Project description:WRKY genes are transcription factors involved in plant response to pathogen attacks in many plant species. These proteins have been shown to activate expression of defence genes in a salicylic acid- and/or jasmonic acid-dependent signalling pathway. To understand the molecular mechanisms involved in grapevine defence, we previously identified a WRKY gene, VvWRKY1, which was able to enhance tolerance to fungal pathogens when overexpressed in tobacco. To elucidate its role in grapevine, we generated transgenic grapevines that overexpress VvWRKY1. Microarray analyses were performed to compare global gene expression in leaves of the transgenic and wild-type lines. Results showed that expression of genes encoding defence-related proteins was enhanced in the transgenic 35S::VvWRKY1 line. Quantitative RT-PCR analysis confirmed that three genes putatively involved in jasmonic acid signalling pathway, two genes encoding JASMONATE ZIM-domain (JAZ) proteins and one lipoxygenase, are over-expressed. The ability of VvWRKY1 to trans-activate their corresponding promoters was confirmed by transient expression assay in grape protoplasts. After challenging with the downy mildew pathogen Plasmopara viticola, resistance was enhanced in the transgenic line compared to the wild-type line. These results suggest that VvWRKY1 transcription factor is able to control plant disease resistance to one of the main grapevine pathogen by activating jasmonic acid signalling pathway in grapevine.
Project description:Study of gene expression during Plasmopara viticola infection in the resistant Vitis vinifera cultivar 'Regent'. The oomycete fungus Plasmopara viticola (Berk. et Curt.) Berl. et de Toni is responsible for grapevine downy mildew disease. Most of the cultivated grapevines are sensitive to this pathogen, thus requiring intensive fungicide treatments. The molecular basis of resistance to this pathogen is poorly understood. We have carried out a cDNA microarray transcriptome analysis to identify grapevine genes associated with resistance traits. Early transcriptional changes associated with downy mildew infection in the resistant Vitis vinifera cultivar ‘Regent’, when compared to the susceptible cultivar ‘Trincadeira’, were analyzed. Transcript levels were measured at three time-points: 0, 6 and 12 hours post inoculation (hpi). Our data indicate that resistance in V. vinifera ‘Regent’ is induced after infection. This study provides the identification of several candidate genes that may be related to ‘Regent’ defense mechanisms, allowing a better understanding of this cultivar's resistance traits.
Project description:Downy mildew, caused by the obligate biotrophic oomycete Plasmopara viticola, is one of the most destructive grapevine diseases worldwide, constituting a major challenge to viticulture. Because an increasing number of pesticides are removed from market due to their impact on human health and/or the environment, there is an increasing need for alternative strategies to control fungal diseases. Silica nanoparticles (SiO2 NPs) and Frangula anlus extract (Fa) are emerging as promising tools for sustainable plant disease management. While their ability to enhance disease resistance has been demonstrated in several crop species, their potential in grapevine (Vitis vinifera) remains poorly investigated. In this study, foliar application of SiO2 NPs and Fa significantly reduced P. viticola infection in grapevine under both controlled and field conditions. Among multiple assays to characerize their effects, transcriptomic response of SiO2 NP-treated and Fa-Treated, infected and non-infected leaves were evaluated and compared to transcriptomic response of acibenzolar-S-methyl (B) treatment, a well known plant-defence activator. Overall, these findings provide new insights into SiO2 NP-induced and Fa-induced responses in grapevine and highlight their potential for sustainable disease management.
Project description:Eutypa dieback is a vascular disease that may severely affect vineyards throughout the world. In the present work, microarrays analysis were made in order (i) to improve our knowledge of grapevine (Vitis vinifera cv. Cabernet-Sauvignon) responses to Eutypa lata, the causal agent of Eutypa dieback and (ii) to identify genes that may prevent symptom development. Qiagen/Operon grapevine microarrays bearing 14,500 probes were used to compare between three experimental conditions (in vitro, greenhouse, vineyard), foliar material of infected symptomatic plants (S+R+), infected asymptomatic plants (S-R+), and healthy plants (S-R-). These plants were characterized by symptoms notation after natural (vineyard) or experimental (in vitro, greenhouse) infection, re-isolation of the fungus located in the lignified parts, and the formal identification of E. lata mycelium by PCR. Semi-quantitative RT-PCR experiments were run to confirm the expression of some genes of interest in response to E. lata. Their expression profiles were also studied in response to other grapevine pathogens (E. necator, P. viticola, B. cinerea). (i) Five functional categories including metabolism, defense reactions, interaction with environment, transport and transcription were up-regulated in S+R+ plants compared to S-R- plants. These genes, which cannot prevent infection and symptom development, are not specific since they were also upregulated after infection by powdery mildew, downy mildew and black rot. (ii) Most of the genes that may prevent symptom development are associated with the light phase of photosynthesis. This finding is discussed in the context of previous data on the mode of action of eutypin and Eutypa secreted polypeptide fraction.
Project description:Arabidopsis does not support the growth and asexual reproduction of the barley pathogen, Blumeria graminis f. sp. hordei Bgh). A majority of germlings fail to penetrate the epidermal cell wall and papillae. To gain additional insight into this interaction, we determined whether the salicylic acid (SA) or jasmonate (JA)/ethylene (ET) defence pathways played a role in blocking barley powdery mildew infections. Only the eds1 mutant and NahG transgenics supported a modest increase in penetration success by the barley powdery mildew. We also compared the global gene expression patterns of Arabidopsis inoculated with the non-host barley powdery mildew to those inoculated with a virulent, host powdery mildew, Erysiphe cichoracearum. Genes repressed by inoculations with non-host and host powdery mildews relative to non-inoculated control plants accounted for two-thirds of the differentially expressed genes. A majority of these genes encoded components of photosynthesis and general metabolism. Consistent with this observation, Arabidopsis growth was inhibited following inoculation with Bgh, suggesting a shift in resource allocation from growth to defence. A number of defence-associated genes were induced during both interactions. These genes likely are components of basal defence responses, which do not effectively block host powdery mildew infections. In addition, genes encoding defensins, anti-microbial peptides whose expression is under the control of the JA/ET signalling pathway, were induced exclusively by non-host pathogens. Ectopic activation of JA/ET signalling protected Arabidopsis against two biotrophic host pathogens. Taken together, these data suggest that biotrophic host pathogens must either suppress or fail to elicit the JA/ET signal transduction pathway.
Project description:Study of gene expression during Plasmopara viticola infection in the resistant Vitis vinifera cultivar 'Regent'. The oomycete fungus Plasmopara viticola (Berk. et Curt.) Berl. et de Toni is responsible for grapevine downy mildew disease. Most of the cultivated grapevines are sensitive to this pathogen, thus requiring intensive fungicide treatments. The molecular basis of resistance to this pathogen is poorly understood. We have carried out a cDNA microarray transcriptome analysis to identify grapevine genes associated with resistance traits. Early transcriptional changes associated with downy mildew infection in the resistant Vitis vinifera cultivar M-bM-^@M-^XRegentM-bM-^@M-^Y, when compared to the susceptible cultivar M-bM-^@M-^XTrincadeiraM-bM-^@M-^Y, were analyzed. Transcript levels were measured at three time-points: 0, 6 and 12 hours post inoculation (hpi). Our data indicate that resistance in V. vinifera M-bM-^@M-^XRegentM-bM-^@M-^Y is induced after infection. This study provides the identification of several candidate genes that may be related to M-bM-^@M-^XRegentM-bM-^@M-^Y defense mechanisms, allowing a better understanding of this cultivar's resistance traits. 3 time points: 0, 6 and 12 hours post inoculation by P. viticola. Two cultivars: control (Trinacedira) and test (Regent). Two biological replicates were performed at 0 hpi, and 3 biological replicates at 6 and 12hpi. At 12hpi, three technical replicates also were performed.
Project description:Arabidopsis does not support the growth and asexual reproduction of the barley pathogen, Blumeria graminis f. sp. hordei Bgh). A majority of germlings fail to penetrate the epidermal cell wall and papillae. To gain additional insight into this interaction, we determined whether the salicylic acid (SA) or jasmonate (JA)/ethylene (ET) defence pathways played a role in blocking barley powdery mildew infections. Only the eds1 mutant and NahG transgenics supported a modest increase in penetration success by the barley powdery mildew. We also compared the global gene expression patterns of Arabidopsis inoculated with the non-host barley powdery mildew to those inoculated with a virulent, host powdery mildew, Erysiphe cichoracearum. Genes repressed by inoculations with non-host and host powdery mildews relative to non-inoculated control plants accounted for two-thirds of the differentially expressed genes. A majority of these genes encoded components of photosynthesis and general metabolism. Consistent with this observation, Arabidopsis growth was inhibited following inoculation with Bgh, suggesting a shift in resource allocation from growth to defence. A number of defence-associated genes were induced during both interactions. These genes likely are components of basal defence responses, which do not effectively block host powdery mildew infections. In addition, genes encoding defensins, anti-microbial peptides whose expression is under the control of the JA/ET signalling pathway, were induced exclusively by non-host pathogens. Ectopic activation of JA/ET signalling protected Arabidopsis against two biotrophic host pathogens. Taken together, these data suggest that biotrophic host pathogens must either suppress or fail to elicit the JA/ET signal transduction pathway. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs