Activate Plant Defense Research Articles

Ecology, Biology and Management of Fusarium Wilt in Chickpea (Cicer arietinum L.): A Review

Chickpea (Cicer arietinum L.) is one of the most important legume crop in the world and mostly cultivated during the cool winter season (Nov-Feb) in India. In recent, chickpea production and yield drastically reduced in India due to abnormal monsoonal rainfall distribution and soil conditions has been changed due to several improper management of fields and especially soil borne disease like wilt. On regularly, Fusarium wilt incidence occurring early sown cultivars. The wilt incidence occurred during 18-35 days on ramification stage, so the plant loses their reproduction stage and yield also retarded. Several strategies were applied in management of wilt but the pathogen (F. oxysporum f. sp. ciceris) recovered their virulence ability and broke the host resistance. Continuously screened the selection of resistant lines, combined application of biocontrol treatments, plant defense activators and fungicides recorded the highest yield with least incidence of wilt.

Full-Length Transcriptional Analysis of the Same Soybean Genotype With Compatible and Incompatible Reactions to Heterodera glycines Reveals Nematode Infection Activating Plant Defense Response.

Full-length transcriptome sequencing with long reads is a powerful tool to analyze transcriptional and post-transcriptional events; however, it has not been applied on soybean (Glycine max). Here, a comparative full-length transcriptome analysis was performed on soybean genotype 09-138 infected with soybean cyst nematode (SCN, Heterodera glycines) race 4 (SCN4, incompatible reaction) and race 5 (SCN5, compatible reaction) using Oxford Nanopore Technology. Each of 9 full-length samples collected 8 days post inoculation with/without nematodes generated an average of 6.1 GB of clean data and a total of 65,038 transcript sequences. After redundant transcripts were removed, 1,117 novel genes and 41,096 novel transcripts were identified. By analyzing the sequence structure of the novel transcripts, a total of 28,759 complete open reading frame (ORF) sequences, 5,337 transcription factors, 288 long non-coding RNAs, and 40,090 novel transcripts with function annotation were predicted. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of differentially expressed genes (DEGs) revealed that growth hormone, auxin-activated signaling pathway and multidimensional cell growth, and phenylpropanoid biosynthesis pathway were enriched by infection with both nematode races. More DEGs associated with stress response elements, plant-hormone signaling transduction pathway, and plant–pathogen interaction pathway with more upregulation were found in the incompatible reaction with SCN4 infection, and more DEGs with more upregulation involved in cell wall modification and carbohydrate bioprocess were detected in the compatible reaction with SCN5 infection when compared with each other. Among them, overlapping DEGs with a quantitative difference was triggered. The combination of protein–protein interaction with DEGs for the first time indicated that nematode infection activated the interactions between transcription factor WRKY and VQ (valine-glutamine motif) to contribute to soybean defense. The knowledge of the SCN–soybean interaction mechanism as a model will present more understanding of other plant–nematode interactions.

Inferring the Significance of the Polyamine Metabolism in the Phytopathogenic Bacteria Pseudomonas syringae: A Meta-Analysis Approach.

To succeed in plant invasion, phytopathogenic bacteria rely on virulence mechanisms to subvert plant immunity and create favorable conditions for growth. This process requires a precise regulation in the production of important proteins and metabolites. Among them, the family of compounds known as polyamines have attracted considerable attention as they are involved in important cellular processes, but it is not known yet how phytopathogenic bacteria regulate polyamine homeostasis in the plant environment. In the present study, we performed a meta-analysis of publicly available transcriptomic data from experiments conducted on bacteria to begin delving into this topic and better understand the regulation of polyamine metabolism and its links to pathogenicity. We focused our research on Pseudomonas syringae, an important phytopathogen that causes disease in many economically valuable plant species. Our analysis discovered that polyamine synthesis, as well as general gene expression activation and energy production are induced in the early stages of the disease. On the contrary, synthesis of these compounds is inhibited whereas its transport is upregulated later in the process, which correlates with the induction of virulence genes and the metabolism of nitrogen and carboxylic acids. We also found that activation of plant defense mechanisms affects bacterial polyamine synthesis to some extent, which could reduce bacterial cell fitness in the plant environment. Furthermore, data suggest that a proper bacterial response to oxidative conditions requires a decrease in polyamine production. The implications of these findings are discussed.

Signatures of plant defense response specificity mediated by herbivore-associated molecular patterns in legumes.

Chewing herbivores activate plant defense responses through a combination of mechanical wounding and elicitation by herbivore-associated molecular patterns (HAMPs). HAMPs are wound response amplifiers; however, specific defense outputs may also exist that strictly require HAMP-mediated defense signaling. To investigate HAMP-mediated signaling and defense responses, we characterized cowpea (Vigna unguiculata) transcriptome changes following elicitation by inceptin, a peptide HAMP common in Lepidoptera larvae oral secretions. Following inceptin treatment, we observed large-scale reprogramming of the transcriptome consistent with three different response categories: (i) amplification of mechanical wound responses, (ii) temporal extension through accelerated or prolonged responses, and (iii) examples of inceptin-specific elicitation and suppression. At both early and late timepoints, namely 1 and 6 h, large sets of transcripts specifically accumulated following inceptin elicitation. Further early inceptin-regulated transcripts were classified as reversing changes induced by wounding alone. Within key signaling- and defense-related gene families, inceptin-elicited responses included target subsets of wound-induced transcripts. Transcripts displaying the largest inceptin-elicited fold changes included transcripts encoding terpene synthases (TPSs) and peroxidases (POXs) that correspond with induced volatile production and increased POX activity in cowpea. Characterization of inceptin-elicited cowpea defenses via heterologous expression in Nicotiana benthamiana demonstrated that specific cowpea TPSs and POXs were able to confer terpene emission and the reduced growth of beet armyworm (Spodoptera exigua) herbivores, respectively. Collectively, our present findings in cowpea support a model where HAMP elicitation both amplifies concurrent wound responses and specifically contributes to the activation of selective outputs associated with direct and indirect antiherbivore defenses.

The Fungal Endophyte Penicillium olsonii ML37 Reduces Fusarium Head Blight by Local Induced Resistance in Wheat Spikes

The fungal endophyte Penicillium olsonii ML37 is a biocontrol agent of Fusarium head blight in wheat (caused by Fusarium graminearum), which has shown a limited direct inhibition of fungal growth in vitro. We used RNA-seq and LC-MS/MS analyses to elucidate metabolic interactions of the three-way system Penicillium–wheat–Fusarium in greenhouse experiments. We demonstrated that P. olsonii ML37 colonises wheat spikes and transiently activates plant defence mechanisms, as pretreated spikes show a faster and stronger expression of the defence metabolism during the first 24 h after pathogen inoculation. This effect was transient and the expression of the same genes was lower in the pathogen-infected spikes than in those infected by P. olsonii alone. This response to the endophyte includes the transcriptional activation of several WRKY transcription factors. This early activation is associated with a reduction in FHB symptoms and significantly lower levels of the F. graminearum metabolites 15-acetyl-DON and culmorin. An increase in the Penicillium-associated metabolite asperphanamate confirms colonisation by the endophyte. Our results suggest that the mode of action used by P. olsonii ML37 is via a local defence activation in wheat spikes, and that this fungus has potential as a novel biological alternative in wheat disease control.

Drenched Silicon Suppresses Disease and Insect Pests in Coffee Plant Grown in Controlled Environment by Improving Physiology and Upregulating Defense Genes.

Plant disease and insect pests are major limiting factors that reduce crop production worldwide. The ornamental indoor cultivation cash crop dwarf coffee Punica arabica ‘Pacas’ is also troubled by these issues. Silicon (Si) is one of the most abundant elements in the lithosphere and positively impacts plant health by effectively mitigating biotic and abiotic stresses. Several studies have shown that Si activates plant defense systems, although the specific nature of the involvement of Si in biochemical processes that lead to resistance is unclear. In our study, Si significantly promoted the growth and development of dwarf coffee seedlings grown in plant growth chambers. More than that, through natural infection, Si suppressed disease and insect pests by improving physiology (e.g., the strong development of the internal structures of roots, stems, and leaves; higher photosynthetic efficiency; more abundant organic matter accumulation; the promotion of root activity; the efficient absorption and transfer of mineral elements; and various activated enzymes) and up-regulating defense genes (CaERFTF11 and CaERF13). Overall, in agriculture, Si may potentially contribute to global food security and safety by assisting in the creation of enhanced crop types with optimal production as well by mitigating plant disease and insect pests. In this sense, Si is a sustainable alternative in agricultural production.

Phytomelatonin as a central molecule in plant disease resistance.

Melatonin is an essential phytohormone in the regulation of many plant processes, including during plant development and in response to stress. Pathogen infections cause serious damage to plants and reduce agricultural production. Recent studies indicate that melatonin plays important roles in alleviating bacterial, fungal, and viral diseases in plants and post-harvest fruits. Herein, we summarize information related to the effects of melatonin on plant disease resistance. Melatonin, reactive oxygen species, and reactive nitrogen species form a complex loop in plant-pathogen interaction to regulate plant disease resistance. Moreover, crosstalk of melatonin with other phytohormones including salicylic acid, jasmonic acid, auxin, and abscisic acid further activates plant defense genes. Melatonin plays an important role not only in plant immunity but also in alleviating pathogenicity. We also summarize the known processes by which melatonin mediates pathogenicity via negatively regulating the expression levels of genes related to cell viability as well as virulence-related genes. The multiple mechanisms underlying melatonin influences on both plant immunity and pathogenicity support the recognition of the essential nature of melatonin in plant-pathogen interactions, highlighting phytomelatonin as a critical molecule in plant immune responses.

Effect of Methyl Jasmonate in Gene Expression, and in Hormonal and Phenolic Profiles of Holm Oak Embryogenic Lines Before and After Infection With Phytophthora cinnamomi.

The dieback syndrome affecting Quercus ilex and other oak species impels the search for tolerant plant genotypes, as well as methods of plant immunization against such infections. Elicitation treatments can be an effective strategy to activate plant defense response and embryogenic lines represent a promising tool to generate new tolerant genotypes and also to study early markers involved in defense response. The aim of the presented work was to investigate changes in gene expression, and in hormonal and phenolic profiles induced in three holm oak embryogenic lines (ELs) elicited with methyl jasmonate (MeJA) before and after infection with the oomycete Phytophthora cinnamomi, which is the main biotic agent involved in this pathogenic process. The three ELs, derived from three genotypes, showed different basal profiles in all tested parameters, noting that the VA5 naïve genotype from a scape tree was characterized by a basal higher expression in NADPH-dependent cinnamyl alcohol dehydrogenase (CAD) and chalcone synthase (CHS) genes and also by higher caffeic acid content. Our work also identifies changes triggered by MeJA elicitation in holm oak embryogenic lines, such as increases in ABA and JA contents, as well as in levels of most of the determined phenolic compounds, especially in caffeic acid in Q8 and E00 ELs, but not in their biosynthesis genes. Irrespective of the EL, the response to oomycete infection in holm oak elicited plant material was characterized by a further increase in JA. Since JA and phenols have been described as a part of the Q. ilex defense response against P. cinnamomi, we propose that MeJA may act as an induced resistance (IR) stimulus and that in our embryogenic material induced both direct (detected prior to any challenge) and primed (detected after subsequent challenge) defense responses.

Nep1-Like Proteins From the Biocontrol Agent Pythium oligandrum Enhance Plant Disease Resistance Independent of Cell Death and Reactive Oxygen Species

Microbial necrosis and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs) act as cytolytic toxins and immunogenic patterns in plants. Our previous work shows that cytolytic NLPs (i.e., PyolNLP5 and PyolNLP7) from the biocontrol agent Pythium oligandrum enhance plant resistance against Phytophthora pathogens by inducing the expression of plant defensins. However, the relevance between PyolNLP-induced necrosis and plant resistance activation is still unclear. Here, we find that the necrosis-inducing activity of PyolNLP5 requires amino acid residues D127 and E129 within the conserved “GHRHDLE” motif. However, PyolNLP5-mediated plant disease resistance is irrelevant to its necrosis-inducing activity and the accumulation of reactive oxygen species (ROS). Furthermore, we reveal the positive role of non-cytotoxic PyolNLPs in enhancing plant resistance against Phytophthora pathogens and the fugal pathogen Sclerotinia sclerotiorum. Similarly, non-cytotoxic PyolNLPs also activate plant defense in a cell death-independent manner and induce defensin expression. The functions of non-cytotoxic PyolNLP13/14 rely on their conserved nlp24-like peptide pattern. Synthetic Pyolnlp24s derived from both cytotoxic and non-cytotoxic PyolNLPs can induce plant defensin expression. Unlike classic nlp24, Pyolnlp24s lack the ability of inducing ROS burst in plants with the presence of Arabidopsis nlp24 receptor RLP23. Taken together, our work demonstrates that PyolNLPs enhance plant resistance in an RLP23-independent manner, which requires the conserved nlp24-like peptide pattern but is uncoupled with ROS burst and cell death.

Comparative genomics of plant pathogenic Diaporthe species and transcriptomics of Diaporthe caulivora during host infection reveal insights into pathogenic strategies of the genus

BackgroundDiaporthe caulivora is a fungal pathogen causing stem canker in soybean worldwide. The generation of genomic and transcriptomic information of this ascomycete, together with a comparative genomic approach with other pathogens of this genus, will contribute to get insights into the molecular basis of pathogenicity strategies used by D. caulivora and other Diaporthe species.ResultsIn the present work, the nuclear genome of D. caulivora isolate (D57) was resolved, and a comprehensive annotation based on gene expression and genomic analysis is provided. Diaporthe caulivora D57 has an estimated size of 57,86 Mb and contains 18,385 predicted protein-coding genes, from which 1501 encode predicted secreted proteins. A large array of D. caulivora genes encoding secreted pathogenicity-related proteins was identified, including carbohydrate-active enzymes (CAZymes), necrosis-inducing proteins, oxidoreductases, proteases and effector candidates. Comparative genomics with other plant pathogenic Diaporthe species revealed a core secretome present in all Diaporthe species as well as Diaporthe-specific and D. caulivora-specific secreted proteins. Transcriptional profiling during early soybean infection stages showed differential expression of 2659 D. caulivora genes. Expression patterns of upregulated genes and gene ontology enrichment analysis revealed that host infection strategies depends on plant cell wall degradation and modification, detoxification of compounds, transporter activities and toxin production. Increased expression of effectors candidates suggests that D. caulivora pathogenicity also rely on plant defense evasion. A high proportion of the upregulated genes correspond to the core secretome and are represented in the pathogen-host interaction (PHI) database, which is consistent with their potential roles in pathogenic strategies of the genus Diaporthe.ConclusionsOur findings give novel and relevant insights into the molecular traits involved in pathogenicity of D. caulivora towards soybean plants. Some of these traits are in common with other Diaporthe pathogens with different host specificity, while others are species-specific. Our analyses also highlight the importance to have a deeper understanding of pathogenicity functions among Diaporthe pathogens and their interference with plant defense activation.

Specialist Aphid Feeding Causes Local Activation of Salicylic and Jasmonic Acid Signaling in Arabidopsis Veins.

Aphids, the phloem sap feeders, probe into leaf tissues and activate a complex network of plant defense responses. Phytohormonal signaling plays a major role in this network; however, the dynamics of the signal spreading is yet to be clarified. Despite the growing knowledge about transcriptomic changes upon infestation, results often differ due to sampling, varying strongly between the tissues collected at the single feeding site, individual leaves, pooled infested leaves, or whole plant rosettes. This study focuses on activation of salicylic acid (SA) and jasmonic acid (JA) signals in Arabidopsis leaves during infestation by cabbage aphid (Brevicoryne brassicae) in high spatio-temporal resolution. We used genetically encoded fluorescent biosensors, histochemistry, and quantitative reverse transcription-PCR to precisely map activation of distinct branches of phytohormonal signaling. We found a rapid induction of SA and JA signaling markers in cells surrounding stylet puncture, colocalizing with callose deposition. For both PR1 and JAZ10, we detected activation at 24 h postinfestation (hpi), increasing and spreading along the veins until 72 hpi and, to a lesser extent, within the epidermal pavement cells. The SA signaling wave appeared in parallel with JA-associated signaling and continued to increase in time. Our results first show a local activation of SA- and JA-related responses after stylet penetration of Arabidopsis leaves and bring a detailed insight into the spatio-temporal complexity of plant defense activation during specialist aphid attack.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Eliciting Plant Defenses Through Herbivore-Induced Plant Volatiles’ Exposure in Sweet Peppers

Insect herbivory activates plant defense mechanisms and releases a blend of herbivore-induced plant volatiles (HIPVs). These volatile compounds may be involved in plant-plant communication and induce defense response in undamaged plants. In this work, we investigated whether the exposure of sweet pepper plants to HIPVs [(Z)-3-hexenol, (Z)-3-hexenyl acetate, (Z)-3-hexenyl propanoate, (Z)-3-hexenyl butanoate, hexyl butanoate, methyl salicylate and methyl jasmonate] activates the sweet pepper immune defense system. For this, healthy sweet pepper plants were individually exposed to the each of the above mentioned HIPVs over 48 h. The expression of jasmonic acid and salicylic acid related genes was quantified. Here, we show that all the tested volatiles induced plant defenses by upregulating the jasmonic acid and salicylic acid signaling pathway. Additionally, the response of Frankliniella occidentalis, a key sweet pepper pest, and Orius laevigatus, the main natural enemy of F. occidentalis, to HIPV-exposed sweet pepper plants were studied in a Y-tube olfactometer. Only plants exposed to (Z)-3-hexenyl propanoate and methyl salicylate repelled F. occidentalis whereas O. laevigatus showed a strong preference to plants exposed to (Z)-3-hexenol, (Z)-3-hexenyl propanoate, (Z)-3-hexenyl butanoate, methyl salicylate and methyl jasmonate. Our results show that HIPVs act as elicitors to sweet pepper plant defenses by enhancing defensive signaling pathways. We anticipate our results to be a starting point for integrating HIPVs-based approaches in sweet pepper pest management systems which may provide a sustainable strategy to manage insect pests in horticultural plants.

Effect of seed priming with plant defence activators on growth parameters and disease incidence in bell pepper under nursery conditions

The effect of different plant defence activators on the seedling growth and disease incidence in bell pepper cv Solan Bharpur was studied under nursery conditions in the Department of Seed Science and Technology Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh laid out in randomized complete block design (RCBD) in 2019. It was observed that amongst different treatments applied as seed priming before sowing in nursery, highest emergence of 86.34, 83.25 and 82.41 per cent was recorded in treatments T5 (Salicylic acid @ 75 ppm + potassium nitrate @ 1.5% for 8 hours), T7 (Butyric acid @ 100 ppm + potassium nitrate @ 1.5%) and T4 (Potassium nitrate @ 1.5%/10 hours) respectively. At 28 and 42 days after sowing, the seedling height was significantly highest (4.62 and 12.21 cm respectively) in treatment T5. Minimum ungerminated seeds were observed in T5 (13.66%) and T7 (16.75%). Lowest incidence of damping off (5.43%) was recorded in T7. In case of viruses, the minimum incidence of 2.90 and 3.05 per cent was recorded in the seedlings raised from the seeds treated with T7 and T5 respectively. Application of salicylic acid @ 75 ppm + potassium nitrate @ 1.5 per cent for 8 hours or butyric acid @ 100 ppm + potassium nitrate @ 1.5 per cent for 4 hours as seed priming before sowing in nursery, enhanced the seedling growth parameters significantly and also reduced the incidence of diseases like damping off and viruses in bell pepper cv Solan Bharpur under nursery conditions.

Role of nanotechnology in management of plant viral diseases

Plant viral diseases cause huge economic losses and threat to sustainable agriculture. Nanotechnology is a growing technology in agronomy for the management of plant diseases. Nanoparticles can be used as nanopesticides, drug delivery agent or carriers for existing pesticides in pest management systems. Nanoparticles increase the disease resistance of plants by activating plant defense mechanisms or by deactivating microbes. Antiviral assay of different NPs has shown excellent virucidal properties against various plant viruses. Concerns raised about the fate and long-lasting effects of NPs on plants, soil microflora, humans, and the ecosystem. NPs have beneficial as well as harmful impacts on plants and the environment. This review discusses significant studies done to manage plant viral diseases. Silver, gold, zinc, copper, magnesium, nickel, silica, and bio-compounds nanomaterials were applied to control the virus and results have been compiled to draw a picture of the problem. This discussion will address the benefits of nanotechnology in plant viral disease management and the detrimental impacts of nanotechnology on the ecosystem.

Insight into maize gene expression profiles responses to symbiotic bacteria derived from Helicoverpa armigera and Ostrinia furnacalis.

The insects of Ostrinia furnacalis and Helicoverpa armigera are the two main pests that affect maize growth, which significantly decrease the yield. Plants induce various immune-related pathways to antagonize insect feeding during insect-plant interactions. Moreover, different insect elicitors or effectors participate in the interactions via releasing into plants. While there are many bacteria during insect regurgitation, their roles in insect-plant interaction are unknown. In this study, four bacterial strains were isolated from regurgitation fluid of O. furnacalis and H. armigera, and their cultures were inoculated on maize leaves for response analysis. All the four bacterial strains altered gene expression profiles in maize, and these altered expression profiles included phytohormones, secondary metabolic pathways, transcription factors, MAPK, and plant-pathogen interaction-related genes. A total of 210 genes, such as WRKY54, WRKY62, PIF5, argonaute 1, Xa21, NRR, ubiquitin-proteasome system genes, were co-changed in response to bacterial inoculation. These changes were similar with maize gene profile changes after insect feeding. Symbiotic insect bacteria participate in insect-plant interactions by changing maize gene expression profiles, which might be used to develop anti-pest microbial agents by activating plant defense system with identified microbes. In future, understanding the roles of symbiotic insect bacteria on plant-insect interaction might provide a promising and novel strategy for pest biocontrol using microbes.

Characterisation of rice-associated antagonistic pseudomonads and their application in combination with plant resistance inducer molecules for the control of sheath blight disease of rice

ABSTRACT Rice sheath blight caused by Rhizoctonia solani AG1-IA is one of the most important diseases of high-yielding rice (Oryza sativa L.) cultivars in rice-growing areas of the world including Iran. This study aimed to determine the efficacy of native fluorescent pseudomonads in combination with plant defence activators in controlling rice sheath blight disease. Sampling was done from local and high-yielding rice cultivars grown in Mazandaran province, Iran. A total of 291 fluorescent strains were isolated and screened for antagonism against R. solani. The isolates Ps-275, Ps-128, Ps-287, Ps-240 and Ps-243 reduced the disease symptoms up to 53.1­%, 49.3%, 44.76%, 40.83% and 35.7­%, respectively, only when applied in combination with potassium silicate at the booting stage of rice growth. The isolate Ps-3 reduced the disease symptoms when applied alone and in combination with oxalic acid by 60.5% and 58.7%, respectively. Multilocus sequence analysis of house-keeping genes, rpoD, oprI and oprL identified the most effective antagonistic isolates, Ps-275, Ps-3 and Ps-287, as endemic Pseudomonas strains affiliated with the P. protegens, P. mosselii and P. aeruginosa (sub) groups, respectively. These strains significantly inhibited the growth of R. solani AG1-IA in vitro and reduced the disease symptoms at the booting stage of the rice plant as well.

Defence-related pathways, phytohormones and primary metabolism are key players in kiwifruit plant tolerance to Pseudomonas syringae pv. actinidiae.

The reasons underlying the differential tolerance of Actinidia spp. to the pandemic pathogen Pseudomonas syringae pv. actinidiae (Psa) have not yet been elucidated. We hypothesized that differential plant-defence strategies linked to transcriptome regulation, phytohormonesand primary metabolism might be key and that Actinidiachinensis susceptibility results from an inefficient activation of defensive mechanisms and metabolic impairments shortly following infection. Here, 48 h postinoculation bacterial density was 10-fold higher in A. chinensis var. deliciosa than in Actinidiaarguta, accompanied by significant increases in glutamine, ornithine, jasmonic acid (JA) and salicylic acid (SA) (up to 3.2-fold). Actinidiaarguta showed decreased abscisic acid (ABA) (0.7-fold), no changes in primary metabolites, and 20 defence-related genes that were only differentially expressed in this species. These include GLOX1, FOX1, SN2 and RBOHA, which may contribute to its higher tolerance. Results suggest that A. chinensis' higher susceptibility to Psa is due to an inefficient activation of plant defences, with the involvement of ABA, JA and SA, leading to impairments in primary metabolism, particularly the ammonia assimilation cycle. A schematic overview on the interaction between Psa and genotypes with distinct tolerance is provided, highlighting the key transcriptomic and metabolomic aspects contributing to the different plant phenotypes after infection.

Root treatment with a vitamin K3 derivative: a promising alternative to synthetic fungicides against Botrytis cinerea in tomato plants.

Botrytis cinerea, the causal agent of gray mold has a great economic impact on several important crops. This necrotrophic fungus causes disease symptoms during vegetative growth and also into postharvest stages. The current method to combat this disease is fungicide application, with high economic costs and environmentally unsustainable impacts. Moreover, there is an increasing general public health concern about these strategies of crop protection. We studied the protection of tomato plants against B. cinerea by previous root treatment with menadione sodium bisulfite (MSB), a known plant defense activator. Root treatment 48 h before inoculation with MSB 0.6 mmol L-1 reduced leaf lesion diameter by 30% and notably cell deaths, compared to control plants 72 h after inoculation. We studied the expression level of several pathogenesis-related (PR) genes from different defense transduction pathways, and found that MSB primes higher PR1 expression against B. cinerea. However, this stronger induced resistance was impaired in transgenic salicylic acid-deficient NahG line. Additionally, in the absence of pathogen challenge, MSB increased tomato plant growth by 28% after 10 days. Our data provide evidence that MSB protects tomato plants against B. cinerea by priming defense responses through the salicylic acid (SA)-dependent signaling pathway and reducing oxidative stress. This work confirms the efficacy of MSB as plant defense activator against B. cinerea and presents a novel alternative to combat gray mold in important crops.

On the issue of protection of yellow lupine from anthracnose in the field

AnnotationOver the years of many years of research in the field, it was found that the creation of completely anthracnose-resistant varieties of yellow lupine (Lupinus Luteus L) is not possible. But at each stage of the pathological process, various defense mechanisms operate that determine the resistance or susceptibility of plants to diseases. There is a passive defense associated with morpho-biological features. A positive role in the control of anthracnose of early and mid-season forms with limited second-order shoots, fast-growing ones with anthocyanin coloration, xeromorphic leaf type, dark green color of vegetative organs, intensely colored seeds (2c, 4c, 2d), different corolla colors (numbers 52-87-2113 and 1477-1-17) and a flower (varieties Iputsky and Rodnik). Observations have shown that a waxy coating on a bean or a thick layer of hairs that helps water roll off, a more spreading bush that provides quick ventilation and moisture removal, reduces anthracnose infestation. It was found that the passive defense mechanism is largely due to the totality of morpho-biological characteristics and the nature of their interaction. Different infestation with anthracnose depending on the sowing density was shown: under conditions of sparse sowing (600 thousand seeds / ha), it averaged 4.6% during flowering and 8.0% at bean formation, and in a denser cenosis (1.2 mln. grain / ha), respectively, 18.7 and 62.0%. An active plant defense mechanism has been established and is being studied -hypersensitivity - this is an increased sensitivity of living cells of a plant - a host in places where a pathogen penetrates and its rapid death with the formation of necrosis. It was revealed that necrotic forms of yellow lupine are less affected by anthracnose during all phases of plant growth and development and, especially, during the formation of beans. At the site of penetration of the pathogen, an orange spot develops, around which a roller of dead tissue is formed, i.e., the pathogen’s access to living cells stops at the expense of which it feeds. The selected material with bean necrosis, without external sporulation, reduces the infectious load in the infected crops.

Different epitopes of Ralstonia solanacearum effector RipAW are recognized by two Nicotiana species and trigger immune responses.

Diverse pathogen effectors convergently target conserved components in plant immunity guarded by intracellular nucleotide‐binding domain leucine‐rich repeat receptors (NLRs) and activate effector‐triggered immunity (ETI), often causing cell death. Little is known of the differences underlying ETI in different plants triggered by the same effector. In this study, we demonstrated that effector RipAW triggers ETI on Nicotiana benthamiana and Nicotiana tabacum. Both the first 107 amino acids (N1‐107) and RipAW E3‐ligase activity are required but not sufficient for triggering ETI on N. benthamiana. However, on N. tabacum, the N1‐107 fragment is essential and sufficient for inducing cell death. The first 60 amino acids of the protein are not essential for RipAW‐triggered cell death on either N. benthamiana or N. tabacum. Furthermore, simultaneous mutation of both R75 and R78 disrupts RipAW‐triggered ETI on N. tabacum, but not on N. benthamiana. In addition, N. tabacum recognizes more RipAW orthologs than N. benthamiana. These data showcase the commonalities and specificities of RipAW‐activated ETI in two evolutionally related species, suggesting Nicotiana species have acquired different abilities to perceive RipAW and activate plant defences during plant–pathogen co‐evolution.