Paratylenchus idalimus</span> females from sample BE19: (<b>A</b>) total body; (<b>B</b>–<b>D</b>) anterior region; (<b>E</b>–<b>G</b>) lateral field and tail region; arrow pointed to secretory–excretory pore in D.</p> Full article ">Figure 6
<p>Light microscopy images of <span class="html-italic">Paratylenchus idalimus</span> females from sample BE20: (<b>A</b>,<b>F</b>) total body; (<b>B</b>–<b>E</b>) anterior region; (<b>G</b>–<b>J</b>) tail region.</p> Full article ">Figure 7
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus microdorus</span> females: (<b>A</b>) face view; (<b>B</b>) total body; (<b>C</b>–<b>F</b>) anterior region; (<b>G</b>–<b>J</b>) tail region.</p> Full article ">Figure 8
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus nanus</span> females: (<b>A</b>,<b>E</b>,<b>F</b>,<b>L</b>) face view; (<b>B</b>–<b>D</b>,<b>G</b>,<b>H</b>,<b>J</b>,<b>K</b>,<b>M</b>) anterior region; (<b>I</b>) total body; (<b>N</b>,<b>O</b>,<b>P</b>–<b>U</b>) tail region.</p> Full article ">Figure 9
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus neoamblycephalus</span> females: (<b>A</b>,<b>C</b>) face view; (<b>B</b>) total body; (<b>D</b>–<b>H</b>) anterior region; (<b>I</b>–<b>O</b>) tail region; arrows pointed to secretory–excretory pore in (<b>H</b>) and deirid in (<b>G</b>).</p> Full article ">Figure 10
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus straeleni</span> females: (<b>A</b>) whole body; (<b>B</b>,<b>D</b>) face view; (<b>C</b>,<b>G</b>–<b>J</b>) anterior region; (<b>E</b>) vulva region; (<b>F</b>,<b>K</b>,<b>L</b>) tail region; (<b>M</b>) total body; arrows pointed to deirids in (<b>A</b>,<b>C</b>).</p> Full article ">Figure 11
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus veruculatus</span> females: (<b>A</b>–<b>C</b>) face view; (<b>D</b>–<b>G</b>) anterior region; (<b>H</b>,<b>O</b>) total body; (<b>I</b>–<b>N</b>) lateral field and tail region.</p> Full article ">Figure 12
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus</span> sp.2 females: (<b>A</b>,<b>B</b>) face view; (<b>C</b>) total body; (<b>D</b>–<b>I</b>) anterior region; (<b>J</b>–<b>O</b>) tail region; arrows pointed at deirids in (<b>C</b>,<b>I</b>).</p> Full article ">Figure 13
<p>Light microscopy images of <span class="html-italic">Paratylenchus</span> sp.BE11 females: (<b>A</b>) total body; (<b>B</b>–<b>E</b>) anterior region; (<b>F</b>–<b>H</b>) tail region; (<b>I</b>) total body; (<b>J</b>) lateral field.</p> Full article ">Figure 14
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus</span> sp.D females; (<b>A</b>,<b>G</b>,<b>H</b>) face view; (<b>B</b>–<b>F</b>,<b>M</b>,<b>N</b>) anterior region; (<b>I</b>,<b>L</b>) total body; (<b>J</b>,<b>K</b>,<b>O</b>–<b>Q</b>) tail region; arrow pointed to deirid in L.</p> Full article ">Figure 15
<p>Light and scanning electron microscopy images of <span class="html-italic">Paratylenchus</span> sp.F females: (<b>A</b>–<b>C</b>) face view; (<b>D</b>,<b>E</b>,<b>L</b>,<b>M</b>,<b>P</b>,<b>Q</b>) anterior region; (<b>F</b>,<b>G</b>) vulva region; (<b>H</b>–<b>K</b>,<b>O</b>,<b>R</b>–<b>T</b>) tail region; (<b>N</b>) total body.</p> Full article ">Figure 16
<p>Phylogenetic relationships within populations and species of <span class="html-italic">Paratylenchus</span>, as inferred from Bayesian analysis using the D2-D3 of 28S rRNA gene sequence dataset with the GTR + I + G model. Posterior probability of more than 70% is given for the appropriate clades. Newly obtained sequences are indicated in bold. <sup>1</sup> = originally identified as <span class="html-italic">P. nanus</span>, <sup>2</sup> = originally identified as <span class="html-italic">P. bukowinensis</span>, <sup>3</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp., <sup>4</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp.8, <sup>5</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp.E, <sup>6</sup> = originally identified as <span class="html-italic">Gracilacus</span> sp. <sup>7</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp.5 and <sup>8</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp.6. Black and grey bars represent species boundaries estimated by generalized mixed-yule coalescent (GMYC) and Poisson tree process (bPTP) methods, respectively (only differences with GMYC provided).</p> Full article ">Figure 17
<p>Phylogenetic relationships within populations and species of <span class="html-italic">Paratylenchus</span> as inferred from Bayesian analysis using the ITS rRNA gene sequence dataset with the GTR + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold. <sup>1</sup> = originally identified as <span class="html-italic">P. nanus</span> and <sup>2</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp. Black and grey bars represent species boundaries estimated by GMYC and bPTP methods, respectively.</p> Full article ">Figure 18
<p>Phylogenetic relationships within populations and species of <span class="html-italic">Paratylenchus</span>, as inferred from Bayesian analysis using the 18S rRNA gene sequence dataset with the GTR + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold. <sup>1</sup> = originally identified as <span class="html-italic">P. dianthus</span> and <sup>2</sup> = originally identified as <span class="html-italic">P. nanus</span>. Black and grey bars represent species boundaries estimated by GMYC and bPTP methods, respectively.</p> Full article ">Figure 19
<p>(<b>A</b>). Phylogenetic relationships within populations and species of <span class="html-italic">Paratylenchus</span>, as inferred from Bayesian analysis using the <span class="html-italic">COI</span> gene sequence dataset with the GTR + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold. <sup>1</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp., <sup>2</sup> = originally identified as <span class="html-italic">P. nanus</span>, <sup>3</sup> = identified as <span class="html-italic">Paratylenchus</span> sp.E, <sup>4</sup> = originally identified as <span class="html-italic">Gracilacus</span> sp., <sup>5</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp.8, <sup>6</sup> = originally identified as <span class="html-italic">Paratylenchus</span> sp.B; (<b>B</b>). Statistical parsimony network showing the phylogenetic relationships between <span class="html-italic">COI</span> haplotypes for <span class="html-italic">P. straeleni</span>; (<b>C</b>). Statistical parsimony network showing the phylogenetic relationships between <span class="html-italic">COI</span> haplotypes for <span class="html-italic">P</span>. <span class="html-italic">enigmaticus</span>. Pies (circles) represent the sequences with the same haplotype and their size is proportional to the number of these sequences in the samples. Numbers of nucleotide differences between the sequences are indicated on lines connecting the pies. Small black circles represent missing haplotypes. Bars represent species boundaries estimated by both GMYC and bPTP methods (identical results).</p> Full article ">
13 pages, 2637 KiB  
Article
A Long Journey of CICA-17 Quinoa Variety to Salinity Conditions in Egypt: Mineral Concentration in the Seeds
by Juan A. González, Leonardo Hinojosa, María I. Mercado, José-Luis Fernández-Turiel, Didier Bazile, Graciela I. Ponessa, Sayed Eisa, Daniela A. González, Marta Rejas, Sayed Hussin, Emad H. Abd El-Samad, Ahmed Abdel-Ati and Mohamed E. A. Ebrahim
Plants 2021, 10(2), 407; https://doi.org/10.3390/plants10020407 - 22 Feb 2021
Cited by 15 | Viewed by 3884
Abstract
Quinoa may be a promising alternative solution for arid regions, and it is necessary to test yield and mineral accumulation in grains under different soil types. Field experiments with Chenopodium quinoa (cv. CICA-17) were performed in Egypt in non-saline (electrical conductivity, 1.9 dS [...] Read more.
Quinoa may be a promising alternative solution for arid regions, and it is necessary to test yield and mineral accumulation in grains under different soil types. Field experiments with Chenopodium quinoa (cv. CICA-17) were performed in Egypt in non-saline (electrical conductivity, 1.9 dS m−1) and saline (20 dS m−1) soils. Thirty-four chemical elements were studied in these crops. Results show different yields and mineral accumulations in the grains. Potassium (K), P, Mg, Ca, Na, Mn, and Fe are the main elements occurring in the quinoa grains, but their concentrations change between both soil types. Besides, soil salinity induced changes in the mineral pattern distribution among the different grain organs. Sodium was detected in the pericarp but not in other tissues. Pericarp structure may be a shield to prevent sodium entry to the underlying tissues but not for chloride, increasing its content in saline conditions. Under saline conditions, yield decreased to near 47%, and grain sizes greater than 1.68 mm were unfavored. Quinoa may serve as a complementary crop in the marginal lands of Egypt. It has an excellent nutrition perspective due to its mineral content and has a high potential to adapt to semi-arid and arid environments. Full article
(This article belongs to the Special Issue Worldwide Evaluations of Quinoa—Biodiversity and Food Security under Climate Change Pressures)
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<p>Effect of non-saline and saline soils on grain yield (mean ± SE) on <span class="html-italic">C. quinoa</span> cv. CICA-17. Different letters above columns indicate significant differences between means at <span class="html-italic">p</span> &lt; 0.05, according to the <span class="html-italic">t</span>-test.</p> Full article ">Figure 2
<p>Effects of non-saline and saline soils on the weight (mean ± SE) of 1000-seeds of <span class="html-italic">C. quinoa</span> cv. CICA-17 plants. Significant differences between means (<span class="html-italic">p</span> ≤ 0.05) are indicated by different letters above columns according to the <span class="html-italic">t</span>-test.</p> Full article ">Figure 3
<p>Seeds diameter distribution of <span class="html-italic">C. quinoa</span> cv. CICA-17 obtained in non-saline and saline soils. All the differences were significant (<span class="html-italic">p</span> ≤ 0.05) according to the <span class="html-italic">t</span>-test. A: &lt;1.41 – &gt;1.0 mm; B: &lt;1.68 – &gt;1.41 mm; C: &lt;2.00 – &gt;1.68 mm; D: ≥2 mm.</p> Full article ">Figure 4
<p>SEM photographs of <span class="html-italic">C. quinoa</span> cv. CICA-17. (<b>A</b>) grain external view; (<b>B</b>) seed with manually removed epicarp; and (<b>C</b>) longitudinal medial grain section. Pe, pericarp; Pe r, pericarp partially removed; Ep, episperm; En, endosperm; P, perisperm; Emb, embryo with a radicle-hypocotyl axis (r) and cotyledon (co).</p> Full article ">Figure 5
<p>Spatial distribution of elements analyzed by SEM-EDX in grain longitudinal medial sections of <span class="html-italic">C. quinoa</span> cv. CICA-17, cultivated under non-saline (<b>A</b>–<b>K</b>) and saline (<b>L</b>–<b>V</b>) conditions. Ep, episperm; En, endosperm; P, perisperm; Pe, pericarp; Emb, embryo with the radicle-hypocotyl axis (r) and cotyledon (co). Arrowhead indicates the greater abundance of the mapped element.</p> Full article ">
21 pages, 1282 KiB  
Review
A Review and Secondary Analysis of Competition-Related Impacts of Nonindigenous Aquatic Plants in the Laurentian Great Lakes
by Rochelle Sturtevant, El Lower, Austin Bartos and Ashley Elgin
Plants 2021, 10(2), 406; https://doi.org/10.3390/plants10020406 - 20 Feb 2021
Cited by 1 | Viewed by 4468
Abstract
The Laurentian Great Lakes of North America are home to thousands of native fishes, invertebrates, plants, and other species that not only provide recreational and economic value to the region but also hold an important ecological value. However, there are also 55 nonindigenous [...] Read more.
The Laurentian Great Lakes of North America are home to thousands of native fishes, invertebrates, plants, and other species that not only provide recreational and economic value to the region but also hold an important ecological value. However, there are also 55 nonindigenous species of aquatic plants that may be competing with native species and affecting this value. Here, we use a key regional database—the Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS)—to describe the introduction of nonindigenous aquatic plants in the Great Lakes region and to examine patterns relating to their capacity to compete with native plants species. Specifically, we used an existing catalog of environmental impact assessments to qualitatively evaluate the potential for each nonindigenous plant species to outcompete native plant species for available resources. Despite an invasion record spanning nearly two centuries (1837–2020), a great deal remains unknown about the impact of competition by these species. Nonetheless, our synthesis of existing documentation reveals that many of these nonindigenous species have notable impacts on the native plant communities of the region in general and on species of concern in particular. Furthermore, we provide a thorough summary of the diverse adaptations that may contribute to giving these nonindigenous plants a competitive advantage. Adaptations that have been previously found to aid successful invasions were common in 98% of the nonindigenous aquatic plant species in the database. Full article
(This article belongs to the Special Issue Competition among Native and Invasive Plants)
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<p>Cumulative introduction of nonindigenous plants to the Great Lakes basin by vector of introduction. Note the Hybrid vector represents recombination of a nonindigenous captive species introduced intentionally as a garden plant with a native plant, probably via cross-pollination.</p> Full article ">Figure 2
<p>Distribution of aquatic nonindigenous plants in the Great Lakes basin by sub-watershed.</p> Full article ">Figure 3
<p>Nonindigenous aquatic plants by impact category—limited to impact attributed to competition with native plant species (n = 55). (Re-analysis of the impact assessments which appear in [<a href="#B29-plants-10-00406" class="html-bibr">29</a>,<a href="#B30-plants-10-00406" class="html-bibr">30</a>,<a href="#B31-plants-10-00406" class="html-bibr">31</a>,<a href="#B32-plants-10-00406" class="html-bibr">32</a>,<a href="#B33-plants-10-00406" class="html-bibr">33</a>,<a href="#B34-plants-10-00406" class="html-bibr">34</a>,<a href="#B35-plants-10-00406" class="html-bibr">35</a>,<a href="#B36-plants-10-00406" class="html-bibr">36</a>,<a href="#B37-plants-10-00406" class="html-bibr">37</a>,<a href="#B38-plants-10-00406" class="html-bibr">38</a>,<a href="#B39-plants-10-00406" class="html-bibr">39</a>,<a href="#B40-plants-10-00406" class="html-bibr">40</a>,<a href="#B41-plants-10-00406" class="html-bibr">41</a>,<a href="#B42-plants-10-00406" class="html-bibr">42</a>,<a href="#B43-plants-10-00406" class="html-bibr">43</a>,<a href="#B44-plants-10-00406" class="html-bibr">44</a>].</p> Full article ">Figure 4
<p>Adaptations identified as assisting in competition (n = 55; however, species can have multiple adaptations). Species scoring “unknown” or “low impact” typically also have adaptations noted and are included in this analysis.</p> Full article ">
22 pages, 571 KiB  
Review
Assessment of Glyphosate Impact on the Agrofood Ecosystem
by Yaxin Sang, Juan-Carlos Mejuto, Jianbo Xiao and Jesus Simal-Gandara
Plants 2021, 10(2), 405; https://doi.org/10.3390/plants10020405 - 20 Feb 2021
Cited by 14 | Viewed by 6096
Abstract
Agro-industries should adopt effective strategies to use agrochemicals such as glyphosate herbicides cautiously in order to protect public health. This entails careful testing and risk assessment of available choices, and also educating farmers and users with mitigation strategies in ecosystem protection and sustainable [...] Read more.
Agro-industries should adopt effective strategies to use agrochemicals such as glyphosate herbicides cautiously in order to protect public health. This entails careful testing and risk assessment of available choices, and also educating farmers and users with mitigation strategies in ecosystem protection and sustainable development. The key to success in this endeavour is using scientific research on biological pest control, organic farming and regulatory control, etc., for new developments in food production and safety, and for environmental protection. Education and research is of paramount importance for food and nutrition security in the shadow of climate change, and their consequences in food production and consumption safety and sustainability. This review, therefore, diagnoses on the use of glyphosate and the associated development of glyphosate-resistant weeds. It also deals with the risk assessment on human health of glyphosate formulations through environment and dietary exposures based on the impact of glyphosate and its metabolite AMPA—(aminomethyl)phosphonic acid—on water and food. All this to setup further conclusions and recommendations on the regulated use of glyphosate and how to mitigate the adverse effects. Full article
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Structural formula of glyphosate (<b>a</b>) and AMPA –(aminomethyl)phosphonic acid– (<b>b</b>), together with degradation pathway for glyphosate in soil (<b>c</b>).</p> Full article ">
25 pages, 2125 KiB  
Article
How to Protect Natural Habitats of Rare Terrestrial Orchids Effectively: A Comparative Case Study of Cypripedium calceolus in Different Geographical Regions of Europe
by Anna Jakubska-Busse, Spyros Tsiftsis, Michał Śliwiński, Zdenka Křenová, Vladan Djordjević, Corina Steiu, Marta Kolanowska, Petr Efimov, Sebastian Hennigs, Pavel Lustyk and Karel (C.A.J.) Kreutz
Plants 2021, 10(2), 404; https://doi.org/10.3390/plants10020404 - 20 Feb 2021
Cited by 16 | Viewed by 5449
Abstract
In this article we present and discuss the main factors that threaten natural populations of Cypripedium calceolus (lady’s slipper orchid) in Europe, and we propose conservation strategies and directions for protective actions of its population on a regional scale. European C. calceolus populations [...] Read more.
In this article we present and discuss the main factors that threaten natural populations of Cypripedium calceolus (lady’s slipper orchid) in Europe, and we propose conservation strategies and directions for protective actions of its population on a regional scale. European C. calceolus populations have decreased significantly in the last two decades, in both number and size. A key result of the present study is an evaluation of the effectiveness of the Natura 2000 network across the European Union (EU) countries. Northern and/or mountainous countries present higher percentages of potentially suitable areas within the Natura 2000 network. Finland and the United Kingdom are the exceptions to this rule. It is predicted that, due to global warming, the coverage of niches suitable for C. calceolus will decrease in countries in which now-healthy colonies exist. However, as plant species can occur in micro-sites with suitable environmental conditions (e.g., microclimate, vegetation, soil factors) which cannot be predicted as suitable at coarser spatial resolutions, conservation efforts should be focused on management of local healthy populations. For the effective protection of C. calceolus in Natura 2000 sites, the participation of experts in botany, including orchid biology, is necessary at several stages. Full article
(This article belongs to the Special Issue Orchid Distribution, Evolutionary Ecology, and Population Dynamics)
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<p>Map of Europe presenting the IUCN threat category of <span class="html-italic">Cypripedium calceolus</span> in each country. The map was created using the projected coordinate system “Lambert_Azimuthal_Equal_Area”.</p> Full article ">Figure 2
<p>Results of hierarchical cluster analysis (unweighted pair group method with arithmetic mean, UPGMA) showing the degree of similarity of European countries where <span class="html-italic">Cypripedium calceolus</span> is present, using Bray-Curtis distances of the factors that have been identified as threats at each country. The vertical red line denotes the limit that led to the identification of the five groups of countries.</p> Full article ">Figure 3
<p>Groups of countries in which <span class="html-italic">Cypripedium calceolus</span> faces similar threats. The groups of countries have been identified on the basis of an unweighted pair-group method with arithmetic mean (UPGMA) cluster algorithm. The map was created using the projected coordinate system “Lambert_Azimuthal_Equal_Area”.</p> Full article ">Figure 4
<p>Proposed protective-action directions of <span class="html-italic">Cypripedium calceolus</span> populations on a regional scale.</p> Full article ">
16 pages, 2274 KiB  
Article
Enhancement of Brassica napus Tolerance to High Saline Conditions by Seed Priming
by Panaiotis M. Stassinos, Massimiliano Rossi, Ilaria Borromeo, Concetta Capo, Simone Beninati and Cinzia Forni
Plants 2021, 10(2), 403; https://doi.org/10.3390/plants10020403 - 20 Feb 2021
Cited by 20 | Viewed by 3346
Abstract
Plants grown in saline soils undergo osmotic and oxidative stresses, affecting growth and photosynthesis and, consequently, the yield. Therefore, the increase in soil salinity is a major threat to crop productivity worldwide. Plant’s tolerance can be ameliorated by applying simple methods that induce [...] Read more.
Plants grown in saline soils undergo osmotic and oxidative stresses, affecting growth and photosynthesis and, consequently, the yield. Therefore, the increase in soil salinity is a major threat to crop productivity worldwide. Plant’s tolerance can be ameliorated by applying simple methods that induce them to adopt morphological and physiological adjustments to counteract stress. In this work, we evaluated the effects of seed priming on salt stress response in three cultivars of rapeseed (Brassica napus L.) that had different tolerance levels. Seed chemical priming was performed with 2.5 mM spermine (SPM), 5 mM spermidine (SPD), 40 mM NaCl and 2.5 mM Ca (NO3)2. Primed and not primed seeds were sown on saline and not saline (controls) media, and morphological and physiological parameters were determined. Since SPD treatment was effective in reducing salinity negative effects on growth, membrane integrity and photosynthetic pigments, we selected this priming to further investigate plant salt stress response. The positive effects of this seed treatment on growth and physiological responses were evident when primed plants were compared to not primed ones, grown under the same saline conditions. SPD priming ameliorated the tolerance towards saline stress, in a genotype-independent manner, by increasing photosynthetic pigments, proline amounts and antioxidant responses in all cultivars exposed to salt. These results may open new perspectives for crop productivity in the struggle against soil salinization. Full article
(This article belongs to the Special Issue Abiotic Stress Tolerance in Crop and Medical Plants)
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<p>Effect of spermidine priming on total phenol content of rapeseed cultivars exposed to saline conditions. Data are expressed as means ± SE (<span class="html-italic">n</span> = 3). Mean values in the column marked by different letters are significantly different within the same group (<span class="html-italic">p</span> ≤ 0.05; ANOVA and Tukey–Kramer test). Significant differences between groups are reported as * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001.</p> Full article ">Figure 2
<p>Effect of spermidine priming on PAL activity of rapeseed cultivars exposed to saline conditions. Data are expressed as means ± SE (<span class="html-italic">n</span> = 3). Mean values in the column marked by different letters are significantly different within the same group (<span class="html-italic">p</span> ≤ 0.05; ANOVA and Tukey–Kramer test). Significant differences between groups are reported as * <span class="html-italic">p</span> &lt; 0.05; *** <span class="html-italic">p</span> &lt; 0.001.</p> Full article ">Figure 3
<p>Effect of spermidine priming on SOD activity of rapeseed cultivars exposed to saline conditions ((<b>a</b>): Sy Saveo, (<b>b</b>): Edimax, (<b>c</b>): Dynastie).</p> Full article ">Figure 4
<p>Effect of spermidine priming on proline amount of rapeseed cultivars exposed to saline conditions. Data are expressed as means ± SE (<span class="html-italic">n</span> = 3). Mean values in the column marked by different letters are significantly different within the same group (<span class="html-italic">p</span> ≤ 0.05; ANOVA and Tukey–Kramer test). Significant differences between groups are reported as * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001.</p> Full article ">Figure 5
<p>Rapeseed seedlings of the cultivars (Controls below; exposed to 80 mM NaCl above).</p> Full article ">
19 pages, 3659 KiB  
Article
Flavan-3-ols and Proanthocyanidins in Japanese, Bohemian and Giant Knotweed
by Maja Bensa, Vesna Glavnik and Irena Vovk
Plants 2021, 10(2), 402; https://doi.org/10.3390/plants10020402 - 20 Feb 2021
Cited by 9 | Viewed by 2828
Abstract
Flavan-3-ols and proanthocyanidins of invasive alien plants Japanese knotweed (Fallopia japonica Houtt.), giant knotweed (Fallopia sachalinensis F. Schmidt) and Bohemian knotweed (Fallopia × bohemica (Chrtek & Chrtkova) J.P. Bailey) were investigated using high performance thin-layer chromatography (HPTLC) coupled [...] Read more.
Flavan-3-ols and proanthocyanidins of invasive alien plants Japanese knotweed (Fallopia japonica Houtt.), giant knotweed (Fallopia sachalinensis F. Schmidt) and Bohemian knotweed (Fallopia × bohemica (Chrtek & Chrtkova) J.P. Bailey) were investigated using high performance thin-layer chromatography (HPTLC) coupled to densitometry, image analysis and mass spectrometry (HPTLC–MS/MS). (+)-Catechin, (−)-epicatechin, (−)-epicatechin gallate and procyanidin B2 were found in rhizomes of these three species, and for the first time in Bohemian knotweed. (−)-Epicatechin gallate, procyanidin B1, procyanidin B2 and procyanidin C1 were found in giant knotweed rhizomes for the first time. Rhizomes of Bohemian and giant knotweed have the same chemical profiles of proanthocyanidins with respect to the degree of polymerization and with respect to gallates. Japanese and Bohemian knotweed have equal chromatographic fingerprint profiles with the additional peak not present in giant knotweed. Within the individual species giant knotweed rhizomes and leaves have the most similar fingerprints, while the fingerprints of Japanese and Bohemian knotweed rhizomes have additional peaks not found in leaves. Rhizomes of all three species proved to be a rich source of proanthocyanidins, with the highest content in Japanese and the lowest in Bohemian knotweed (based on the total peak areas). The contents of monomers in Japanese, Bohemian and giant knotweed rhizomes were 2.99 kg/t of dry mass (DM), 1.52 kg/t DM, 2.36 kg/t DM, respectively, while the contents of dimers were 2.81 kg/t DM, 1.09 kg/t DM, 2.17 kg/t DM, respectively. All B-type proanthocyanidins from monomers to decamers (monomers—flavan-3-ols, dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, nonamers and decamers) and some of their gallates (monomer gallates, dimer gallates, dimer digallates, trimer gallates, tetramer gallates, pentamer gallates and hexamer gallates) were identified in rhizomes of Bohemian knotweed and giant knotweed. Pentamer gallates, hexamers, hexamer gallates, nonamers and decamers were identified for the first time in this study in Bohemian and giant knotweed rhizomes. Full article
(This article belongs to the Collection Bioactive Compounds in Plants)
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<p>HPTLC chromatograms for the qualitative determination of flavan-3-ols and proanthocyanidins in STSs from rhizomes (2 μL, 50 mg/mL) of Japanese (track 6), Bohemian (track 7) and giant (track 8) knotweed based on standards. The HPTLC silica gel plate was developed with tol uene—acetone—formic acid (3:6:1, <span class="html-italic">v/v</span>) and documented at white light after derivatization with DMACA detection reagent. Applications of standards: (−)-gallocatechin gallate (0.2 µg; track 1), (−)-catechin gallate (0.2 µg; track 2), procyanidin C1 (0.3 µg; track 3), procyanidin B3 (0.2 µg; track 4), (−)-epicatechin (0.1 µg; track 5, higher R<sub>F</sub>), (−)-epigallocatechin (0.2 µg; track 5, lower R<sub>F</sub>), (+)-catechin (0.1 µg; track 9, higher R<sub>F</sub>) (−)-gallocatechin (0.2 µg; track 9, lower R<sub>F</sub>), (−)-epicatechin gallate (0.2 µg; track 10), procyanidin B1 (0.2 µg; track 11), procyanidin B2 (0.2 µg; track 12) (−)-epigallocatechin gallate (0.2 µg; track 13).</p> Full article ">Figure 2
<p>HPTLC chromatograms for the qualitative determination of flavan-3-ols and proanthocyanidins in STSs from rhizomes (1 μL, 50 mg/mL) of Japanese (track 6), Bohemian (track 7) and giant (track 8) knotweed based on standards. The HPTLC cellulose plates were developed with water (<b>A</b>), 1-propanol–water–acetic acid (4:2:1, <span class="html-italic">v/v</span>) (<b>B</b>), 1-propanol–water–acetic acid (20:80:1, <span class="html-italic">v/v</span>) (<b>C</b>), and documented at white light after derivatization with DMACA detection reagent. The ap plications of standards: (−)-gallocatechin gallate (60 ng; track 1), (−)-catechin gallate (60 ng; track 2), procyanidin C1 (150 ng; track 3), procyanidin B3 (100 ng; track 4), (−)-epicatechin (50 ng; track 5, higher R<sub>F</sub>), (−)-epigallocatechin (60 ng; track 5, lower R<sub>F</sub>), (+)-catechin (50 ng; track 9, higher R<sub>F</sub>), (−)-gallocatechin (60 ng; track 9, lower R<sub>F</sub>), (−)-epicatechin gallate (60 ng; track 10), procyanidin B1 (120 ng; track 11), procyanidin B2 (90 ng, track 12) (−)-epigallocatechin gallate (60 ng; track 13).</p> Full article ">Figure 3
<p>HPTLC chromatograms used for the quantitative determination of proanthocyanidins in STSs from rhizomes (1 μL, 50 mg/mL) of Japanese (tracks 2 and 8), Bohemian (tracks 4 and 10) and giant (tracks 6 and 12) knotweed and standard solutions of (−)-epicatechin and procyanidin B2. The HPTLC silica gel plate was developed with toluene–acetone–formic acid (3:6:1, <span class="html-italic">v/v</span>) and documented at white light after derivatization with DMACA detection reagent. The applications of (−)-epicatechin and procyanidin B2 standard solutions: track 1: 30 ng; track 3: 40 ng; track 5: 60 ng; track 7: 80 ng; track 9: 100 ng; track 11: 120 ng; track 13: 150 ng.</p> Full article ">Figure 4
<p>The densitograms of STSs (1 μL, 50 mg/mL) from rhizomes of Japanese (JK), giant (GK) and Bohemian (BK) knotweed and standard solutions (STD, 40 ng) of (−)-epicatechin (EC) and procyanidin B2 (B2) scanned in absorption/reflectance mode at 280 nm before the derivatization (<b>A</b>) and at 655 nm after the derivatization with DMACA reagent (<b>B</b>). The HPTLC silica gel plate was developed with toluene–acetone–formic acid (3:6:1, <span class="html-italic">v/v</span>).</p> Full article ">Figure 5
<p>Comparisons of the videodensitogram of standards (−)-epicatechin (EC; R<sub>F</sub> = 0.82) and procyanidin B2 (B2; R<sub>F</sub> = 0.63) (30 ng; dashed green line) with the videodensitograms of the fingerprint profiles of STSs (1 μL, 50 mg/mL) from rhizomes of Japanese (black line), Bohemian (blue line) and giant knotweed (red line). The videodensitograms were obtained in absorption mode by image analysis of the HPTLC silica gel plate after the development with toluene–acetone–formic acid (3:6:1, <span class="html-italic">v/v</span>) and after the derivatization with DMACA detection reagent. The asterisk (*) indicates the peaks that are specific to Japanese and Bohemian knotweed rhizomes.</p> Full article ">Figure 6
<p>Comparisons of the videodensitogram fingerprint profiles of STSs (1 μL, 50 mg/mL) from leaves and rhizomes of the same knotweed species (Japanese (<b>A</b>), Bohemian (<b>B</b>) and giant (<b>C</b>) knotweed) with the videodensitogram of standards (−)-epicatechin (EC; R<sub>F</sub> = 0.82) and procyanidin B2 (B2; R<sub>F</sub> = 0.63) (30 ng; dashed green line). The videodensitograms were obtained in absorption mode by image analysis of the HPTLC silica gel plates after the development with toluene–acetone–formic acid (3:6:1, <span class="html-italic">v/v</span>) and after the derivatization with DMACA detection reagent. The asterisks (*) in dicate peaks that are only present in the rhizomes of Japanese and Bohemian knotweed.</p> Full article ">Figure 7
<p>Comparison of the means of the total peak areas of proanthocyanidins (blue bands in chromatograms) for STSs from rhizomes of Japanese (JK), Bohemian (BK), and giant (GK) knotweed. The mean of the total peak areas was calculated from the total peak areas of the videodensitograms of two equal applications of the same STS on the HPTLC silica gel plate (<a href="#plants-10-00402-f003" class="html-fig">Figure 3</a>) after the development with toluene–acetone–formic acid (3:6:1, <span class="html-italic">v/v</span>) and after the derivatization with DMACA detection reagent.</p> Full article ">Figure 8
<p>The MS spectra obtained by HPTLC—MS analysis of the STS from Bohemian knotweed rhizomes on HPTLC diol F<sub>254S</sub> plate pre-developed and developed with acetonitrile. The bolded <span class="html-italic">m/z</span> values in the MS spectra belong to B-type proanthocyanidins and their gallates eluted from the underivatized part of the plate with acetonitrile–methanol (2:1, <span class="html-italic">v/v</span>). A narrow derivatized (DMACA reagent) part of the plate with blue-colored proanthocyanidins zones was used for the proper positioning of the elution head of the TLC—MS interface.</p> Full article ">Figure 9
<p>The MS spectra obtained by HPTLC–MS analysis of STS from giant knotweed rhizomes on the HPTLC diol F<sub>254S</sub> plate pre-developed and developed with acetonitrile. The bolded <span class="html-italic">m/z</span> values in the MS spectra belong to B-type proan thocyanidins and their gallates eluted from the underivatized part of the plate with acetonitrile–methanol (2:1, <span class="html-italic">v/v</span>). A narrow derivatized (DMACA reagent) part of the plate with blue-colored proanthocyanidins zones was used for the proper positioning of the elution head of the TLC–MS interface.</p> Full article ">
11 pages, 4051 KiB  
Article
Identification and Detection of Botryosphaeria dothidea from Kiwifruit (Actinidia chinensis) in China
by Li Wang, Hui Hou, Zengqiang Zhou, Hongtao Tu and Hongbo Yuan
Plants 2021, 10(2), 401; https://doi.org/10.3390/plants10020401 - 20 Feb 2021
Cited by 23 | Viewed by 4899
Abstract
Kiwifruit is very popular among consumers due to its high nutritional value. The increasing expansion in kiwifruit cultivation has led to the spread of rot diseases. To identify the pathogens causing kiwifruit ripe rots in China, 24 isolates were isolated from the diseased [...] Read more.
Kiwifruit is very popular among consumers due to its high nutritional value. The increasing expansion in kiwifruit cultivation has led to the spread of rot diseases. To identify the pathogens causing kiwifruit ripe rots in China, 24 isolates were isolated from the diseased fruit and wart in trees. Botryosphaeria dothidea was recognized as the pathogen causing kiwifruit ripe rot and wart in the tree through internal transcribed spacer (ITS) sequencing, pathogenicity testing, morphological and microscopic characteristics. The rapid and accurate detection of this pathogen will lead to better disease monitoring and control efforts. A loop-mediated isothermal amplification (LAMP) method was then developed to rapidly and specifically identify B. dothidea. These results offer value to further research into kiwifruit ripe rot, such as disease prediction, pathogen rapid detection, and effective disease control. Full article
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<p>Symptoms of kiwifruit soft rot. (<b>A</b>) External slightly sunken symptom (arrow) on kiwi fruit. (<b>B</b>) Wart (arrow) on kiwi stem.</p> Full article ">Figure 2
<p>Morphologic characteristics of <span class="html-italic">Botryosphaeria dothidea</span>. Bd 431 comes from the diseased fruit (<b>left</b>), Bd432 comes from the wart (<b>right</b>). (<b>A</b>) The <span class="html-italic">B. dothidea</span> phenotype following a 5-day culture period on potato dextrose agar (PDA). (<b>B</b>) Pycnidia formation of <span class="html-italic">B. dothidea</span> on PDA. (<b>C</b>) Conidial morphology of <span class="html-italic">B. dothidea</span>.</p> Full article ">Figure 3
<p>Dendrogram constructed by the neighbor-joining method showing the phylogenetic relationship (100%) between the isolate of <span class="html-italic">Botryosphaeria dothidea</span> (BD431) and <span class="html-italic">B. dothidea</span> isolate (AF027747) based on the We have checked (ITS) sequences.</p> Full article ">Figure 4
<p>Symptoms of kiwifruit inoculated by <span class="html-italic">Botryosphaeria dothidea</span>. (<b>A</b>) No external symptom (arrow) of kiwifruit artificial infection with fungi-free PDA. (<b>B</b>) External slightly sunken symptom (arrow) of kiwifruit artificial infection with <span class="html-italic">B. dothidea</span> (Bd 431 comes from the diseased fruit). (<b>C</b>) External slightly sunken symptom (arrow) of kiwifruit artificial infection with <span class="html-italic">B. dothidea</span> (Bd432 comes from the wart).</p> Full article ">Figure 5
<p>Loop-mediated isothermal amplification (LAMP) assay on detection of <span class="html-italic">Botryosphaeria dothidea</span>. 1000 × SYBR Green I color change-based LAMP product detection (<b>A</b>). Agarose gel electrophoresis-based LAMP product detection (<b>B</b>). M: DNA marker 2 k, 1: <span class="html-italic">Botryosphaeria dothidea</span> isolate from kiwifruit fruit, 2: <span class="html-italic">Botryosphaeria dothidea</span> isolate from kiwifruit stem, 3: <span class="html-italic">Botrytis cinerea</span>, 4: <span class="html-italic">Colletotrichum gloeosporioides</span>, 5: <span class="html-italic">Valsa mali</span>, 6: <span class="html-italic">Alternaria alternate</span>, 7: <span class="html-italic">Marssonina coronaria</span>, 8: water.</p> Full article ">Figure 6
<p>Assessment of LAMP assay sensitivity for the detection of <span class="html-italic">Botryosphaeria dothidea.</span> 1000 × SYBR Green I color change-based LAMP product detection (<b>A</b>). Agarose gel electrophoresis-based LAMP product detection (<b>B</b>). DNA isolated from <span class="html-italic">Botryosphaeria dothidea</span> isolate was subjected to serial 10-fold dilution (10 ng–10<sup>−6</sup> ng) and served as a template in LAMP assays. M: DNA marker 2 k, 1–7: 10 ng, 10<sup>−1</sup> ng, 10<sup>−2</sup> ng, 10<sup>−3</sup> ng, 10<sup>−4</sup> ng, 10<sup>−5</sup> ng, 10<sup>−6</sup> ng, 8: water.</p> Full article ">Figure 6 Cont.
<p>Assessment of LAMP assay sensitivity for the detection of <span class="html-italic">Botryosphaeria dothidea.</span> 1000 × SYBR Green I color change-based LAMP product detection (<b>A</b>). Agarose gel electrophoresis-based LAMP product detection (<b>B</b>). DNA isolated from <span class="html-italic">Botryosphaeria dothidea</span> isolate was subjected to serial 10-fold dilution (10 ng–10<sup>−6</sup> ng) and served as a template in LAMP assays. M: DNA marker 2 k, 1–7: 10 ng, 10<sup>−1</sup> ng, 10<sup>−2</sup> ng, 10<sup>−3</sup> ng, 10<sup>−4</sup> ng, 10<sup>−5</sup> ng, 10<sup>−6</sup> ng, 8: water.</p> Full article ">Figure 7
<p>Detection of the <span class="html-italic">Botryosphaeria dothidea</span> in tissue samples from diseased kiwi fruits via LAMP assay. 1000 × SYBR Green I color change-based LAMP product detection (<b>A</b>). Agarose gel electrophoresis-based LAMP product detection (<b>B</b>). M: DNA marker 2 k, 1: DNA from <span class="html-italic">Botryosphaeria dothidea</span> isolate mycelium, 2: DNA from diseased kiwi fruit infected with <span class="html-italic">Botryosphaeria dothidea</span> from the pathogenicity determination experiment, 3,4: DNA from diseased kiwi fruit infected with <span class="html-italic">Botryosphaeria dothidea</span> from field, 5: DNA from healthy kiwifruit fruit, 6: water.</p> Full article ">
17 pages, 2873 KiB  
Review
Non-Cannabinoid Metabolites of Cannabis sativa L. with Therapeutic Potential
by Henry Lowe, Blair Steele, Joseph Bryant, Ngeh Toyang and Wilfred Ngwa
Plants 2021, 10(2), 400; https://doi.org/10.3390/plants10020400 - 20 Feb 2021
Cited by 62 | Viewed by 10147
Abstract
The cannabis plant (Cannabis sativa L.) produces an estimated 545 chemical compounds of different biogenetic classes. In addition to economic value, many of these phytochemicals have medicinal and physiological activity. The plant is most popularly known for its two most-prominent and most-studied [...] Read more.
The cannabis plant (Cannabis sativa L.) produces an estimated 545 chemical compounds of different biogenetic classes. In addition to economic value, many of these phytochemicals have medicinal and physiological activity. The plant is most popularly known for its two most-prominent and most-studied secondary metabolites—Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Both Δ9-THC and CBD have a wide therapeutic window across many ailments and form part of a class of secondary metabolites called cannabinoids—of which approximately over 104 exist. This review will focus on non-cannabinoid metabolites of Cannabis sativa that also have therapeutic potential, some of which share medicinal properties similar to those of cannabinoids. The most notable of these non-cannabinoid phytochemicals are flavonoids and terpenes. We will also discuss future directions in cannabis research and development of cannabis-based pharmaceuticals. Caflanone, a flavonoid molecule with selective activity against the human viruses including the coronavirus OC43 (HCov-OC43) that is responsible for COVID-19, and certain cancers, is one of the most promising non-cannabinoid molecules that is being advanced into clinical trials. As validated by thousands of years of the use of cannabis for medicinal purposes, vast anecdotal evidence abounds on the medicinal benefits of the plant. These benefits are attributed to the many phytochemicals in this plant, including non-cannabinoids. The most promising non-cannabinoids with potential to alleviate global disease burdens are discussed. Full article
(This article belongs to the Special Issue Research of Bioactive Substances in Plant Extracts)
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<p>Synthesis of cannabinoids and non-cannabinoids produced by <span class="html-italic">Cannabis sativa</span> L. [<a href="#B2-plants-10-00400" class="html-bibr">2</a>].</p> Full article ">Figure 2
<p>The chemical structures of some terpenoids produced by <span class="html-italic">Cannabis sativa</span> L. (<b>a</b>.) α-pinene; (<b>b</b>.) Borneol; (<b>c</b>.) Humulene; (<b>d</b>.) β-caryophyllene; (<b>e</b>.) Linalool; (<b>f</b>.) α-Myrcene; (<b>g</b>.) D-linonene.</p> Full article ">Figure 3
<p>The chemical structures of some flavonoids produced by <span class="html-italic">Cannabis sativa</span> L. (<b>a</b>.) Cannflavin A; (<b>b</b>.) Cannflavin B; (<b>c</b>.) Flavone; (<b>d</b>.) Luteolin.</p> Full article ">Figure 4
<p>The main protein interactions of caflanone [<a href="#B39-plants-10-00400" class="html-bibr">39</a>]. Reproduced with permission from Wilfred Ngwa, Potential of Flavonoid-Inspired Phytomedicines against COVID-19, published by <span class="html-italic">Molecules</span> Open-Access Journal, 11 June 2020 [<a href="#B39-plants-10-00400" class="html-bibr">39</a>].</p> Full article ">Figure 5
<p>A comparison of the docking/binding studies results between the phytoantiviral flavonoids hesperetin, myricetin, linebacker, and caflanone [<a href="#B39-plants-10-00400" class="html-bibr">39</a>].</p> Full article ">Figure 6
<p>The structure of some fatty acids found in <span class="html-italic">C. sativa</span> L. [<a href="#B48-plants-10-00400" class="html-bibr">48</a>]. (<b>a</b>.) Caproic acid; (<b>b</b>.) Caprylic acid; (<b>c</b>.) Oleic acid; (<b>d</b>.) Eicosenoic acid; (<b>e</b>.) Palmitoleic acid.</p> Full article ">Figure 7
<p>Comparison of the fatty acid composition of edible plant oils [<a href="#B49-plants-10-00400" class="html-bibr">49</a>].</p> Full article ">Figure 8
<p>The chemical structure of cannabisativine, the first cannabinaceous alkaloid to be fully identified.</p> Full article ">Figure 9
<p>The basic structure of alanine, an amino acid.</p> Full article ">Figure 10
<p>The chemical structure of dihydroresveratrol, a hydroxylated stilbene derivative.</p> Full article ">Figure 11
<p>The chemical structures of some stilbenes and their derivates found in <span class="html-italic">C. sativa</span> L.</p> Full article ">
20 pages, 1224 KiB  
Review
Host Cell Wall Damage during Pathogen Infection: Mechanisms of Perception and Role in Plant-Pathogen Interactions
by Riccardo Lorrai and Simone Ferrari
Plants 2021, 10(2), 399; https://doi.org/10.3390/plants10020399 - 19 Feb 2021
Cited by 57 | Viewed by 10591
Abstract
The plant cell wall (CW) is a complex structure that acts as a mechanical barrier, restricting the access to most microbes. Phytopathogenic microorganisms can deploy an arsenal of CW-degrading enzymes (CWDEs) that are required for virulence. In turn, plants have evolved proteins able [...] Read more.
The plant cell wall (CW) is a complex structure that acts as a mechanical barrier, restricting the access to most microbes. Phytopathogenic microorganisms can deploy an arsenal of CW-degrading enzymes (CWDEs) that are required for virulence. In turn, plants have evolved proteins able to inhibit the activity of specific microbial CWDEs, reducing CW damage and favoring the accumulation of CW-derived fragments that act as damage-associated molecular patterns (DAMPs) and trigger an immune response in the host. CW-derived DAMPs might be a component of the complex system of surveillance of CW integrity (CWI), that plants have evolved to detect changes in CW properties. Microbial CWDEs can activate the plant CWI maintenance system and induce compensatory responses to reinforce CWs during infection. Recent evidence indicates that the CWI surveillance system interacts in a complex way with the innate immune system to fine-tune downstream responses and strike a balance between defense and growth. Full article
(This article belongs to the Special Issue The Role of Cell Wall in Plant Defense)
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<p>Overview of responses induced by cell wall damage during pathogen infection. CW, cell wall; CWDE, cell wall-degrading enzyme; CWI, cell wall integrity; PTI, pattern-triggered immunity; DAMP, Damage-Associated Molecular Pattern; BBEL, berberine bridge enzyme-like protein; oxDAMP, oxidized DAMP; POD, peroxidase; ROS, reactive oxygen species. CWDEs secreted by the pathogen degrade CW structural polysaccharides. CW damage activates the CWI perception system, mediated by dedicated sensors, triggering CWI maintenance responses, that include production of ROS mediated by membrane NADPH oxidases and apoplastic PODs, and reinforcement of the CW. Host-encoded inhibitors reduce CWDE activity, slowing down CW degradation and promoting the accumulation of CW-derived DAMPs. Perception of DAMPs by membrane-localized receptors in turn activates PTI, which leads to antimicrobial defence responses, including production of phytoalexins, PR proteins and ROS, that contribute to restrict infection. Negative and positive crosstalk between CWI and PTI fine-tune defence responses triggered by CW damage. DAMPs can be inactivated by apoplastic BBEL proteins, that oxidize CW-derived oligosaccharides, at the same time producing ROS. Some pathogens can secrete decoy proteins that bind to CWDE inhibitors.</p> Full article ">
13 pages, 1027 KiB  
Article
Somatic Embryogenesis Initiation in Sugi (Japanese Cedar, Cryptomeria japonica D. Don): Responses from Male-Fertile, Male-Sterile, and Polycross-Pollinated-Derived Seed Explants
by Tsuyoshi E. Maruyama, Saneyoshi Ueno, Yoshihisa Hosoi, Shin-Ichi Miyazawa, Hideki Mori, Takumi Kaneeda, Yukiko Bamba, Yukiko Itoh, Satoko Hirayama, Kiyohisa Kawakami and Yoshinari Moriguchi
Plants 2021, 10(2), 398; https://doi.org/10.3390/plants10020398 - 19 Feb 2021
Cited by 8 | Viewed by 3038
Abstract
This study aimed to obtain information from several embryogenic cell (EC) genotypes analyzing the factors that affect somatic embryogenesis (SE) initiation in sugi (Cryptomeria japonica, Cupressaceae) to apply them in the improvement of protocols for efficient induction of embryogenic cell lines (ECLs). [...] Read more.
This study aimed to obtain information from several embryogenic cell (EC) genotypes analyzing the factors that affect somatic embryogenesis (SE) initiation in sugi (Cryptomeria japonica, Cupressaceae) to apply them in the improvement of protocols for efficient induction of embryogenic cell lines (ECLs). The results of several years of experiments including studies on the influence of initial explant, seed collection time, and explant genotype as the main factors affecting SE initiation from male-fertile, male-sterile, and polycross-pollinated-derived seeds are described. Initiation frequencies depending on the plant genotype varied from 1.35 to 57.06%. The best induction efficiency was achieved when seeds were collected on mid-July using the entire megagametophyte as initial explants. The extrusion of ECs started approximately after 2 weeks of culture, and the establishment of ECLs was observed mostly 4 weeks after extrusion on media with or without plant growth regulators (PGRs). Subsequently, induced ECLs were maintained and proliferated on media with PGRs by 2–3-week-interval subculture routines. Although, the initial explant, collection time, and culture condition played important roles in ECL induction, the genotype of the plant material of sugi was the most influential factor in SE initiation. Full article
(This article belongs to the Special Issue Advances in Plant Regeneration)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Somatic embryogenesis (SE) initiation in sugi: (<b>A</b>) extrusion of embryogenic cells (ECs) about 2 weeks after culture initiation on media with plant growth regulators (PGRs), (<b>B</b>) EC proliferation on a medium with PGRs approximately 4 weeks after extrusion, and (<b>C</b>) germination and SE initiation on a medium with no PGRs approximately 4 weeks after culture initiation. Bars: 5 mm.</p> Full article ">Figure 2
<p>Somatic embryogenesis (SE) initiation in sugi: (<b>A</b>) embryogenic cell (EC) proliferation from whole seed explant on media with plant growth regulators (PGRs) approximately 6 weeks after culture initiation and (<b>B</b>) from seeds with coat cut lengthwise on media with PGRs approximately 4 weeks after culture initiation. Bars: 1 mm.</p> Full article ">Figure 3
<p>Proliferation of embryogenic cell lines (ECLs) with different morphological structures: (<b>A</b>) mucilaginous whitish embryogenic cells (ECs), (<b>B</b>) mucilaginous yellowish ECs, and (<b>C</b>) friable white translucent ECs. Bars: 5 mm.</p> Full article ">
17 pages, 7765 KiB  
Article
Two Korean Endemic Clematis Chloroplast Genomes: Inversion, Reposition, Expansion of the Inverted Repeat Region, Phylogenetic Analysis, and Nucleotide Substitution Rates
by Kyoung Su Choi, Young-Ho Ha, Hee-Young Gil, Kyung Choi, Dong-Kap Kim and Seung-Hwan Oh
Plants 2021, 10(2), 397; https://doi.org/10.3390/plants10020397 - 19 Feb 2021
Cited by 18 | Viewed by 3109
Abstract
Previous studies on the chloroplast genome in Clematis focused on the chloroplast structure within Anemoneae. The chloroplast genomes of Cleamtis were sequenced to provide information for studies on phylogeny and evolution. Two Korean endemic Clematis chloroplast genomes (Clematis brachyura and C. trichotoma [...] Read more.
Previous studies on the chloroplast genome in Clematis focused on the chloroplast structure within Anemoneae. The chloroplast genomes of Cleamtis were sequenced to provide information for studies on phylogeny and evolution. Two Korean endemic Clematis chloroplast genomes (Clematis brachyura and C. trichotoma) range from 159,170 to 159,532 bp, containing 134 identical genes. Comparing the coding and non-coding regions among 12 Clematis species revealed divergent sites, with carination occurring in the petD-rpoA region. Comparing other Clematis chloroplast genomes suggested that Clematis has two inversions (trnH-rps16 and rps4), reposition (trnL-ndhC), and inverted repeat (IR) region expansion. For phylogenetic analysis, 71 protein-coding genes were aligned from 36 Ranunculaceae chloroplast genomes. Anemoneae (Anemoclema, Pulsatilla, Anemone, and Clematis) clades were monophyletic and well-supported by the bootstrap value (100%). Based on 70 chloroplast protein-coding genes, we compared nonsynonymous (dN) and synonymous (dS) substitution rates among Clematis, Anemoneae (excluding Clematis), and other Ranunculaceae species. The average synonymoussubstitution rates (dS)of large single copy (LSC), small single copy (SSC), and IR genes in Anemoneae and Clematis were significantly higher than those of other Ranunculaceae species, but not the nonsynonymous substitution rates (dN). This study provides fundamental information on plastid genome evolution in the Ranunculaceae. Full article
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<p>Chloroplast genome map for two <span class="html-italic">Clematis</span> species. Genes shown outside the circle are transcribed clockwise, whereas those inside the circle are transcribed counterclockwise. Genes belonging to different functional groups are colored. The dashed area in the inner circle indicates the GC content of the genome.</p> Full article ">Figure 2
<p>Chloroplast genome sequence alignment of 12 species of <span class="html-italic">Clematis</span> with <span class="html-italic">C. brachyura</span> used as a reference. The sequence identities were calculated and visualized in mVISTA. LSC, large single copy; SSC, small single copy; IR, inverted repeat.</p> Full article ">Figure 3
<p>Comparisons of junctions (LSC to IR and IR to SSC IR region) among the chloroplast genomes of <span class="html-italic">Clematis</span>. * indicates different lengths between pairs of IRs. LSC, large single copy; SSC, small single copy; IR, inverted repeat.</p> Full article ">Figure 4
<p>Alignment of two pseudogenes in <span class="html-italic">Clematis</span>. (<b>A</b>) <span class="html-italic">ψ infAψ</span>; (<b>B</b>) <span class="html-italic">ψ rpl32</span>.</p> Full article ">Figure 5
<p>Sliding window analysis of the whole chloroplast genome for nucleotide diversity (Pi) compared among 12 <span class="html-italic">Clematis</span> species.</p> Full article ">Figure 6
<p>Maximum likelihood tree derived from 36 species and based on 77 concatenated protein-coding genes of Ranunculaceae. Bootstrap support values &gt;70% are shown on the branches. Clade of <span class="html-italic">Clematis</span> followed Lehtonene et al. [<a href="#B53-plants-10-00397" class="html-bibr">53</a>]. “-” did not include species by previous study [<a href="#B53-plants-10-00397" class="html-bibr">53</a>].</p> Full article ">Figure 7
<p>Patterns of rearrangement in the large single copy in <span class="html-italic">Ranunculus</span>. Rearrangement events are mapped on the branches.</p> Full article ">Figure 8
<p>Comparison of synonymous (<span class="html-italic">dS)</span> and nonsynonymous (<span class="html-italic">dN</span>) substitution rates among Anemoneae, <span class="html-italic">Clematis</span>, and Ranunculaceae. (<b>A</b>) Comparison of <span class="html-italic">dS;</span> (<b>B</b>) Comparison of <span class="html-italic">dN</span>. LSC, large single copy region; IR, inverted repeat region; LSC or IR, genes were located in the LSC or IR regions; SSC; small single copy region. Asterisks indicate <span class="html-italic">p</span> &lt; 0.05 (***).</p> Full article ">Figure 9
<p>Extension of inverted repeat (IR) region in Anemoneae. IR expansion shown with red line. (<b>A</b>) Type A of IR expansion in Anemoneae; (<b>B</b>) type B of IR in Ranunculaceae excluding Anemoneae); (<b>C</b>) comparison of <span class="html-italic">dN</span> and <span class="html-italic">dS</span> between type A and type B genes. Asterisks indicate <span class="html-italic">p</span> &lt; 0.05 (*) and <span class="html-italic">p</span> &lt; 0.01 (**).</p> Full article ">
12 pages, 3267 KiB  
Article
Effect of Cryopreservation on the Ex Vitro Establishment of Olive Plants Regenerated via Somatic Embryogenesis
by Fatiha Bradaï and Carolina Sánchez-Romero
Plants 2021, 10(2), 396; https://doi.org/10.3390/plants10020396 - 19 Feb 2021
Cited by 8 | Viewed by 2715
Abstract
Cryopreservation is considered the best technique for the safe, long-term conservation of embryogenic cultures. However, before integrating it into a somatic embryogenesis system, the influence of cryopreservation on the final production of plants should be investigated. The objective of this investigation was to [...] Read more.
Cryopreservation is considered the best technique for the safe, long-term conservation of embryogenic cultures. However, before integrating it into a somatic embryogenesis system, the influence of cryopreservation on the final production of plants should be investigated. The objective of this investigation was to evaluate the effect of cryopreservation on the regeneration performance of olive embryogenic cultures as well as on the quality of the plants obtained and their response to ex vitro establishment. In order to analyze the influence of the genotype, all the investigations were carried out in two genetically distinct embryogenic lines. The results obtained revealed no variation in the regeneration potential or the quality of the regenerated plants due to cryopreservation. The subsequent multiplication, rooting, and acclimatization steps were not influenced by cryopreservation either, although a significant genotype × cryopreservation interaction was found for shoot length during the multiplication step. The genotype played an important role, determining the quality of the regenerated plants and some aspects of the multiplication and rooting phases. This investigation revealed that the droplet-vitrification procedure optimized for the cryopreservation of olive somatic embryos can be efficiently used for the long-term conservation of olive embryogenic lines. Full article
(This article belongs to the Special Issue Somatic Embryogenesis in Olive)
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<p>Plantlets regenerated from (<b>A</b>,<b>C</b>) control and (<b>B</b>,<b>D</b>) cryopreserved embryogenic cultures of the lines T1 (<b>A</b>,<b>B</b>) and P5 (<b>C</b>,<b>D</b>). Bar = 1 cm.</p> Full article ">Figure 2
<p>Regeneration potential of control and cryopreserved embryogenic cultures of the lines T1 and P5. Data represent the mean ± SEM. Different letters indicate significant differences by the least significant difference (LSD) test with a significance level of 0.05.</p> Full article ">Figure 3
<p>In vitro multiplication of olive plants derived from (<b>A</b>,<b>C</b>) control and (<b>B</b>,<b>D</b>) cryopreserved embryogenic cultures of the lines T1 (<b>A</b>,<b>B</b>) and P5 (<b>C</b>,<b>D</b>). Bar = 1 cm.</p> Full article ">Figure 4
<p>Rooting percentage of olive shoots derived from control and cryopreserved embryogenic cultures of the lines T1 and P5. Different letters indicate significant differences by the R × C test, with a significance level of 0.05.</p> Full article ">Figure 5
<p>Rooting of olive shoots derived from (<b>A</b>,<b>C</b>) control and (<b>B</b>,<b>D</b>) cryopreserved embryogenic cultures of the lines T1 (<b>A</b>,<b>B</b>) and P5 (<b>C</b>,<b>D</b>). Bar = 1 cm.</p> Full article ">Figure 6
<p>Acclimatization of olive plants developed from (<b>A</b>,<b>C</b>) control and (<b>B</b>,<b>D</b>) cryopreserved embryogenic cultures of the lines T1 (<b>A</b>,<b>B</b>) and P5 (<b>C</b>,<b>D</b>). Bar = 1 cm.</p> Full article ">
13 pages, 3143 KiB  
Article
Genetic Diversity Assessment and Cultivar Identification of Cucumber (Cucumis sativus L.) Using the Fluidigm Single Nucleotide Polymorphism Assay
by Girim Park, Yunseo Choi, Jin-Kee Jung, Eun-Jo Shim, Min-young Kang, Sung-Chur Sim, Sang-Min Chung, Gung Pyo Lee and Younghoon Park
Plants 2021, 10(2), 395; https://doi.org/10.3390/plants10020395 - 19 Feb 2021
Cited by 14 | Viewed by 3956
Abstract
Genetic diversity analysis and cultivar identification were performed using a core set of single nucleotide polymorphisms (SNPs) in cucumber (Cucumis sativus L.). For the genetic diversity study, 280 cucumber accessions collected from four continents (Asia, Europe, America, and Africa) by the National [...] Read more.
Genetic diversity analysis and cultivar identification were performed using a core set of single nucleotide polymorphisms (SNPs) in cucumber (Cucumis sativus L.). For the genetic diversity study, 280 cucumber accessions collected from four continents (Asia, Europe, America, and Africa) by the National Agrobiodiversity Center of the Rural Development Administration in South Korea and 20 Korean commercial F1 hybrids were genotyped using 151 Fluidigm SNP assay sets. The heterozygosity of the SNP loci per accession ranged from 4.76 to 82.76%, with an average of 32.1%. Population genetics analysis was performed using population structure analysis and hierarchical clustering (HC), which indicated that these accessions were classified mainly into four subpopulations or clusters according to their geographical origins. The subpopulations for Asian and European accessions were clearly distinguished from each other (FST value = 0.47), while the subpopulations for Korean F1 hybrids and Asian accessions were closely related (FST = 0.34). The highest differentiation was observed between American and European accessions (FST = 0.41). Nei’s genetic distance among the 280 accessions was 0.414 on average. In addition, 95 commercial F1 hybrids of three cultivar groups (Baekdadagi-, Gasi-, and Nakhap-types) were genotyped using 82 Fluidigm SNP assay sets for cultivar identification. These 82 SNPs differentiated all cultivars, except seven. The heterozygosity of the SNP loci per cultivar ranged from 12.20 to 69.14%, with an average of 34.2%. Principal component analysis and HC demonstrated that most cultivars were clustered based on their cultivar groups. The Baekdadagi- and Gasi-types were clearly distinguished, while the Nakhap-type was closely related to the Baekdadagi-type. Our results obtained using core Fluidigm SNP assay sets provide useful information for germplasm assessment and cultivar identification, which are essential for breeding and intellectual right protection in cucumber. Full article
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<p>Scatter plots showing genotype calls for the single-nucleotide polymorphism (SNP) assay sets P002, P101, and P118 from the Fluidigm EP1<sup>TM</sup> assay. Colored dots indicate SNP marker genotypes of the 280 cucumber accessions (<b>A</b>) and 95 commercial F1 hybrid cultivars (<b>B</b>). Red, blue, and green dots indicate XX (homozygote), YY (homozygote), and XY (heterozygote) genotypes, respectively. Gray and black dots indicate no call and no template control (NTC), respectively.</p> Full article ">Figure 2
<p>Distribution of the heterozygous marker genotype rate for the 280 accessions from the National Agrobiodiversity Center (NAC) (<b>A</b>) and 95 commercial F1 hybrids (<b>B</b>).</p> Full article ">Figure 3
<p>Population structure analysis of 300 cucumber accessions using 151 single-nucleotide polymorphism (SNP) assay sets. Population structure determined using an admixture-based clustering model. (<b>A</b>) Plot of delta K values with K ranging from 2 to 10 in the STRUCTURE analysis. (<b>B</b>) Population structure analysis results of cucumber accessions with K = 2 and (<b>C</b>) K = 4. Each accession is represented by a vertical bar. Each color represents one ancestral population, and the length of each colored segment of each vertical bar represents the proportion contributed by ancestral populations.</p> Full article ">Figure 4
<p>Unweighted pair-group method with arithmetic average (UPGMA) tree based on the genetic distance reported by Cavalli-Sforza and Edwards [<a href="#B32-plants-10-00395" class="html-bibr">32</a>] for 300 cucumber accession using 151 SNP assay sets.</p> Full article ">Figure 5
<p>Principal component analysis (PCA) of the 95 commercial cucumber F1 hybrids using 82 single nucleotide polymorphism (SNP) assay sets.</p> Full article ">Figure 6
<p>Hierarchical clustering based on Nei’s genetic distance of 95 commercial cucumber F<sub>1</sub> hybrids using 82 single-nucleotide polymorphism (SNP) assay sets.</p> Full article ">
10 pages, 1172 KiB  
Article
Polysulfides Applied as Formulated Garlic Extract to Protect Tomato Plants against the Root-Knot Nematode Meloidogyne incognita
by Reinhard Eder, Erika Consoli, Jürgen Krauss and Paul Dahlin
Plants 2021, 10(2), 394; https://doi.org/10.3390/plants10020394 - 18 Feb 2021
Cited by 21 | Viewed by 4299
Abstract
The devastating root-knot nematode Meloidogyne incognita can cause severe damage to field and greenhouse crops. Due to high economic losses, alternative products are essential to replace banned or strictly regulated nematicides that affect human health and/or the environment. Garlic based products have been [...] Read more.
The devastating root-knot nematode Meloidogyne incognita can cause severe damage to field and greenhouse crops. Due to high economic losses, alternative products are essential to replace banned or strictly regulated nematicides that affect human health and/or the environment. Garlic based products have been previously investigated as environmentally friendly nematicides and their active substances, diallyl polysulfides exist as formulated nematicides on the market. We tested the garlic-based nematicide NEMguard® DE as protective of tomato roots. In vitro evaluation of the lethal concentration (LC) showed strong nematicidal activity with LC50 of 0.8 mg/mL after 96 h and LC90 of 1.5 mg/mL. NEMguard® DE showed protective effect against M. incognita as a single application in small pots and a second application further reduced root galling, significantly. Large greenhouse trials were carried out in two consecutive years to test single and monthly applications of NEMguard® DE. In both years, no controlling effect could be observed on M.incognita. We assume that the silt content of the loamy sandy soil used had an effect on the polysulfides, inhibiting their nematicidal effect. We conclude that further experiments are necessary to investigate the nematicidal potential of NEMguard® DE under different soil compositions or as a different formulation. Full article
(This article belongs to the Special Issue Natural Products for a Sustainable Control of Phytoparasitic Nematodes)
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<p>Lethal concentration (LC) LC<sub>50</sub> and LC<sub>90</sub> of NEMguard<sup>®</sup> DE solubilized in water on <span class="html-italic">Meloidogyne incognita</span> second stage juveniles (J2) over 24 h, 48 h and 96 h of exposure. Values are means of <span class="html-italic">n</span> = 3.</p> Full article ">Figure 2
<p>Tomato root gall formation (<b>A</b>,<b>C</b>) and <span class="html-italic">Meloidogyne incognita</span> juvenile second stage (J2) soil population (<b>B</b>,<b>D</b>) development in the large-scale greenhouse trial over 10 (early), 15 (mid) and 23 (end) weeks testing NEMguard<sup>®</sup> DE applied before planting (NEMguard 1) and applied before planting followed by a monthly application (NEMguard 2). Suspensions containing approximately 4600 (2019) or 4500 (2020) <span class="html-italic">M. incognita</span> eggs/J2 were inoculated per pot. Values for the gall index (GI) according to Zeck [<a href="#B25-plants-10-00394" class="html-bibr">25</a>] and J2 populations are means of <span class="html-italic">n</span> = 4 (early and mid) and <span class="html-italic">n</span> = 8 (end), respectively. No significant difference according to one-way ANOVA with post-hoc Tukey HSD test among the treatments and the positive control (<span class="html-italic">p</span> ≤ 0.05). Positive (p) control = control with <span class="html-italic">M. incognita</span>, negative (n) control = soil free of <span class="html-italic">M. incognita.</span>.</p> Full article ">
18 pages, 688 KiB  
Article
Validation of Qualitative Broth Volatilization Checkerboard Method for Testing of Essential Oils: Dual-Column GC–FID/MS Analysis and In Vitro Combinatory Antimicrobial Effect of Origanum vulgare and Thymus vulgaris against Staphylococcus aureus in Liquid and Vapor Phases
by Marie Netopilova, Marketa Houdkova, Klara Urbanova, Johana Rondevaldova and Ladislav Kokoska
Plants 2021, 10(2), 393; https://doi.org/10.3390/plants10020393 - 18 Feb 2021
Cited by 9 | Viewed by 3913
Abstract
Combinatory action of antimicrobial agents such as essential oils (EOs) show to be an effective strategy to overcome the problem with increasing antibiotic resistance of microorganisms, including Staphylococcus aureus. The objective of this study was to evaluate in vitro antimicrobial interactions between [...] Read more.
Combinatory action of antimicrobial agents such as essential oils (EOs) show to be an effective strategy to overcome the problem with increasing antibiotic resistance of microorganisms, including Staphylococcus aureus. The objective of this study was to evaluate in vitro antimicrobial interactions between Origanum vulgare and Thymus vulgaris EOs against various S.aureus strains in both liquid and vapor phases using the broth volatilization checkerboard method. Fractional inhibitory concentrations (FICs) were determined for both liquid and vapor phases, and the composition of EOs was analyzed by gas chromatography-mass spectrometry using dual-column/dual-detector gas chromatograph. Results of oregano and thyme EOs combination showed additive effects against all S. aureus strains in both phases. In several cases, sums of FICs were lower than 0.6, which can be considered a strong additive interaction. The lowest FICs obtained were 0.53 in the liquid phase and 0.59 in the gaseous phase. Chemical analysis showed that both EOs were composed of many compounds, including carvacrol, thymol, γ-terpinene, and p-cymene. This is the first report on oregano and thyme EOs interactions against S. aureus in the vapor phase. It also confirms the accuracy of the broth volatilization checkerboard method for the evaluation of combinatory antimicrobial effects of EOs in the vapor phase. Full article
(This article belongs to the Special Issue Essential Oils of Plants (Chemical Composition, Variation and Properties))
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Isobolograms of the interactions between <span class="html-italic">Origanum vulgare</span> and <span class="html-italic">Thymus vulgaris</span> binary combinations against <span class="html-italic">Staphylococcus aureus</span> strains in vapor and liquid phases. Additivity (ΣFIC &gt; 0.5 and ≤ 1); synergy (ΣFIC ≤ 0.5).</p> Full article ">
16 pages, 1647 KiB  
Article
Evaluation of African Maize Cultivars for Resistance to Fall Armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) Larvae
by Xavier Chiriboga Morales, Amanuel Tamiru, Islam S. Sobhy, Toby J. A. Bruce, Charles A. O. Midega and Zeyaur Khan
Plants 2021, 10(2), 392; https://doi.org/10.3390/plants10020392 - 18 Feb 2021
Cited by 26 | Viewed by 5827
Abstract
The fall armyworm (FAW) has recently invaded and become an important pest of maize in Africa causing yield losses reaching up to a third of maize annual production. The present study evaluated different aspects of resistance of six maize cultivars, cropped by farmers [...] Read more.
The fall armyworm (FAW) has recently invaded and become an important pest of maize in Africa causing yield losses reaching up to a third of maize annual production. The present study evaluated different aspects of resistance of six maize cultivars, cropped by farmers in Kenya, to FAW larvae feeding under laboratory and field conditions. We assessed the arrestment and feeding of FAW neonate larvae in no-choice and choice experiments, development of larvae-pupae, food assimilation under laboratory conditions and plant damage in a field experiment. We did not find complete resistance to FAW feeding in the evaluated maize cultivars, but we detected differences in acceptance and preference when FAW larvae were given a choice between certain cultivars. Moreover, the smallest pupal weight and the lowest growth index were found on ’SC Duma 43′ leaves, which suggests an effect of antibiosis of this maize hybrid against FAW larvae. In contrast, the highest growth index was recorded on ‘Rachar’ and the greatest pupal weight was found on ‘Nyamula’ and ‘Rachar’. The density of trichomes on the leaves of these maize cultivars seems not to be directly related to the preference of neonates for feeding. Plant damage scores were not statistically different between cultivars in the field neither under natural nor artificial infestation. However, plant damage scores in ‘Nyamula’ and ‘Jowi’ tended to be lower in the two last samplings of the season compared to the two initial samplings under artificial infestation. Our study provides insight into FAW larval preferences and performance on some African maize cultivars, showing that there are differences between cultivars in these variables; but high levels of resistance to larvae feeding were not found. Full article
(This article belongs to the Section Plant Protection and Biotic Interactions)
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<p>Number of fall armyworm (FAW) larvae (arrestment) on leaf cuts of maize cultivars (average ± SEM; n = 10) in a no-choice experiment after 24 h (<b>a</b>) and after 48 h (<b>b</b>). Different letters represent significant differences based on Tukey HSD test (5%) and (ns) represents no significant differences.</p> Full article ">Figure 2
<p>Consumed leaf area (cm<sup>2</sup>; average ± SEM; n = 10) in maize cultivars by FAW neonate larvae in a no-choice experiment after 24 h (<b>a</b>) and 48 h (<b>b</b>). Different letters represent significant differences based on Tukey HSD test (5%) and (ns) represents no significant differences.</p> Full article ">Figure 3
<p>Number of FAW larvae that settled on leaf cuts of different combinations of maize cultivars in a two-choice-experiment (<b>a</b>) after 24 h and (<b>b</b>) after 48 h. Asterisks represent significant differences (* <span class="html-italic">p</span> ≤ 0.05; ** <span class="html-italic">p</span> ≤ 0.01) and (ns) represents no significant difference between cultivars (n = 6), based on Chi-square test.</p> Full article ">Figure 4
<p>Consumed leaf area (cm<sup>2</sup>; average ± SEM; n = 6) of different combinations of maize cultivars by FAW neonate larvae in a two-choice experiment (<b>a</b>) after 24 h and (<b>b</b>) after 48 h of feeding. Asterisks represent significant differences (* <span class="html-italic">p</span> ≤ 0.05; ** <span class="html-italic">p</span> ≤ 0.01) and (ns) represents no significant differences, based on Paired <span class="html-italic">t</span>-test.</p> Full article ">Figure 5
<p>Larval weight (mean ± SEM; n = 10) of FAW developed on different maize cultivars at two time points. Asterisks represent significant differences (* <span class="html-italic">p</span> ≤ 0.05; ** <span class="html-italic">p</span> ≤ 0.01) between time-points and (ns) represents no significant differences between time-points. Lowercase different letters represent significant differences between maize cultivars within Day 9. Uppercase letters represent no significant differences between cultivars within Day 12, based on Holm–Sidak method (Two-way ANOVA).</p> Full article ">Figure 6
<p>Pupal weight (mean ± SEM; n = 10) of FAW when their larval stage developed on several maize cultivars at day 15. Different letters represent significant differences based on Tukey HSD test (5%).</p> Full article ">Figure 7
<p>Number of trichomes (mean ± SE; n = 10) in 0.25 cm<sup>2</sup> of leaves of different maize cultivars. Different letters above bars represent significant differences between cultivars based on Tukey HSD test (5%).</p> Full article ">Figure 8
<p>Plant damage scores (mean ± SE, n = 3) for six maize cultivars in cropping conditions across four samplings (sampling 1: 20 days after sowing, sampling 2: 40 days after sowing, sampling 3: 60 days after sowing, sampling 4: 80 days after sowing) in plots: (<b>a</b>) naturally infested (<b>b</b>) artificially infested.</p> Full article ">
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