Genetic structure and population diversity of Phytophthora infestans strains in Pacific western Canada.

Late blight caused by Phytophthora infestans is an economically important disease of potato and tomato worldwide. In Canada, an increase in late blight incidence and severity coincided with changes in genetic composition of P. infestans. We monitored late blight incidence on tomato and potato in Pacific western and eastern Canada between 2019 and 2022, identified genotypes of P. infestans, and examined their population genetic diversity. We identified four major existing genotypes US11, US17, US8, and US23 as well as 25 new genotypes. The US11 genotype was dominant in Pacific western Canada, accounting for 59% of the total population. We discovered the US17 genotype for the first time in Canada. We revealed a higher incidence of late blight and quite diverse genotypes of P. infestans in Pacific western Canada than in eastern Canada. We found high genetic diversity of P. infestans population from Pacific western Canada, as evidenced by the high number of multilocus genotypes, high values of genetic diversity indices, and emergence of 25 new genotypes. Considering the number of disease incidence, the detection of diverse known genotypes, the emergence of novel genotypes, and the high number of isolates resistant to metalaxyl-m (95%) from Pacific western Canada, the region could play a role in establishing sexual recombination and diverse populations, which could ultimately pose challenges for late blight management. Therefore, continuous monitoring of P. infestans populations in Pacific western region and across Canada is warranted. KEY POINTS: • Genotypes of P. infestans in Pacific western were quite diverse than in eastern Canada. • We discovered US17 genotype for the first time in Canada and identified 26 novel genotypes. • Approximately 95% of P. infestans isolates were resistant to metalaxyl-m.

Anti-Oomycete Effect and Mechanism of Salicylic Acid on Phytophthora infestans.

Pathogenic oomycetes infect a wide variety of organisms, including plants, animals, and humans, and cause massive economic losses in global agriculture, aquaculture, and human health. Salicylic acid (SA), an endogenous phytohormone, is regarded as an inducer of plant immunity. Here, the potato late blight pathogen Phytophthora infestans was used as a model system to uncover the inhibitory mechanisms of SA on pathogenic oomycetes. In this research, SA significantly inhibited the mycelial growth, sporulation, sporangium germination, and virulence of P. infestans. Inhibition was closely related to enhanced autophagy, suppression of translation initiation, and ribosomal biogenesis in P. infestans, as shown by multiomics analysis (transcriptomics, proteomics, and phosphorylated proteomics). Monodansylcadaverine (MDC) staining and Western blotting analysis showed that SA promoted autophagy in P. infestans by probably targeting the TOR signaling pathway. These observations suggest that SA has the potential to control late blight caused by P. infestans.

Effectiveness of potato late blight (Phytophthora infestans) forecast by meteorological estimation in mountainous terrain based on CARAH rules.

Potato late blight (PLB) caused by Phytophthora infestans (Mont.) de Bary, its incidence and development are highly dependent on meteorological conditions. To solve the problem of PLB in mountainous terrain under the condition of limited meteorological monitoring capability, the air temperature and humidity was estimated based on the basic meteorological datasets, the forecast effect of the onset period and infection cycle of PLB based on CARAH rules was evaluated. The average MAE, RMSE and CI of the estimated air temperature and observations were 1.17 °C, 1.52 °C and 0.95, respectively. The average MAE, RMSE and CI of the estimated relative humidity and observations were 8.0 %, 10.7 % and 0.53, respectively. The curve of the infection cycle of PLB at different locations were estimated from the basic meteorological datasets based on the CARAH rules, and the false alarm and missing ratios were 8.8 % and 4.6 % respectively. It may be delayed by 1 or 2 fungal generations compared to the observations, and then the protective fungicide should be adjusted to a systemic fungicide. The false alarm of the infection cycle of PLB may increase in dry air conditions, and the missing report may occur in humid condition.

Harnessing Plant's Arsenal: Essential Oils as Promising Tools for Sustainable Management of Potato Late Blight Disease Caused by Phytophthora infestans-A Comprehensive Review.

Potato late blight disease is caused by the oomycete Phytophthora infestans and is listed as one of the most severe phytopathologies on Earth. The current environmental issues require new methods of pest management. For that reason, plant secondary metabolites and, in particular, essential oils (EOs) have demonstrated promising potential as pesticide alternatives. This review presents the up-to-date work accomplished using EOs against P. infestans at various experimental scales, from in vitro to in vivo. Additionally, some cellular mechanisms of action on Phytophthora spp., especially towards cell membranes, are also presented for a better understanding of anti-oomycete activities. Finally, some challenges and constraints encountered for the development of EOs-based biopesticides are highlighted.

A review of biocontrol agents in controlling late blight of potatoes and tomatoes caused by Phytophthora infestans and the underlying mechanisms.

Phytophthora infestans causes late blight on potatoes and tomatoes, which has a significant economic impact on agriculture. The management of late blight has been largely dependent on the application of synthetic fungicides, which is not an ultimate solution for sustainable agriculture and environmental safety. Biocontrol strategies are expected to be alternative methods to the conventional chemicals in controlling plant diseases in the integrated pest management (IPM) programs. Well-studied biocontrol agents against Phytophthora infestans include fungi, oomycetes, bacteria, and compounds produced by these antagonists, in addition to certain bioactive metabolites produced by plants. Laboratory and glasshouse experiments suggest a potential for using biocontrol in practical late blight disease management. However, the transition of biocontrol to field applications is problematic for the moment, due to low and variable efficacies. In this review, we provide a comprehensive summary on these biocontrol strategies and the underlying corresponding mechanisms. To give a more intuitive understanding of the promising biocontrol agents against Phytophthora infestans in agricultural systems, we discuss the utilizations, modes of action and future potentials of these antagonists based on their taxonomic classifications. To achieve a goal of best possible results produced by biocontrol agents, it is suggested to work on field trials, strain modifications, formulations, regulations, and optimizations of application. Combined biocontrol agents having different modes of action or biological adaptation traits may be used to strengthen the biocontrol efficacy. More importantly, biological control agents should be applied in the coordination of other existing and forthcoming methods in the IPM programs. © 2023 Society of Chemical Industry.

Endophytic Bacillus subtilis H17-16 effectively inhibits Phytophthora infestans, the pathogen of potato late blight, and its potential application.

BACKGROUND: As a highly prevalent epidemic disease of potato, late blight caused by Phytophthora infestans poses a serious threat to potato yield and quality. At present, chemical fungicides are mainly used to control potato late blight, but long-term overuse of chemical fungicides may lead to environmental pollution and human health threats. Endophytes, natural resources for plant diseases control, can promote plant growth, enhance plant resistance, and secrete antifungal substances. Therefore, there is an urgent need to find some beneficial endophytes to control potato late blight. RESULTS: We isolated a strain of Bacillus subtilis H17-16 from potato healthy roots. It can significantly inhibit mycelial growth, sporangia germination and the pathogenicity of Phytophthora infestans, induce the resistance of potato to late blight, and promote potato growth. In addition, H17-16 has the ability to produce protease, volatile compounds (VOCs) and form biofilms. After H17-16 treatment, most of the genes involved in metabolism, virulence and drug resistance of Phytophthora infestans were down-regulated significantly, and the genes related to ribosome biogenesis were mainly up-regulated. Moreover, field and postharvest application of H17-16 can effectively reduce the occurrence of potato late blight, and the combination of H17-16 with chitosan or chemical fungicides had a better effect than single H17-16. CONCLUSION: Our results reveal that Bacillus subtilis H17-16 has great potential as a natural fungicide for controlling potato late blight, laying a theoretical basis for its development as a biological control agent. © 2023 Society of Chemical Industry.

Comparative transcriptome profiling of potato cultivars infected by late blight pathogen Phytophthora infestans: Diversity of quantitative and qualitative responses.

The Estonia potato cultivar Ando has shown elevated field resistance to Phytophthora infestans, even after being widely grown for over 40 years. A comprehensive transcriptional analysis was performed using RNA-seq from plant leaf tissues to gain insight into the mechanisms activated for the defense after infection. Pathogen infection in Ando resulted in about 5927 differentially expressed genes (DEGs) compared to 1161 DEGs in the susceptible cultivar Arielle. The expression levels of genes related to plant disease resistance such as serine/threonine kinase activity, signal transduction, plant-pathogen interaction, endocytosis, autophagy, mitogen-activated protein kinase (MAPK), and others were significantly enriched in the upregulated DEGs in Ando, whereas in the susceptible cultivar, only the pathway related to phenylpropanoid biosynthesis was enriched in the upregulated DEGs. However, in response to infection, photosynthesis was deregulated in Ando. Multi-signaling pathways of the salicylic-jasmonic-ethylene biosynthesis pathway were also activated in response to Phytophthora infestans infection.

Transcriptome-Assisted SNP Marker Discovery for Phytophthora infestans Resistance in Solanum lycopersicum L.

Late blight, caused by oomycetes Phytophthora infestans is one of the most challenging fungal diseases to manage in tomato plants (Solanum lycopersicum L.). Toward managing the disease, conventional breeding has successfully introgressed genetic loci conferring disease resistance from various wild relatives of tomato into commercial varieties. The cataloging of disease-associated SNP markers and a deeper understanding of disease-resistance mechanisms are needed to keep up with the demand for commercial varieties resistant against emerging pathogen strains. To this end, we performed transcriptome sequencing to evaluate the gene expression dynamics of tomato varieties, resistant and susceptible to Phytophthora infection. Further integrating the transcriptome dataset with large-scale public genomic data of varieties with known disease phenotypes, a panel of single nucleotide polymorphism (SNP) markers correlated with disease resistance was identified. These SNPs were then validated on 31 lines with contrasting phenotypes for late blight. The identified SNPs are located on genes coding for a putative cysteine-rich transmembrane module (CYSTM), Solyc09g098310, and a nucleotide-binding site-leucine-rich repeat protein, Solyc09g098100, close to the well-studied Ph-3 resistance locus known to have a role in plant immunity against fungal infections. The panel of SNPs generated by this study using transcriptome sequencing showing correlation with disease resistance across a broad set of plant material can be used as markers for molecular screening in tomato breeding.

Characterization of host-effector transcription dynamics during pathogen infection in engineered late blight resistant potato.

Phytophthora infestans, the etiologic agent of late blight, is a threat to potato production in areas with high humidity during the growing season. The oomycete pathogen is hemi-biotrophic, it establishes infection on living plant cells and then spreads, kills, and feeds off the necrotized plant tissue material. The interaction between host and pathogen is complex with dynamic pathogen RXLR effectors and potato NB-LRR resistance proteins actively competing for dominance and survival. Late blight protection was brought to several cultivars of potato through insertion of the wild potato (Solanum venturii) NB-LRR resistance gene Rpi-vnt1.1. We have established that the late blight protection trait, mediated by Rpi-vnt1.1, is effective despite low expression of RNA. The RNA expression dynamics of Rpi-vnt1.1 and the cognate pathogen RXLR effector, Avr-vnt1, were evaluated following spray inoculation with up to five different contemporary late blight isolates from North America and South America. Following inoculations, RXLR effector transcript profiles provided insight into interaction compatibility in relation to markers of the late blight hemi-biotrophic lifecycle.

Portable Diffuse Reflectance Spectroscopy of Potato Leaves for Pre-Symptomatic Detection of Late Blight Disease.

We report on the use of leaf diffuse reflectance spectroscopy for plant disease detection. A smartphone-operated, compact diffused reflectance spectrophotometer is used for field collection of leaf diffuse reflectance spectra to enable pre-symptomatic detection of the progression of potato late blight disease post inoculation with oomycete pathogen Phytophthora infestans. Neural-network-based analysis predicts infection with >96% accuracy, only 24 h after inoculation with the pathogen, and nine days before visual late blight symptoms appear. Our study demonstrates the potential of using portable optical spectroscopy in tandem with machine learning analysis for early diagnosis of plant diseases.

Nucleotide-binding leucine-rich repeat network underlies nonhost resistance of pepper against the Irish potato famine pathogen Phytophthora infestans.

Nonhost resistance (NHR) is a robust plant immune response against non-adapted pathogens. A number of nucleotide-binding leucine-rich repeat (NLR) proteins that recognize non-adapted pathogens have been identified, although the underlying molecular mechanisms driving robustness of NHR are still unknown. Here, we screened 57 effectors of the potato late blight pathogen Phytophthora infestans in nonhost pepper (Capsicum annuum) to identify avirulence effector candidates. Selected effectors were tested against 436 genome-wide cloned pepper NLRs, and we identified multiple functional NLRs that recognize P. infestans effectors and confer disease resistance in the Nicotiana benthamiana as a surrogate system. The identified NLRs were homologous to known NLRs derived from wild potatoes that recognize P. infestans effectors such as Avr2, Avrblb1, Avrblb2, and Avrvnt1. The identified CaRpi-blb2 is a homologue of Rpi-blb2, recognizes Avrblb2 family effectors, exhibits feature of lineage-specifically evolved gene in microsynteny and phylogenetic analyses, and requires pepper-specific NRC (NLR required for cell death)-type helper NLR for proper function. Moreover, CaRpi-blb2-mediated hypersensitive response and blight resistance were more tolerant to suppression by the PITG_15 278 than those mediated by Rpi-blb2. Combined results indicate that pepper has stacked multiple NLRs recognizing effectors of non-adapted P. infestans, and these NLRs could be more tolerant to pathogen-mediated immune suppression than NLRs derived from the host plants. Our study suggests that NLRs derived from nonhost plants have potential as untapped resources to develop crops with durable resistance against fast-evolving pathogens by stacking the network of nonhost NLRs into susceptible host plants.

A Phytophthora infestans RXLR effector targets a potato ubiquitin-like domain-containing protein to inhibit the proteasome activity and hamper plant immunity.

Ubiquitin-like domain-containing proteins (UDPs) are involved in the ubiquitin-proteasome system because of their ability to interact with the 26S proteasome. Here, we identified potato StUDP as a target of the Phytophthora infestans RXLR effector Pi06432 (PITG_06432), which supresses the salicylic acid (SA)-related immune pathway. By overexpressing and silencing of StUDP in potato, we show that StUDP negatively regulates plant immunity against P. infestans. StUDP interacts with, and destabilizes, the 26S proteasome subunit that is referred to as REGULATORY PARTICLE TRIPLE-A ATP-ASE (RPT) subunit StRPT3b. This destabilization represses the proteasome activity. Proteomic analysis and Western blotting show that StUDP decreases the stability of the master transcription factor SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) in SA biosynthesis. StUDP negatively regulates the SA signalling pathway by repressing the proteasome activity and destabilizing StSARD1, leading to a decreased expression of the SARD1-targeted gene ISOCHORISMATE SYNTHASE 1 and thereby a decrease in SA content. Pi06432 stabilizes StUDP, and it depends on StUDP to destabilize StRPT3b and thereby supress the proteasome activity. Our study reveals that the P. infestans effector Pi06432 targets StUDP to hamper the homeostasis of the proteasome by the degradation of the proteasome subunit StRPT3b and thereby suppresses SA-related immunity.

Dissection of the Plant Hormone Signal Transduction Network in Late Blight-Resistant Potato Genotype SD20 and Prediction of Key Resistance Genes.

Hormones play an important role in plant disease resistance and defense. Transcriptome data of late blight-resistant potato genotype SD20 treated by ethylene (ET), jasmonate (JA), salicylic acid (SA), and Phytophthora infestans CN152 was analyzed to assess the role of the ET/JA/SA regulatory network in plant disease resistance and defense and predict key resistant genes. The results show that there was significant crossover of differentially expressed genes among all treatments, and common and specific plant disease interaction genes for the ET, JA, and SA treatments were differentially expressed in the CN152 treatment. The resistance and defense genes of the potato genotype SD20 could be induced to regulate metabolic and hormone signaling pathways by alternative splicing in all treatments. Further analysis found that JA and ET pathways can work together synergistically. JA/ET and SA pathways antagonize each other to initiate the expression of calmodulin-domain protein kinases and calmodulin/calmodulin-like and RPM1-interacting protein 4 genes, and they activate HSP-mediated hypersensitive response and defense-related genes. Meanwhile, nine defense genes, including wound-responsive AP2-like factor, glutathione-s-transferase, serine/threonine-protein kinase BRI1, and Avr9/Cf-9 rapidly elicited protein genes, were obtained using weighted gene coexpression network analysis, which provided reliable targets for functional verification. This study provides a theoretical reference for the comprehensive application of plant hormones to improve resistance to potato late blight disease.

Early detection of late blight in potato by whole-plant redox imaging.

Late blight caused by the oomycete Phytophthora infestans is a most devastating disease of potatoes (Solanum tuberosum). Its early detection is crucial for suppressing disease spread. Necrotic lesions are normally seen in leaves at 4 days post-inoculation (dpi) when colonized cells are dead, but early detection of the initial biotrophic growth stage, when the pathogen feeds on living cells, is challenging. Here, the biotrophic growth phase of P. infestans was detected by whole-plant redox imaging of potato plants expressing chloroplast-targeted reduction-oxidation sensitive green fluorescent protein (chl-roGFP2). Clear spots on potato leaves with a lower chl-roGFP2 oxidation state were detected as early as 2 dpi, before any visual symptoms were recorded. These spots were particularly evident during light-to-dark transitions, and reflected the mislocalization of chl-roGFP2 outside the chloroplasts. Image analysis based on machine learning enabled systematic identification and quantification of spots, and unbiased classification of infected and uninfected leaves in inoculated plants. Comparing redox with chlorophyll fluorescence imaging showed that infected leaf areas that exhibit mislocalized chl-roGFP2 also showed reduced non-photochemical quenching and enhanced quantum PSII yield (ΦPSII) compared with the surrounding leaf areas. The data suggest that mislocalization of chloroplast-targeted proteins is an efficient marker of late blight infection, and demonstrate how it can be utilized for non-destructive monitoring of the disease biotrophic stage using whole-plant redox imaging.

Complete Genome Sequence Data of Novel Streptomyces angustmyceticus Strain CQUSa03, a Potential Biological Control Agent for Potato Oomycete and Fungal Diseases.

Streptomyces angustmyceticus CQUSa03 was recently isolated from the rhizosphere soil of a potato resistant variety, which showed strong biocontrol activity against potato late blight and other fungal diseases. To elucidate the biocontrol mechanism, the whole genome of CQUSa03 was sequenced using second-generation Illumina and third-generation Nanopore sequencing technologies. The assembled genome of CQUSa03 was 8,107,672 bp, containing one chromosome and three plasmids, with an average GC content of 72.29%, 6,914 protein-coding genes, 21 rRNA, and 68 tRNA. In addition, 29 important secondary metabolite biosynthetic gene clusters were identified in the CQUSa03 genome. The related genes of ß-1,3-glucanase and chitinase, which can degrade the cell wall of fungal pathogens, were also found. CQUSa03 is predicted to have great potential in agriculture by producing a variety of antagonistic active compounds, cell wall hydrolases, and bacteriostatic peptides to control diseases. The genome sequence provided a theoretical basis for analyzing the biocontrol mechanism of S. angustmyceticus CQUSa03 and laid a foundation for the development and industrialization of biocontrol agents.

Genetically modified (GM) late blight-resistant potato and consumer attitudes before and after a field visit.

Late blight, caused by Phytophthora infestans, is the most devastating disease in potato production. Here, we show full late blight resistance in a location with a genetically diverse pathogen population with the use of GM potato stacked with three resistance (R) genes over three seasons. In addition, using this field trials, we demonstrate that in-the-field intervention among consumers led to change for more favorable attitude generally toward GM crops.

A potato late blight resistance gene protects against multiple Phytophthora species by recognizing a broadly conserved RXLR-WY effector.

Species of the genus Phytophthora, the plant killer, cause disease and reduce yields in many crop plants. Although many Resistance to Phytophthora infestans (Rpi) genes effective against potato late blight have been cloned, few have been cloned against other Phytophthora species. Most Rpi genes encode nucleotide-binding domain, leucine-rich repeat-containing (NLR) immune receptor proteins that recognize RXLR (Arg-X-Leu-Arg) effectors. However, whether NLR proteins can recognize RXLR effectors from multiple Phytophthora species has rarely been investigated. Here, we identified a new RXLR-WY effector AVRamr3 from P. infestans that is recognized by Rpi-amr3 from a wild Solanaceae species Solanum americanum. Rpi-amr3 associates with AVRamr3 in planta. AVRamr3 is broadly conserved in many different Phytophthora species, and the recognition of AVRamr3 homologs by Rpi-amr3 activates resistance against multiple Phytophthora pathogens, including the tobacco black shank disease and cacao black pod disease pathogens P. parasitica and P. palmivora. Rpi-amr3 is thus the first characterized resistance gene that acts against P. parasitica or P. palmivora. These findings suggest a novel path to redeploy known R genes against different important plant pathogens.

A Phytophthora effector promotes homodimerization of host transcription factor StKNOX3 to enhance susceptibility.

Oomycete pathogens secrete hundreds of cytoplasmic RxLR effectors to modulate host immunity by targeting diverse plant proteins. Revealing how effectors manipulate host proteins is pivotal to understanding infection processes and to developing new strategies to control plant disease. Here we show that the Phytophthora infestans RxLR effector Pi22798 interacts in the nucleus with a potato class II knotted-like homeobox (KNOX) transcription factor, StKNOX3. Silencing the ortholog NbKNOX3 in Nicotiana benthamiana reduces host colonization by P. infestans, whereas transient and stable overexpression of StKNOX3 enhances infection. StKNOX3 forms a homodimer which is dependent on its KNOX II domain. The KNOX II domain is also essential for Pi22798 interaction and for StKNOX3 to enhance P. infestans colonization, indicating that StKNOX3 homodimerization contributes to susceptibility. However, critically, the effector Pi22798 promotes StKNOX3 homodimerization, rather than heterodimerization to another KNOX transcription factor StKNOX7. These results demonstrate that the oomycete effector Pi22798 increases pathogenicity by promoting homodimerization specifically of StKNOX3 to enhance susceptibility.

Disease Inhibiting Effect of Strain Bacillus subtilis EG21 and Its Metabolites Against Potato Pathogens Phytophthora infestans and Rhizoctonia solani.

Potato production worldwide is plagued by several disease-causing pathogens that result in crop and economic losses estimated to billions of dollars each year. To this day, synthetic chemical applications remain the most widespread control strategy despite their negative effects on human and environmental health. Therefore, obtainment of superior biocontrol agents or their naturally produced metabolites to replace fungicides or to be integrated into practical pest management strategies has become one of the main targets in modern agriculture. Our main focus in the present study was to elucidate the antagonistic potential of a new strain identified as Bacillus subtilis EG21 against potato pathogens Phytophthora infestans and Rhizoctonia solani using several in vitro screening assays. Microscopic examination of the interaction between EG21 and R. solani showed extended damage in fungal mycelium, while EG21 metabolites displayed strong anti-oomycete and zoosporecidal effect on P. infestans. Mass spectrometry (MS) analysis revealed that EG21 produced antifungal and anti-oomycete cyclic lipopeptides surfactins (C12 to C19). Further characterization of EG21 confirmed its ability to produce siderophores and the extracellular lytic enzymes cellulase, pectinase and chitinase. The antifungal activity of EG21 cell-free culture filtrate (CF) was found to be stable at high-temperature/pressure treatment and extreme pH values and was not affected by proteinase K treatment. Disease-inhibiting effect of EG21 CF against P. infestans and R. solani infection was confirmed using potato leaves and tubers, respectively. Biotechnological applications of using microbial agents and their bioproducts for crop protection hold great promise to develop into effective, environment-friendly and sustainable biocontrol strategies. [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.

Nitric Oxide Implication in Potato Immunity to Phytophthora infestans via Modifications of Histone H3/H4 Methylation Patterns on Defense Genes.

Nitric oxide (NO) is an essential redox-signaling molecule operating in many physiological and pathophysiological processes. However, evidence on putative NO engagement in plant immunity by affecting defense gene expressions, including histone modifications, is poorly recognized. Exploring the effect of biphasic NO generation regulated by S-nitrosoglutathione reductase (GNSOR) activity after avr Phytophthora infestans inoculation, we showed that the phase of NO decline at 6 h post-inoculation (hpi) was correlated with the rise of defense gene expressions enriched in the TrxG-mediated H3K4me3 active mark in their promoter regions. Here, we report that arginine methyltransferase PRMT5 catalyzing histone H4R3 symmetric dimethylation (H4R3sme2) is necessary to ensure potato resistance to avr P. infestans. Both the pathogen and S-nitrosoglutathione (GSNO) altered the methylation status of H4R3sme2 by transient reduction in the repressive mark in the promoter of defense genes, R3a and HSR203J (a resistance marker), thereby elevating their transcription. In turn, the PRMT5-selective inhibitor repressed R3a expression and attenuated the hypersensitive response to the pathogen. In conclusion, we postulate that lowering the NO level (at 6 hpi) might be decisive for facilitating the pathogen-induced upregulation of stress genes via histone lysine methylation and PRMT5 controlling potato immunity to late blight.