Identification of genes expressed during the compatible interaction of grapevine with <i>Plasmopara viticola</i> through suppression subtractive hybridization (SSH)

Grapevine (<i>Vitis vinifera</i>) is the most widely cultivated and economically important fruit crop, but is susceptible to a large number of diseases. Downy mildew, caused by the obligate biotrophic oomycete pathogen <i>Plasmopara viticola</i>, is a common disease present in all regions where vines are cultivated. We used suppression subtractive hybridization (SSH) to generate two cDNA libraries enriched for transcripts induced and repressed, respectively, in the susceptible grapevine cultivar Chasselas 24 h after inoculation with <i>P. viticola</i>. Differential screening on glass slide microarrays yielded over 800 putative genes that were up-regulated in response to <i>P. viticola</i> infection and over 200 that were down-regulated. One hundred and ninety four of these, were sequenced, identified and functionally categorised. Transcript abundance of twelve genes over a 48 h time course was examined by reverse transcriptase quantitative real-time PCR (RT-qPCR). Ten of these genes were induced/enhanced by <i>P. viticola</i> challenge, confirming the results of the SSH. The vast majority of the genes identified are related to defence. Interestingly, many genes involved in photosynthesis were down-regulated.