RESUMEN
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.
Asunto(s)
Factor 1 de Ribosilacion-ADP , Nicotiana , Oomicetos , Enfermedades de las Plantas , Inmunidad de la Planta , Proteínas de Plantas , Vitis , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/inmunología , Nicotiana/genética , Nicotiana/microbiología , Nicotiana/inmunología , Nicotiana/metabolismo , Oomicetos/fisiología , Vitis/genética , Vitis/microbiología , Vitis/metabolismo , Vitis/inmunología , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Factor 1 de Ribosilacion-ADP/metabolismo , Factor 1 de Ribosilacion-ADP/genética , Regulación de la Expresión Génica de las Plantas , Interacciones Huésped-PatógenoRESUMEN
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.
Asunto(s)
Ciclopentanos , Ácido Eicosapentaenoico , Oomicetos , Oxilipinas , Vitis , Vitis/microbiología , Vitis/metabolismo , Vitis/genética , Vitis/inmunología , Vitis/efectos de los fármacos , Ácido Eicosapentaenoico/metabolismo , Oomicetos/fisiología , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/inmunología , Inmunidad de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/inmunología , Hojas de la Planta/microbiologíaRESUMEN
Oomycete Nudix effectors have characteristics of independent evolution, but adopt a conserved WY-Nudix conformation. Furthermore, multiple oomycete Nudix effectors exhibit mRNA decapping activity.
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Oomicetos , Oomicetos/fisiología , ARN Mensajero/metabolismo , ARN Mensajero/genética , Caperuzas de ARN/metabolismoRESUMEN
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.
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Oomicetos , Enfermedades de las Plantas , Vitis , Oomicetos/patogenicidad , Oomicetos/fisiología , Enfermedades de las Plantas/microbiología , Vitis/microbiología , Vitis/genética , Virulencia , Evolución Biológica , Interacciones Huésped-PatógenoRESUMEN
Interactions between various microbial pathogens including viruses, bacteria, fungi, oomycetes, and their plant hosts have traditionally been the focus of phytopathology. In recent years, a significant and growing interest in the study of eukaryotic microorganisms not classified among fungi or oomycetes has emerged. Many of these protists establish complex interactions with photosynthetic hosts, and understanding these interactions is crucial in understanding the dynamics of these parasites within traditional and emerging types of farming, including marine aquaculture. Many phytopathogenic protists are biotrophs with complex polyphasic life cycles, which makes them difficult or impossible to culture, a fact reflected in a wide gap in the availability of comprehensive genomic data when compared to fungal and oomycete plant pathogens. Furthermore, our ability to use available genomic resources for these protists is limited by the broad taxonomic distance that these organisms span, which makes comparisons with other genomic datasets difficult. The current rapid progress in genomics and computational tools for the prediction of protein functions and interactions is revolutionizing the landscape in plant pathology. This is also opening novel possibilities, specifically for a deeper understanding of protist effectors. Tools like AlphaFold2 enable structure-based function prediction of effector candidates with divergent protein sequences. In turn, this allows us to ask better biological questions and, coupled with innovative experimental strategies, will lead into a new era of effector research, especially for protists, to expand our knowledge on these elusive pathogens and their interactions with photosynthetic hosts. [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.
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Fotosíntesis , Enfermedades de las Plantas , Plantas , Plantas/parasitología , Plantas/microbiología , Enfermedades de las Plantas/parasitología , Enfermedades de las Plantas/microbiología , Interacciones Huésped-Patógeno , Eucariontes/genética , Genómica , Oomicetos/fisiología , Oomicetos/patogenicidad , Oomicetos/genéticaRESUMEN
A phenomenon of pathogenicity attenuation of Plasmopara viticola was consistently observed during its subculture on grape. To clarify the causes of attenuated pathogenicity of P. viticola, culturable microbes were isolated from the P. viticola mass (mycelia, sporangiophores, and sporangia) in each generation and tested for their biocontrol efficacies on grape downy mildew (GDM). The results showed that the incidence of GDM decreased with the increase in the number of subculture times on both vineyard-collected leaves and grape leaves from in vitro-grown seedlings. The number of culturable microbial taxa on the surface of P. viticola decreased, whereas the population densities of four specific strains (i.e., K2, K7, P1, and P5) increased significantly with the increase in subculture times. Compared with the control, the biocontrol efficacies of the bacterial strain K2 reached 87.5%, and those of both fungal strains P1 and P5 reached 100.0%. Based on morphological characteristics and molecular sequences, strains K2, P1, and P5 were identified as Curtobacterium herbarum, Thecaphora amaranthi, and Acremonium sclerotigenum, respectively, and these three strains survived very well and multiplied on the surface of P. viticola. As the number of times P. viticola was subcultured increased, all three of these strains became the predominant strains, leading to greater P. viticola inhibition, attenuated P. viticola pathogenicity, and effective GDM biological control. To the best of our knowledge, this is the first report of C. herbarum and T. amaranthi having biological control activity against GDM.
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Oomicetos , Enfermedades de las Plantas , Vitis , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Oomicetos/patogenicidad , Oomicetos/fisiología , Vitis/microbiología , Hojas de la Planta/microbiología , Agentes de Control Biológico , Control Biológico de Vectores , VirulenciaRESUMEN
Nonmycorrhizal cluster root-forming species enhance the phosphorus (P) acquisition of mycorrhizal neighbours in P-impoverished megadiverse systems. However, whether mycorrhizal plants facilitate the defence of nonmycorrhizal plants against soil-borne pathogens, in return and via their symbiosis, remains unknown. We characterised growth and defence-related compounds in Banksia menziesii (nonmycorrhizal) and Eucalyptus todtiana (ectomycorrhizal, ECM) seedlings grown either in monoculture or mixture in a multifactorial glasshouse experiment involving ECM fungi and native oomycete pathogens. Roots of B. menziesii had higher levels of phytohormones (salicylic and jasmonic acids, jasmonoyl-isoleucine and 12-oxo-phytodienoic acid) than E. todtiana which further activated a salicylic acid-mediated defence response in roots of B. menziesii, but only in the presence of ECM fungi. We also found that B. menziesii induced a shift in the defence strategy of E. todtiana, from defence-related secondary metabolites (phenolic and flavonoid) towards induced phytohormone response pathways. We conclude that ECM fungi play a vital role in the interactions between mycorrhizal and nonmycorrhizal plants in a severely P-impoverished environment, by introducing a competitive component within the facilitation interaction between the two plant species with contrasting nutrient-acquisition strategies. This study sheds light on the interplay between beneficial and detrimental soil microbes that shape plant-plant interaction in severely nutrient-impoverished ecosystems.
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Micorrizas , Oomicetos , Fósforo , Micorrizas/fisiología , Fósforo/metabolismo , Oomicetos/fisiología , Oomicetos/patogenicidad , Eucalyptus/microbiología , Eucalyptus/fisiología , Raíces de Plantas/microbiología , Raíces de Plantas/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Plantones/microbiología , Simbiosis/fisiología , Especificidad de la Especie , AmbienteRESUMEN
Vitis vinifera L. is highly susceptible to the biotrophic pathogen Plasmopara viticola. To control the downy mildew disease, several phytochemicals are applied every season. Recent European Union requirements to reduce the use of chemicals in viticulture have made it crucial to use alternative and more sustainable approaches to control this disease. Our previous studies pinpoint the role of fatty acids and lipid signalling in the establishment of an incompatible interaction between grapevine and P. viticola. To further understand the mechanisms behind lipid involvement in an effective defence response we have analysed the expression of several genes related to lipid metabolism in three grapevine genotypes: Chardonnay (susceptible); Regent (tolerant), harbouring an Rpv3-1 resistance loci; and Sauvignac (resistant) that harbours a pyramid of Rpv12 and Rpv3-1 resistance loci. A highly aggressive P. viticola isolate was used (NW-10/16). Moreover, we have characterised the grapevine phospholipases C and D gene families and monitored fatty acid modulation during infection. Our results indicate that both susceptible and resistant grapevine hosts did not present wide fatty acid or gene expression modulation. The modulation of genes associated with lipid signalling and fatty acids seems to be specific to Regent, which raises the hypothesis of being specifically linked to the Rpv3 loci. In Sauvignac, the Rpv12 may be dominant concerning the defence response, and, thus, this genotype may present the activation of other pathways rather than lipid signalling.
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Oomicetos , Peronospora , Humanos , Resistencia a la Enfermedad/genética , Oomicetos/fisiología , Ácidos Grasos , LípidosRESUMEN
BACKGROUND: Downy mildew of foxtail millet, which is caused by the biotrophic oomycete Sclerospora graminicola (Sacc.) Schroeter, is one of the most disruptive diseases. The foxtail millet-S. graminicola interaction is largely unexplored. Transcriptome sequencing technology can help to reveal the interaction mechanism between foxtail millet and its pathogens. RESULTS: Transmission electron microscopy observations of leaves infected with S. graminicola showed that the structures of organelles in the host cells gradually became deformed and damaged, or even disappeared from the 3- to 7-leaf stages. However, organelles in the leaves of resistant variety were rarely damaged. Moreover, the activities of seven cell wall degrading enzymes in resistant and susceptible varieties were also quite different after pathogen induction and most of enzymes activities were significantly higher in the susceptible variety JG21 than in the resistant variety G1 at all stages. Subsequently, we compared the transcriptional profiles between the G1 and JG21 in response to S. graminicola infection at 3-, 5-, and 7-leaf stages using RNA-Seq technology. A total of 473 and 1433 differentially expressed genes (DEGs) were identified in the resistant and susceptible varieties, respectively. The pathway analysis of the DEGs showed that the highly enriched categories were related to glutathione metabolism, plant hormone signalling, phenylalanine metabolism, and cutin, suberin and wax biosynthesis. Some defence-related genes were also revealed in the DEGs, including leucine-rich protein kinase, Ser/Thr protein kinase, peroxidase, cell wall degrading enzymes, laccases and auxin response genes. Our results also confirmed the linkage of transcriptomic data with qRT-PCR data. In particular, LRR protein kinase encoded by Seita.8G131800, Ser/Thr protein kinase encoded by Seita.2G024900 and Seita. 2G024800, which have played an essential resistant role during the infection by S. graminicola. CONCLUSIONS: Transcriptome sequencing revealed that host resistance to S. graminicola was likely due to the activation of defence-related genes, such as leucine-rich protein kinase and Ser/Thr protein kinase. Our study identified pathways and genes that contribute to the understanding of the interaction between foxtail millet and S. graminicola at the transcriptomic level. The results will help us better understand the resistance mechanism of foxtail millet against S. graminicola.
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Oomicetos , Pennisetum , Setaria (Planta) , Setaria (Planta)/genética , Setaria (Planta)/metabolismo , Leucina/genética , Pennisetum/genética , Oomicetos/fisiología , Perfilación de la Expresión Génica , Proteínas Quinasas/genética , TranscriptomaRESUMEN
KEY MESSAGE: The dm5.3 major-effect QTL in cucumber encodes a homolog of Arabidopsis sigma factor binding protein 1 (CsSIB1). CsSIB1 positively regulates defense responses against downy mildew in cucumber through the salicylic acid (SA) biosynthesis/signaling pathway. Downy mildew (DM) caused by the oomycete pathogen Pseudoperonospora cubensis is an important disease of cucumber and other cucurbits. Our knowledge on molecular mechanisms of DM resistance is still limited. In this study, we reported identification and functional characterization of the candidate gene for the major-effect QTL, dm5.3 for DM resistance originated from PI 197088. The dm5.3 QTL was Modelized through marker-assisted development of near isogenic lines (NILs). NIL-derived segregating populations were used for fine mapping which narrowed the dm5.3 locus down to a 144 kb region. Based on multiple lines of evidence, we show that CsSIB1 (CsGy5G027140) that encodes the VQ motif-containing sigma factor binding protein 1 as the most likely candidate for dm5.3. Local association analysis identified a haplotype consisting of 7 SNPs inside the coding and promoter region of CsSIB1 that was associated with DM resistance. Expression of CsSIB1 was up-regulated with P. cubensis infection. Transcriptome profiling of NILs in response to P. cubensis inoculation revealed key players and associated gene networks in which increased expression of CsSIB1 antagonistically promoted salicylic acid (SA) but suppressed jasmonic acid (JA) biosynthesis/signaling pathways. Our work provides novel insights into the function of CsSIB1/dm5.3 as a disease resistance (R) gene. The roles of sigma factor binding protein genes in pathogen defense in cucumber were also discussed.
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Cucumis sativus , Oomicetos , Peronospora , Cucumis sativus/genética , Cucumis sativus/metabolismo , Factor sigma/metabolismo , Enfermedades de las Plantas/genética , Oomicetos/fisiología , Resistencia a la Enfermedad/genética , Ácido Salicílico/metabolismoRESUMEN
Downy mildew, caused by Plasmopara viticola (Berk. and M. A. Curtis) Berl. and De Toni, is a serious disease of grapevines in general and King Ruby seedless cultivar in particular, affecting their growth and yield. Magnesium carbonate (MgCO3) is an antitranspirant, which induces stomatal closing and enhances plant growth and physiology. In this study, effect of foliar application of MgCO3 at 1 and 3% on plant resistance, growth, yield and physiology of grapevines (cv. King Ruby seedless) infected with downy mildew was investigated under field conditions. The obtained results showed that foliar application of MgCO3 at 3% led to upregulation of the transcription factor JERF3 (9.6-fold), and the defense-related genes GLU (6.3-fold), POD (8.7-fold), PR1 (9.6-fold), and CHI II (8.6-fold). In addition, this treatment led to a reduction in the disease severity (78%), and an increment in the yield per grapevine (20%). Furthermore, biochemical properties of berries, total contents of the photosynthetic pigments, phenolic compounds, and activities of the antioxidant enzymes peroxidase and polyphenol oxidase also enhanced. In contrast, lipid peroxidation, and H2O2 content in grapevines leaves reduced in response to MgCO3 spraying. Light microscope observations revealed that average number of closed stomata increased and the average stomatal pore area decreased in grapevines leaves as a result to MgCO3 spraying. Based on these results, we can conclude that spraying with MgCO3 at 3% has effective roles in inducing the plant resistance against downy mildew, and improving the growth and yield of grapevines.
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Oomicetos , Peronospora , Vitis , Frutas , Peróxido de Hidrógeno , Magnesio , Oomicetos/fisiología , Enfermedades de las Plantas/genética , Vitis/genéticaRESUMEN
Plant pathogens are one of the main factors hindering the breeding of cash crops. Pathogens, including oomycetes, fungus, and bacteria, secrete effectors as invasion weapons to successfully invade and propagate in host plants. Here, we review recent advances made in the field of plant-pathogen interaction models and the action mechanisms of phytopathogenic effectors. The review illustrates how effectors from different species use similar and distinct strategies to infect host plants. We classify the main action mechanisms of effectors in plant-pathogen interactions according to the infestation process: targeting physical barriers for disruption, creating conditions conducive to infestation, protecting or masking themselves, interfering with host cell physiological activity, and manipulating plant downstream immune responses. The investigation of the functioning of plant pathogen effectors contributes to improved understanding of the molecular mechanisms of plant-pathogen interactions. This understanding has important theoretical value and is of practical significance in plant pathology and disease resistance genetics and breeding.
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Oomicetos , Enfermedades de las Plantas , Productos Agrícolas , Interacciones Huésped-Patógeno , Oomicetos/fisiología , Fitomejoramiento , Enfermedades de las Plantas/microbiología , Inmunidad de la PlantaRESUMEN
BACKGROUND: Reduction of fungicide consumption in agriculture is globally recognized as a priority. Government authorities are fostering research to achieve a reduction of risks associated with conventional pesticides and promoting the development of sustainable alternatives. To address these issues, in the present study, alternative protocols for the control of downy mildew infection in grapevine were compared to the standard protocol. In the first protocol, only resistance inducers were used, comprising a single formulation with Acibenzolar S-methyl, laminarin and disodium-phosphonate. The second and third protocols followed the standard protocol but substituted phosphonates with phosphorus pentoxide and Ecklonia maxima extract. RESULTS: The results showed that at veraison downy mildew incidence and severity in all tested protocols were significantly reduced compared to nontreated controls on both canopy and bunches. Expression analysis of key genes involved in plant stress response, indicated that the two protocols for phosphites substitution induced a remodulation of salicylic acid (SA) and jasmonic acid (JA), with positive impact on yields. Analysis of the first protocol revealed that the primed state induced a short delay in bunch ripening, with a shift of carbohydrate metabolism to boost the plant defences, involving an upregulation of defence related-gene, SAR response and a decreased ROS detoxification. Additionally, analysis on the arthropods populations, in parallel with the positive results achieved using alternatives to conventional fungicides, were enriched by those showing the potential of naturally occurring predators of spider mites. CONCLUSION: This study provides practical solutions to reduce the environmental impact of treatments for the control downy mildew in viticulture. © 2022 Society of Chemical Industry.
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Artrópodos , Fungicidas Industriales , Oomicetos , Peronospora , Vitis , Animales , Resistencia a la Enfermedad/genética , Fungicidas Industriales/metabolismo , Fungicidas Industriales/farmacología , Regulación de la Expresión Génica de las Plantas , Oomicetos/fisiología , Enfermedades de las Plantas/prevención & control , Vitis/genéticaRESUMEN
Necrosis and ethylene-inducing peptide 1 (Nep1) -like proteins (NLP) are secreted by multiple taxonomically unrelated plant pathogens (bacteria, fungi, and oomycete) and are best known for inducing cell death and immune responses in dicotyledonous plants. A group of putative NLP genes from obligate biotrophic oomycete Plasmopara viticola were predicted by RNA-Seq in our previous study, but their activity has not been established. Therefore, we analyzed the P. viticola NLP (PvNLP) family and identified seven PvNLP genes. They all belong to type 1 NLP genes and form a P. viticola-specific cluster when compared with other pathogen NLP genes. The expression of PvNLPs was induced during early infection process and the expression patterns could be categorized into two groups. Agrobacterium tumefaciens-mediated transient expression assays revealed that only PvNLP7 was cytotoxic and could induce Phytophthora capsici resistance in Nicotiana benthamiana. Functional analysis showed that PvNLP4, PvNLP5, PvNLP7, and PvNLP10 significantly improved disease resistance of Arabidopsis thaliana to Hyaloperonospora arabidopsidis. Moreover, the four genes caused an inhibition of plant growth which is typically associated with enhanced immunity when over-expressed in Arabidopsis. Further research found that PvNLP7 could activate the expression of defense-related genes and its conserved NPP1 domain was critical for cell death- and immunity-inducing activity. This record of NLP genes from P. viticola showed a functional diversification, laying a foundation for further study on pathogenic mechanism of the devastating pathogen.
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Arabidopsis , Oomicetos , Phytophthora , Arabidopsis/metabolismo , Resistencia a la Enfermedad , Oomicetos/fisiología , Phytophthora/fisiología , Enfermedades de las Plantas/microbiología , Proteínas/química , Nicotiana/metabolismoRESUMEN
The simple notion 'infection causes an immune response' is being progressively refined as it becomes clear that immune mechanisms cannot be understood in isolation, but need to be considered in a more global context with other cellular and physiological processes. In part, this reflects the deployment by pathogens of virulence factors that target diverse cellular processes, such as translation or mitochondrial respiration, often with great molecular specificity. It also reflects molecular cross-talk between a broad range of host signalling pathways. Studies with the model animal C. elegans have uncovered a range of examples wherein innate immune responses are intimately connected with different homeostatic mechanisms, and can influence reproduction, ageing and neurodegeneration, as well as various other aspects of its biology. Here we provide a short overview of a number of such connections, highlighting recent discoveries that further the construction of a fully integrated view of innate immunity.
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Caenorhabditis elegans/inmunología , Inmunidad Innata , Animales , Caenorhabditis elegans/metabolismo , Oomicetos/fisiología , Transducción de Señal , SueñoRESUMEN
BACKGROUND: The high susceptibility of European grapevine cultivars (Vitis vinifera) to downy mildew (Plasmopara viticola) leads to the intensive use of fungicides in viticulture. To reduce this input, breeding programs have introgressed resistance loci from wild Vitis species into V. vinifera, resulting in new fungus-resistant grapevine cultivars (FRC). However, little is known about how these different resistance loci confer resistance and what the potential reduction in fungicide applications are likely to be if these FRCs are deployed. To ensure a durable and sustainable resistance management and breeding, detailed knowledge about the different defense mechanisms mediated by the respective Rpv (Resistance to P. viticola) resistance loci is essential. RESULTS: A comparison of the resistance mechanisms mediated by the Rpv3-1, Rpv10 and/or Rpv12-loci revealed an early onset of programmed cell death (PCD) at 8 hours post infection (hpi) in Rpv12-cultivars and 12 hpi in Rpv10-cultivars, whereas cell death was delayed in Rpv3-cultivars and was not observed until 28 hpi. These temporal differences correlated with an increase in the trans-resveratrol level and the formation of hydrogen peroxide shortly before onset of PCD. The differences in timing of onset of Rpv-loci specific defense reactions following downy mildew infection could be responsible for the observed differences in hyphal growth, sporulation and cultivar-specific susceptibility to this pathogen in the vineyard. Hereby, Rpv3- and Rpv12/Rpv3-cultivars showed a potential for a significant reduction of fungicide applications, depending on the annual P. viticola infection pressure and the Rpv-loci. Furthermore, we report on the discovery of a new P. viticola isolate that is able to overcome both Rpv3- and Rpv12-mediated resistance. CONCLUSION: This study reveals that differences in the timing of the defense reaction mediated by the Rpv3-, Rpv10- and Rpv12-loci, result in different degrees of natural resistance to downy mildew in field. Vineyard trials demonstrate that Rpv12/Rpv3- and Rpv3-cultivars are a powerful tool to reduce the dependence of grape production on fungicide applications. Furthermore, this study indicates the importance of sustainable breeding and plant protection strategies based on resistant grapevine cultivars to reduce the risk of new P. viticola isolates that are able to overcome the respective resistance mechanism.
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Resistencia a la Enfermedad/genética , Oomicetos/fisiología , Enfermedades de las Plantas/inmunología , Proteínas de Plantas/metabolismo , Vitis/genética , Apoptosis , Fungicidas Industriales/farmacología , Sitios Genéticos/genética , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/parasitología , Hojas de la Planta/genética , Hojas de la Planta/inmunología , Hojas de la Planta/parasitología , Proteínas de Plantas/genética , Vitis/inmunología , Vitis/parasitologíaRESUMEN
The oomycete Albugo candida causes white rust of Brassicaceae, including vegetable and oilseed crops, and wild relatives such as Arabidopsis thaliana. Novel White Rust Resistance (WRR) genes from Arabidopsis enable new insights into plant/parasite co-evolution. WRR4A from Arabidopsis accession Columbia (Col-0) provides resistance to many but not all white rust races, and encodes a nucleotide-binding, leucine-rich repeat immune receptor. Col-0 WRR4A resistance is broken by AcEx1, an isolate of A. candida. We identified an allele of WRR4A in Arabidopsis accession Øystese-0 (Oy-0) and other accessions that confers full resistance to AcEx1. WRR4AOy-0 carries a C-terminal extension required for recognition of AcEx1, but reduces recognition of several effectors recognized by the WRR4ACol-0 allele. WRR4AOy-0 confers full resistance to AcEx1 when expressed in the oilseed crop Camelina sativa.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Resistencia a la Enfermedad/genética , Variación Genética , Oomicetos/fisiología , Enfermedades de las Plantas/inmunología , Alelos , Secuencia de Aminoácidos , Arabidopsis/inmunología , Proteínas de Arabidopsis/genética , Camellia/genética , Camellia/inmunología , Hojas de la Planta , Plantas Modificadas Genéticamente , Alineación de Secuencia , Nicotiana/genética , Nicotiana/inmunologíaRESUMEN
Cucurbit downy mildew (DM), caused by the obligate biotroph Pseudoperonospora cubensis, is a destructive disease in cucumber. A valuable source of DM resistance is the Indian cucumber accession PI 197088, which harbours several quantitative trait loci (QTLs) contributing to quantitatively inherited DM resistance. With a combination of fine-mapping and transcriptomics, we identified Amino Acid Permease 2A (CsAAP2A) as a candidate gene for QTL DM4.1.3. Whole-genome and Sanger sequencing revealed the insertion of a Cucumis Mu-like element (CUMULE) transposon in the allele of the resistant near-isogenic line DM4.1.3. To confirm whether loss of CsAAP2A contributes to partial DM resistance, we performed targeting induced local lesions in genomes on a DM-susceptible cucumber genotype to identify an additional csaap2a mutant, which indeed was partially DM resistant. In view of the loss of the putative function as amino acid transporter, we measured amino acids in leaves. We found that DM-inoculated leaves of line DM4.1.3 (with the csaap2a mutation) contained significantly fewer amino acids than wild-type cucumber. The decreased flow of amino acids towards infected leaves in csaap2a plants compared to the wild type might explain the resistant phenotype of the mutant, as this would limit the available nutrients for the pathogen and thereby its fitness. To examine whether AAP genes play a conserved role as susceptibility factors in plant-oomycete interactions, we made targeted mutations in two AAP genes from tomato and studied the effect on susceptibility to Phytophthora infestans. We conclude that not only CsAAP2A but also SlAAP5A/SlAAP5B are susceptibility genes for oomycete pathogens.
Asunto(s)
Sistemas de Transporte de Aminoácidos/metabolismo , Cucumis sativus/genética , Interacciones Huésped-Patógeno , Oomicetos/fisiología , Enfermedades de las Plantas/parasitología , Solanum lycopersicum/genética , Alelos , Sistemas de Transporte de Aminoácidos/genética , Transporte Biológico , Cucumis sativus/parasitología , Cucumis sativus/fisiología , Elementos Transponibles de ADN/genética , Resistencia a la Enfermedad/genética , Susceptibilidad a Enfermedades , Genotipo , Solanum lycopersicum/parasitología , Mutación , Fenotipo , Hojas de la Planta/genética , Hojas de la Planta/parasitología , Hojas de la Planta/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sitios de Carácter Cuantitativo/genéticaRESUMEN
Pseudoperonospora humuli is an obligate biotrophic oomycete that causes downy mildew, one of the most devastating diseases of cultivated hop, Humulus lupulus. Downy mildew occurs in all production areas of the crop in the Northern Hemisphere and Argentina. The pathogen overwinters in hop crowns and roots, and causes considerable crop loss. Downy mildew is managed by sanitation practices, planting of resistant cultivars, and fungicide applications. However, the scarcity of sources of host resistance and fungicide resistance in pathogen populations complicates disease management. This review summarizes the current knowledge on the symptoms of the disease, life cycle, virulence factors, and management of hop downy mildew, including various forecasting systems available in the world. Additionally, recent developments in genomics and effector discovery, and the future prospects of using such resources in successful disease management are also discussed. TAXONOMY: Class: Oomycota; Order: Peronosporales; Family: Peronosporaceae; Genus: Pseudoperonospora; Species: Pseudoperonospora humuli. DISEASE SYMPTOMS: The disease is characterized by systemically infected chlorotic shoots called "spikes". Leaf symptoms and signs include angular chlorotic lesions and profuse sporulation on the abaxial side of the leaf. Under severe disease pressure, dark brown discolouration or lesions are observed on cones. Infected crowns have brown to black streaks when cut open. Cultivars highly susceptible to crown rot may die at this phase of the disease cycle without producing shoots. However, foliar symptoms may not be present on plants with systemically infected root systems. INFECTION PROCESS: Pathogen mycelium overwinters in buds and crowns, and emerges on infected shoots in spring. Profuse sporulation occurs on infected tissues and sporangia are released and dispersed by air currents. Under favourable conditions, sporangia germinate and produce biflagellate zoospores that infect healthy tissue, thus perpetuating the infection cycle. Though oospores are produced in infected tissues, their role in the infection cycle is not defined. CONTROL: Downy mildew on hop is managed by a combination of sanitation practices and timely fungicide applications. Forecasting systems are used to time fungicide applications for successful management of the disease. USEFUL WEBSITES: https://content.ces.ncsu.edu/hop-downy-mildew (North Carolina State University disease factsheet), https://www.canr.msu.edu/resources/michigan-hop-management-guide (Michigan Hop Management Guide), http://uspest.org/risk/models (Oregon State University Integrated Plant Protection Center degree-day model for hop downy mildew), https://www.usahops.org/cabinet/data/Field-Guide.pdf (Field Guide for Integrated Pest Management in Hops).
Asunto(s)
Humulus/parasitología , Oomicetos/fisiología , Enfermedades de las Plantas/parasitología , Resistencia a la Enfermedad , Fungicidas Industriales , Humulus/inmunología , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/prevención & controlRESUMEN
During 450 million years of diversification on land, plants and microbes have evolved together. This is reflected in today's continuum of associations, ranging from parasitism to mutualism. Through phylogenetics, cell biology, and reverse genetics extending beyond flowering plants into bryophytes, scientists have started to unravel the genetic basis and evolutionary trajectories of plant-microbe associations. Protection against pathogens and support of beneficial, symbiotic, microorganisms are sustained by a blend of conserved and clade-specific plant mechanisms evolving at different speeds. We propose that symbiosis consistently emerges from the co-option of protection mechanisms and general cell biology principles. Exploring and harnessing the diversity of molecular mechanisms used in nonflowering plant-microbe interactions may extend the possibilities for engineering symbiosis-competent and pathogen-resilient crops.