Structural and Phylogenetic In Silico Characterization of Vitis vinifera PRR Protein as Potential Target for Plasmopara viticola Infection.

Fungi infection, especially derived from Plasmopara viticola, causes severe grapevine economic losses worldwide. Despite the availability of chemical treatments, looking for eco-friendly ways to control Vitis vinifera infection is gaining much more attention. When a plant is infected, multiple disease-control molecular mechanisms are activated. PRRs (Pattern Recognition Receptors) and particularly RLKs (receptor-like kinases) take part in the first barrier of the immune system, and, as a consequence, the kinase signaling cascade is activated, resulting in an immune response. In this context, discovering new lectin-RLK (LecRLK) membrane-bounded proteins has emerged as a promising strategy. The genome-wide localization of potential LecRLKs involved in disease defense was reported in two grapevine varieties of great economic impact: Chardonnay and Pinot Noir. A total of 23 potential amino acid sequences were identified, exhibiting high-sequence homology and evolution related to tandem events. Based on the domain architecture, a carbohydrate specificity ligand assay was conducted with docking, revealing two sequences as candidates for specific Vitis vinifera-Plasmopara viticola host-pathogen interaction. This study confers a starting point for designing new effective antifungal treatments directed at LecRLK targets in Vitis vinifera.

Activity of OSBPI fungicide fluoxapiprolin against plant-pathogenic oomycetes and its systemic translocation in plants.

Fluoxapiprolin, a novel piperidinyl thiazole isoxazoline fungicide, was developed by Bayer Crop Science in 2012. Despite its well-documented inhibitory activity against plant pathogenic oomycetes such as Phytophthora capsici and Phytophthora infestans, limited information regarding its antifungal spectrum and protective and curative activity is available. Fluoxapiprolin exhibited strong inhibitory activity against Phytophthora spp. and several Pythium spp., with EC50 values ranging from 2.12 × 10-4 to 2.92 µg/mL. It was much more effective against P. capsici in inhibiting mycelial growth, sporangium production, and cystospore germination than at reducing zoospore release. Moreover, fluoxapiprolin displayed both protective and curative activity against P. capsici infection in pepper plants under greenhouse conditions, with systemic translocation capability confirmed by High Performance Liquid Chromatography (HPLC) analysis. The results demonstrated the strong inhibitory activity of fluoxapiprolin against economically important plant oomycete pathogens, including Phytophthora spp. and several Pythium spp., and its certain translocation activity in pepper plants.

Plasmopara viticola effector PvCRN20 represses the import of VvDEG5 into chloroplasts to suppress immunity in grapevine.

Chloroplasts play a crucial role in plant defense against pathogens, making them primary targets for pathogen effectors that suppress host immunity. This study characterizes the Plasmopara viticola CRN-like effector, PvCRN20, which interacts with DEG5 in the cytoplasm but not with its interacting protein, DEG8, which is located in the chloroplast. By transiently overexpressing in tobacco leaves, we show that PvCRN20 could inhibit INF1- and Bax-triggered cell death. Constitutive expression of PvCRN20 suppresses the accumulation of reactive oxygen species (ROS) and promotes pathogen colonization. PvCRN20 reduces DEG5 entry into chloroplasts, thereby disrupting DEG5 and DEG8 interactions in chloroplasts. Overexpression of VvDEG5 and VvDEG8 induces ROS accumulation and enhances grapevine resistance to P. viticola, whereas knockout of VvDEG8 represses ROS production and promotes P. viticola colonization. Consistently, ectopic expression of VvDEG5 and VvDEG8 in tobacco promotes chloroplast-derived ROS accumulation, whereas co-expression of PvCRN20 counteracted this promotion by VvDEG5. Therefore, DEG5 is essential for the virulence function of PvCRN20. Although PvCRN20 is located in both the nucleus and cytoplasm, only cytoplasmic PvCRN20 suppresses plant immunity and promotes pathogen infection. Our results reveal that PvCRN20 dampens plant defenses by repressing the chloroplast import of DEG5, thus reducing host ROS accumulation and facilitating pathogen colonization.

ADP-ribosylation factor 1 (ARF1) protein interacts with elicitor PvNLP7 from Plasmopara viticola to mediate PvNLP7-triggered immunity.

Revealing the effector-host molecular interactions is crucial for understanding the host immunity against Plasmopara viticola and devising innovative disease management strategies. As a pathogenic oomycete causing grapevine downy mildew, Plasmopara viticola employs various effectors to manipulate the defense systems of host plants. One of these P. viticola derived effectors is necrosis- and ethylene-inducing peptide 1 (Nep1) -like protein (PvNLP7), which has been known to elicit cell death and immune responses in plants. However, the underlying molecular mechanisms remain obscure, prompting the focus of this study. Through yeast two-hybrid screening, we have identified the Vitis rotundifolia ADP-ribosylation factor (VrARF1) as a host interactor of PvNLP7. This interaction is corroborated through bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) assays. Heterologous expression of VrARF1 in Nicotiana benthamiana verifies its accumulation in both the cytoplasm and nucleus, and induction of cell death. Moreover, the VrARF1 gene is strongly induced during early P. viticola infection and upon PvNLP7 transient expression. Overexpression of the VrARF1 gene in grapevine and N. benthamiana enhances resistance to P. viticola and Phytophthora capsici, respectively, via induction of defense related genes PR1 and PR2. Conversely, virus-induced gene silencing (VIGS) of NbARF1 in N. benthamiana, homologous to VrARF1, markedly attenuates PvNLP7-triggered cell death and reduces the expression of four PTI marker genes (PTI5, Acre31, WRKY7 and Cyp71D20) and two defense related genes (PR1 and PR2), rendering plants transiently transformed with PvNLP7 more susceptible to oomycete P. capsici. These findings highlight the role of ARF1 in mediating PvNLP7-induced immunity and indicate its potential as a target for engineering disease-resistant transgenic plants against oomycete pathogens.

Discovery of Novel Oxathiapiprolin Derivatives as Potent Fungicide Candidates.

Oxathiapiprolin (OXA), which targets the oxysterol-binding protein (OSBP), is an outstanding piperidinyl thiazole isoxazoline (PTI) fungicide that can be used to control oomycetes diseases. In this study, starting from the structure of OXA, a series of novel OSBP inhibitors were designed and synthesized by introducing an indole moiety to replace the pyrazole in OXA. Finally, compound b24 was found to exhibit the highest control effect (82%) against cucumber downy mildew (CDM) in the greenhouse at a very low dosage of 0.069 mg/L, which was comparable to that of OXA (88%). Furthermore, it showed better activity against potato late blight (PLB) than other derivatives of indole. The computational results showed that the R-conformation of b24 should be the dominant conformation binding to PcOSBP. The results of the present work indicate that the 3-fluorine-indole ring is a favorable fragment to increasing the electronic energy when binding with PcOSBP. Furthermore, compound b24 could be used as a lead compound for the discovery of new OSBP inhibitors.

Paths of Least Resistance: Unconventional Effector Secretion by Fungal and Oomycete Plant Pathogens.

Effector secretion by different routes mediates the molecular interplay between host plant and pathogen, but mechanistic details in eukaryotes are sparse. This may limit the discovery of new effectors that could be utilized for improving host plant disease resistance. In fungi and oomycetes, apoplastic effectors are secreted via the conventional endoplasmic reticulum (ER)-Golgi pathway, while cytoplasmic effectors are packaged into vesicles that bypass Golgi in an unconventional protein secretion (UPS) pathway. In Magnaporthe oryzae, the Golgi bypass UPS pathway incorporates components of the exocyst complex and a t-SNARE, presumably to fuse Golgi bypass vesicles to the fungal plasma membrane. Upstream, cytoplasmic effector mRNA translation in M. oryzae requires the efficient decoding of AA-ending codons. This involves the modification of wobble uridines in the anticodon loop of cognate tRNAs and fine-tunes cytoplasmic effector translation and secretion rates to maintain biotrophic interfacial complex integrity and permit host infection. Thus, plant-fungal interface integrity is intimately tied to effector codon usage, which is a surprising constraint on pathogenicity. Here, we discuss these findings within the context of fungal and oomycete effector discovery, delivery, and function in host cells. We show how cracking the codon code for unconventional cytoplasmic effector secretion in M. oryzae has revealed AA-ending codon usage bias in cytoplasmic effector mRNAs across kingdoms, including within the RxLR-dEER motif-encoding sequence of a bona fide Phytophthora infestans cytoplasmic effector, suggesting its subjection to translational speed control. By focusing on recent developments in understanding unconventional effector secretion, we draw attention to this important but understudied area of host-pathogen interactions. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Identification and characterization of specific motifs in effector proteins of plant parasites using MOnSTER.

Plant pathogens cause billions of dollars of crop loss every year and are a major threat to global food security. Identifying and characterizing pathogens effectors is crucial towards their improved control. Because of their poor sequence conservation, effector identification is challenging, and current methods generate too many candidates without indication for prioritizing experimental studies. In most phyla, effectors contain specific sequence motifs which influence their localization and targets in the plant. Therefore, there is an urgent need to develop bioinformatics tools tailored for pathogen effectors. To circumvent these limitations, we have developed MOnSTER a specific tool that identifies clusters of motifs of protein sequences (CLUMPs). MOnSTER can be fed with motifs identified by de novo tools or from databases such as Pfam and InterProScan. The advantage of MOnSTER is the reduction of motif redundancy by clustering them and associating a score. This score encompasses the physicochemical properties of AAs and the motif occurrences. We built up our method to identify discriminant CLUMPs in oomycetes effectors. Consequently, we applied MOnSTER on plant parasitic nematodes and identified six CLUMPs in about 60% of the known nematode candidate parasitism proteins. Furthermore, we found co-occurrences of CLUMPs with protein domains important for invasion and pathogenicity. The potentiality of this tool goes beyond the effector characterization and can be used to easily cluster motifs and calculate the CLUMP-score on any set of protein sequences.

Multiple deletions of candidate effector genes lead to the breakdown of partial grapevine resistance to downy mildew.

Grapevine downy mildew, caused by the oomycete Plasmopara viticola (P. viticola, Berk. & M. A. Curtis; Berl. & De Toni), is a global threat to Eurasian wine grapes Vitis vinifera. Although resistant grapevine varieties are becoming more accessible, P. viticola populations are rapidly evolving to overcome these resistances. We aimed to uncover avirulence genes related to Rpv3.1-mediated grapevine resistance. We sequenced the genomes and characterized the development of 136 P. viticola strains on resistant and sensitive grapevine cultivars. A genome-wide association study was conducted to identify genomic variations associated with resistant-breaking phenotypes. We identified a genomic region associated with the breakdown of Rpv3.1 grapevine resistance (avrRpv3.1 locus). A diploid-aware reassembly of the P. viticola INRA-Pv221 genome revealed structural variations in this locus, including a 30 kbp deletion. Virulent P. viticola strains displayed multiple deletions on both haplotypes at the avrRpv3.1 locus. These deletions involve two paralog genes coding for proteins with 800-900 amino acids and signal peptides. These proteins exhibited a structure featuring LWY-fold structural modules, common among oomycete effectors. When transiently expressed, these proteins induced cell death in grapevines carrying Rpv3.1 resistance, confirming their avirulence nature. This discovery sheds light on the genetic mechanisms enabling P. viticola to adapt to grapevine resistance, laying a foundation for developing strategies to manage this destructive crop pathogen.

A conserved oomycete effector RxLR23 triggers plant defense responses by targeting ERD15La to release NbNAC68.

Oomycete pathogens deliver many effectors to enhance virulence or suppress plant immunity. Plant immune networks are interconnected, in which a few effectors can trigger a strong defense response when recognized by immunity-related proteins. How effectors activate plant defense response remains poorly understood. Here we report Phytophthora capsici effector RxLR23KM can induce plant cell death and plant immunity. RxLR23KM specifically binds to ERD15La, a regulator of abscisic acid and salicylic acid pathway, and the binding intensity depends on the amino acid residues (K93 and M320). NbNAC68, a downstream protein of ERD15La, can stimulate plant immunity that is compromised after binding with ERD15La. Silencing of NbNAC68 substantially prevents the activation of plant defense response. RxLR23KM binds to ERD15La, releasing NbNAC68 to activate plant immunity. These findings highlight a strategy of plant defense response that ERD15La as a central regulator coordinates RxLR23KM to regulate NbNAC68-triggered plant immunity.

Two structurally different oomycete lipophilic microbe-associated molecular patterns induce distinctive plant immune responses.

Plants recognize a variety of external signals and induce appropriate mechanisms to increase their tolerance to biotic and abiotic stresses. Precise recognition of attacking pathogens and induction of effective resistance mechanisms are critical functions for plant survival. Some molecular patterns unique to a certain group of microbes, microbe-associated molecular patterns (MAMPs), are sensed by plant cells as nonself molecules via pattern recognition receptors. While MAMPs of bacterial and fungal origin have been identified, reports on oomycete MAMPs are relatively limited. This study aimed to identify MAMPs from an oomycete pathogen Phytophthora infestans, the causal agent of potato late blight. Using reactive oxygen species (ROS) production and phytoalexin production in potato (Solanum tuberosum) as markers, two structurally different groups of elicitors, namely ceramides and diacylglycerols, were identified. P. infestans ceramides (Pi-Cer A, B, and D) induced ROS production, while diacylglycerol (Pi-DAG A and B), containing eicosapentaenoic acid (EPA) as a substructure, induced phytoalexins production in potato. The molecular patterns in Pi-Cers and Pi-DAGs essential for defense induction were identified as 9-methyl-4,8-sphingadienine (9Me-Spd) and 5,8,11,14-tetraene-type fatty acid (5,8,11,14-TEFA), respectively. These structures are not found in plants, but in oomycetes and fungi, indicating that they are microbe molecular patterns recognized by plants. When Arabidopsis (Arabidopsis thaliana) was treated with Pi-Cer D and EPA, partially overlapping but different sets of genes were induced. Furthermore, expression of some genes is upregulated only after the simultaneous treatment with Pi-Cer D and EPA, indicating that plants combine the signals from simultaneously recognized MAMPs to adapt their defense response to pathogens.

Rapid Detection of Viral, Bacterial, Fungal, and Oomycete Pathogens on Tomatoes with Microneedles, LAMP on a Microfluidic Chip, and Smartphone Device.

Rapid detection of plant diseases before they escalate can improve disease control. Our team has developed rapid nucleic acid extraction methods with microneedles and combined these with loop-mediated amplification (LAMP) assays for pathogen detection in the field. In this work, we developed LAMP assays for early blight (Alternaria linariae, A. alternata, and A. solani) and bacterial spot of tomato (Xanthomonas perforans) and validated these LAMP assays and two previously developed LAMP assays for tomato spotted wilt virus and late blight. Tomato plants were inoculated, and disease severity was measured. Extractions were performed using microneedles, and LAMP assays were run in tubes (with hydroxynaphthol blue) on a heat block or on a newly designed microfluidic slide chip on a heat block or a slide heater. Fluorescence on the microfluidic chip slides was visualized using EvaGreen and photographed on a smartphone. Plants inoculated with X. perforans or tomato spotted wilt virus tested positive prior to visible disease symptoms, whereas Phytophthora infestans and A. linariae were detected at the time of visual disease symptoms. LAMP assays were more sensitive than PCR, and the limit of detection was 1 pg of DNA for both A. linariae and X. perforans. The LAMP assay designed for early blight detected all three species of Alternaria that infect tomato and is thus an Alternaria spp. assay. This study demonstrates the utility of rapid microneedle extraction followed by LAMP on a microfluidic chip for rapid diagnosis of four important tomato pathogens.

Eicosapentaenoic acid: New insights into an oomycete-driven elicitor to enhance grapevine immunity.

The widespread use of pesticides in agriculture remains a matter of major concern, prompting a critical need for alternative and sustainable practices. To address this, the use of lipid-derived molecules as elicitors to induce defence responses in grapevine plants was accessed. A Plasmopara viticola fatty acid (FA), eicosapentaenoic acid (EPA) naturally present in oomycetes, but absent in plants, was applied by foliar spraying to the leaves of the susceptible grapevine cultivar (Vitis vinifera cv. Trincadeira), while a host lipid derived phytohormone, jasmonic acid (JA) was used as a molecule known to trigger host defence. Their potential as defence triggers was assessed by analysing the expression of a set of genes related to grapevine defence and evaluating the FA modulation upon elicitation. JA prompted grapevine immunity, altering lipid metabolism and up-regulating the expression of several defence genes. EPA also induced a myriad of responses to the levels typically observed in tolerant plants. Its application activated the transcription of defence gene's regulators, pathogen-related genes and genes involved in phytoalexins biosynthesis. Moreover, EPA application resulted in the alteration of the leaf FA profile, likely by impacting biosynthetic, unsaturation and turnover processes. Although both molecules were able to trigger grapevine defence mechanisms, EPA induced a more robust and prolonged response. This finding establishes EPA as a promising elicitor for an effectively managing grapevine downy mildew diseases.

Oomycete Nudix effectors display WY-Nudix conformation and mRNA decapping activity.

Oomycete Nudix effectors have characteristics of independent evolution, but adopt a conserved WY-Nudix conformation. Furthermore, multiple oomycete Nudix effectors exhibit mRNA decapping activity.

A Loop-Mediated Isothermal Amplification (LAMP) Assay for the Detection of Bremia lactucae in the Field.

A real-time loop-mediated isothermal amplification (LAMP) assay for the detection of Bremia lactucae, the causal pathogen of lettuce downy mildew, was developed and validated to aid in-field detection of airborne inoculum. Assay specificity was confirmed against a range of other pathogenic oomycete and fungal spp., and sensitivity of the assay for the detection of DNA extracted from sporangia was evaluated. The B. lactucae LAMP assay reliably detected DNA equivalent to 1 spore/reaction (16.7 pg DNA/reaction). Following extraction of DNA from Rotorod air samplers, to which sporangial suspensions were added, the assay reliably detected 25 sporangia/Rotorod. Detection of airborne inoculum of B. lactucae collected through the season from air samplers deployed in-field in plots infected with B. lactucae and in commercial lettuce fields in Scotland over two growing seasons was assessed. The method can be deployed on samples collected from commercial lettuce production to inform disease management strategies and limit the use of unnecessary prophylactic pesticide applications.

Macroalgal eukaryotic microbiome composition indicates novel phylogenetic diversity and broad host spectrum of oomycete pathogens.

Seaweeds are important components of marine ecosystems with emerging potential in aquaculture and as sources of biofuel, food products and pharmacological compounds. However, an increasingly recognised threat to natural and industrial seaweed populations is infection with parasitic single-celled eukaryotes from the relatively understudied oomycete lineage. Here we examine the eukaryomes of diverse brown, red and green marine macroalgae collected from polar (Baffin Island), cold-temperate (Falkland Islands) and tropical (Ascension Island) locations, with a focus on oomycete and closely related diatom taxa. Using 18S rRNA gene amplicon sequencing, we show unexpected genetic and taxonomic diversity of the eukaryomes, a strong broad-brush association between eukaryome composition and geographic location, and some evidence of association between eukaryome structure and macroalgal phylogenetic relationships (phylosymbiosis). However, the oomycete fraction of the eukaryome showed disparate patterns of diversity and structure, highlighting much weaker association with geography and no evidence of phylosymbiosis. We present several novel haplotypes of the most common oomycete Eurychasma dicksonii and report for the first time a cosmopolitan distribution and absence of host specificity of this important pathogen. This indicates rich diversity in macroalgal oomycete pathogens and highlights that these pathogens may be generalist and highly adaptable to diverse environmental conditions.

ATR2C ala2 from Arabidopsis-infecting downy mildew requires 4 TIR-NLR immune receptors for full recognition.

Arabidopsis Col-0 RPP2A and RPP2B confer recognition of Arabidopsis downy mildew (Hyaloperonospora arabidopsidis [Hpa]) isolate Cala2, but the identity of the recognized ATR2Cala2 effector was unknown. To reveal ATR2Cala2, an F2 population was generated from a cross between Hpa-Cala2 and Hpa-Noks1. We identified ATR2Cala2 as a non-canonical RxLR-type effector that carries a signal peptide, a dEER motif, and WY domains but no RxLR motif. Recognition of ATR2Cala2 and its effector function were verified by biolistic bombardment, ectopic expression and Hpa infection. ATR2Cala2 is recognized in accession Col-0 but not in Ler-0 in which RPP2A and RPP2B are absent. In ATR2Emoy2 and ATR2Noks1 alleles, a frameshift results in an early stop codon. RPP2A and RPP2B are essential for the recognition of ATR2Cala2. Stable and transient expression of ATR2Cala2 under 35S promoter in Arabidopsis and Nicotiana benthamiana enhances disease susceptibility. Two additional Col-0 TIR-NLR (TNL) genes (RPP2C and RPP2D) adjacent to RPP2A and RPP2B are quantitatively required for full resistance to Hpa-Cala2. We compared RPP2 haplotypes in multiple Arabidopsis accessions and showed that all four genes are present in all ATR2Cala2-recognizing accessions.

Complete telomere-to-telomere genomes uncover virulence evolution conferred by chromosome fusion in oomycete plant pathogens.

Variations in chromosome number are occasionally observed among oomycetes, a group that includes many plant pathogens, but the emergence of such variations and their effects on genome and virulence evolution remain ambiguous. We generated complete telomere-to-telomere genome assemblies for Phytophthora sojae, Globisporangium ultimum, Pythium oligandrum, and G. spinosum. Reconstructing the karyotype of the most recent common ancestor in Peronosporales revealed that frequent chromosome fusion and fission drove changes in chromosome number. Centromeres enriched with Copia-like transposons may contribute to chromosome fusion and fission events. Chromosome fusion facilitated the emergence of pathogenicity genes and their adaptive evolution. Effectors tended to duplicate in the sub-telomere regions of fused chromosomes, which exhibited evolutionary features distinct to the non-fused chromosomes. By integrating ancestral genomic dynamics and structural predictions, we have identified secreted Ankyrin repeat-containing proteins (ANKs) as a novel class of effectors in P. sojae. Phylogenetic analysis and experiments further revealed that ANK is a specifically expanded effector family in oomycetes. These results revealed chromosome dynamics in oomycete plant pathogens, and provided novel insights into karyotype and effector evolution.

Proteomic analysis revealed that the oomyceticide phosphite exhibits multi-modal action in an oomycete pathosystem.

Phytopathogenic oomycetes constitute some of the most devastating plant pathogens and cause significant crop and horticultural yield and economic losses. The phytopathogen Phytophthora cinnamomi causes dieback disease in native vegetation and several crops. The most commonly used chemical to control P. cinnamomi is the oomyceticide phosphite. Despite its widespread use, the mode of action of phosphite is not well understood and it is unclear whether it targets the pathogen, the host, or both. Resistance to phosphite is emerging in P. cinnamomi isolates and other oomycete phytopathogens. The mode of action of phosphite on phosphite-sensitive and resistant isolates of the pathogen and through a model host was investigated using label-free quantitative proteomics. In vitro treatment of sensitive P. cinnamomi isolates with phosphite hinders growth by interfering with metabolism, signalling and gene expression; traits that are not observed in the resistant isolate. When the model host Lupinus angustifolius was treated with phosphite, proteins associated with photosynthesis, carbon fixation and lipid metabolism in the host were enriched. Increased production of defence-related proteins was also observed in the plant. We hypothesise the multi-modal action of phosphite and present two models constructed using comparative proteomics that demonstrate mechanisms of pathogen and host responses to phosphite. SIGNIFICANCE: Phytophthora cinnamomi is a significant phytopathogenic oomycete that causes root rot (dieback) in a number of horticultural crops and a vast range of native vegetation. Historically, areas infected with phosphite have been treated with the oomyceticide phosphite despite its unknown mode of action. Additionally, overuse of phosphite has driven the emergence of phosphite-resistant isolates of the pathogen. We conducted a comparative proteomic study of a sensitive and resistant isolate of P. cinnamomi in response to treatment with phosphite, and the response of a model host, Lupinus angustifolius, to phosphite and its implications on infection. The present study has allowed for a deeper understanding of the bimodal action of phosphite, suggested potential biochemical factors contributing to chemical resistance in P. cinnamomi, and unveiled possible drivers of phosphite-induced host plant immunity to the pathogen.

Oomycete Metabolism Is Highly Dynamic and Reflects Lifestyle Adaptations.

The selective pressure of pathogen-host symbiosis drives adaptations. How these interactions shape the metabolism of pathogens is largely unknown. Here, we use comparative genomics to systematically analyze the metabolic networks of oomycetes, a diverse group of eukaryotes that includes saprotrophs as well as animal and plant pathogens, with the latter causing devastating diseases with significant economic and/or ecological impacts. In our analyses of 44 oomycete species, we uncover considerable variation in metabolism that can be linked to lifestyle differences. Comparisons of metabolic gene content reveal that plant pathogenic oomycetes have a bipartite metabolism consisting of a conserved core and an accessory set. The accessory set can be associated with the degradation of defense compounds produced by plants when challenged by pathogens. Obligate biotrophic oomycetes have smaller metabolic networks, and taxonomically distantly related biotrophic lineages display convergent evolution by repeated gene losses in both the conserved as well as the accessory set of metabolisms. When investigating to what extent the metabolic networks in obligate biotrophs differ from those in hemibiotrophic plant pathogens, we observe that the losses of metabolic enzymes in obligate biotrophs are not random and that gene losses predominantly influence the terminal branches of the metabolic networks. Our analyses represent the first metabolism-focused comparison of oomycetes at this scale and will contribute to a better understanding of the evolution of oomycete metabolism in relation to lifestyle adaptation. Numerous oomycete species are devastating plant pathogens that cause major damage in crops and natural ecosystems. Their interactions with hosts are shaped by strong selection, but how selection affects adaptation of the primary metabolism to a pathogenic lifestyle is not yet well established. By pan-genome and metabolic network analyses of distantly related oomycete pathogens and their nonpathogenic relatives, we reveal considerable lifestyle- and lineage-specific adaptations. This study contributes to a better understanding of metabolic adaptations in pathogenic oomycetes in relation to lifestyle, host, and environment, and the findings will help in pinpointing potential targets for disease control. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

The pathogenicity of Plasmopara viticola: a review of evolutionary dynamics, infection strategies and effector molecules.

Oomycetes are filamentous organisms that resemble fungi in terms of morphology and life cycle, primarily due to convergent evolution. The success of pathogenic oomycetes lies in their ability to adapt and overcome host resistance, occasionally transitioning to new hosts. During plant infection, these organisms secrete effector proteins and other compounds during plant infection, as a molecular arsenal that contributes to their pathogenic success. Genomic sequencing, transcriptomic analysis, and proteomic studies have revealed highly diverse effector repertoires among different oomycete pathogens, highlighting their adaptability and evolution potential.The obligate biotrophic oomycete Plasmopara viticola affects grapevine plants (Vitis vinifera L.) causing the downy mildew disease, with significant economic impact. This disease is devastating in Europe, leading to substantial production losses. Even though Plasmopara viticola is a well-known pathogen, to date there are scarce reviews summarising pathogenicity, virulence, the genetics and molecular mechanisms of interaction with grapevine.This review aims to explore the current knowledge of the infection strategy, lifecycle, effector molecules, and pathogenicity of Plasmopara viticola. The recent sequencing of the Plasmopara viticola genome has provided new insights into understanding the infection strategies employed by this pathogen. Additionally, we will highlight the contributions of omics technologies in unravelling the ongoing evolution of this oomycete, including the first in-plant proteome analysis of the pathogen.