Project description:Pierce's disease, caused by the bacterium Xylella fastidiosa, is one of the most devastating diseases of cultivated grapes. To test the long-standing hypothesis that Pierce's disease results from pathogen-induced drought stress, we used the Affymetrix Vitis GeneChip to compare the transcriptional response of Vitis vinifera to Xylella infection, water deficit, or a combination of the two stresses. The results reveal a massive redirection of gene transcription involving 822 genes with a minimum 2-fold change (p<0.05), including the upregulation of transcripts for phenylpropanoid and flavonoid biosynthesis, pathogenesis related (PR) proteins, absisic acid (ABA)/jasmonic acid (JA)-responsive transcripts, and down-regulation of transcripts related to photosynthesis, growth and nutrition. Although the transcriptional response of plants to Xylella infection was largely distinct from the response of healthy plants to water stress, we find that 138 of the pathogen-induced genes exhibited a significantly stronger transcriptional response when plants were simultaneously exposed to infection and drought stress, suggesting a strong interaction between disease and water deficit. This interaction between drought stress and disease was mirrored in planta at the physiological level for aspects of water relations and photosynthesis, and in terms of the severity of disease symptoms and the extent of pathogen colonization, providing a molecular correlation of the classical concept of the disease triangle where environment impacts disease severity. Mature leaves were sampled from 2-year old V. vinifera cv. Cabernet sauvignon clone 8 vines 4 and 8 weeks post-mock or inoculation with Xylella fastidiosa (Pierce's disease). Vines were grown in growth chambers under non-water limiting and water limiting conditions (moderate and severe water stress)
Project description:Pierce’s disease, caused by the bacterium Xylella fastidiosa, is one of the most devastating diseases of cultivated grapes. To test the long-standing hypothesis that Pierce’s disease results from pathogen-induced drought stress, we used the Affymetrix Vitis GeneChip to compare the transcriptional response of Vitis vinifera to Xylella infection, water deficit, or a combination of the two stresses. The results reveal a massive redirection of gene transcription involving 822 genes with a minimum 2-fold change (p<0.05), including the upregulation of transcripts for phenylpropanoid and flavonoid biosynthesis, pathogenesis related (PR) proteins, absisic acid (ABA)/jasmonic acid (JA)-responsive transcripts, and down-regulation of transcripts related to photosynthesis, growth and nutrition. Although the transcriptional response of plants to Xylella infection was largely distinct from the response of healthy plants to water stress, we find that 138 of the pathogen-induced genes exhibited a significantly stronger transcriptional response when plants were simultaneously exposed to infection and drought stress, suggesting a strong interaction between disease and water deficit. This interaction between drought stress and disease was mirrored in planta at the physiological level for aspects of water relations and photosynthesis, and in terms of the severity of disease symptoms and the extent of pathogen colonization, providing a molecular correlation of the classical concept of the disease triangle where environment impacts disease severity.
Project description:The objective of the study was to uncover the developmental dynamics in the artificially induced somatic embryogenesis of Vitis vinifera on the transcriptome level.
Project description:Vitis vinifera endogenous small RNAs Size fractionated small RNA from total RNA extracts of Vitis vinifera leaves, inflorescences, tendrils and small berries were ligated to adapters, purified again and reverse transcribed. After PCR amplification the sample was subjected to Solexa/Illumina high throughput pyrosequencing. Please see www.illumina.com for details of the sequencing technology.
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.