Grapevine downy mildew dual epidemics: a leaf and inflorescence transcriptomics study

Grapevine downy mildew (DM) is one of the most important plagues affecting viticulture, especially in humid climates. The pathogen responsible of the disease, Plasmopara viticola, is able to differentially attack leaves and grapes and is currently controlled with a massive use of fungicides. Economical costs, adverse impact on environment and negative effects on human health have led to use resistant grapevine varieties. Nevertheless, cases of divergent dual epidemics underline that, in the same genotype, organs can vary in their susceptibility to DM. Grapevine genotypes exhibit a wide spectrum of resistance to DM, but little is known about the transcriptional basis behind dual epidemics. Based on a previous phenotypic screening under field and controlled conditions, we selected Cabernet Cortis which displays a different pattern of susceptibility to DM: mid-resistant leaves and mid-susceptible inflorescences. So far, we identified genes constitutively more highly or lowly expressed in Cabernet Cortis compared to Cabernet Sauvignon leaf and inflorescence.