Sclerotinia sclerotiorum is a worldwide plant pathogenic fungus that causes important disease on a wide variety of broadleaf crops. It is commonly found damaging oilseed crops, (oilseed rape and sunflower) but causes disease on many other crops including vegetables. Interestingly, the model plant Arabidopsis thaliana has been shown to be naturally infected by S. sclerotiorum, thus opening the way to basic studies. The main aims of this project are: (i) identification and functional analysis of genes involved in Sclerotinia resistance in oilseed crops, mainly Brassicaceae (oilseed rape, canola) and Arabidopsis as a model organism, (ii) exploration of the genetic resources in Brassica (Brassica napus and related species B. rapa and B. oleracea) in order to create a panel for genetic association studies and establish a major resource for the study of oilseed rape resistance to Sclerotinia. Some candidate genes for Sclerotinia resistance were already identified in oilseed rape in the frame of the National Sclerotinia Initiative funded by USDA – ARS (Zhao et al, 2007) and of the ANR Génoplante project (L. Perchepied et al, 2010). These recent analyses allowed us to (i) reveal an unexpectedly large variation of resistance/susceptibility in Arabidopsis, (ii) investigate the contribution to Sclerotinia resistance of the main signaling pathways controlling oilseed rape and Arabidopsis defense responses and (iii) identify some essential components required for plant resistance to S. sclerotiorum. This project will contribute to the identification of the molecular and genetic basis of quantitative resistance in the crop species B. napus and in the model plant species Arabidopsis thaliana to S. sclerotiorum. It will generate useful molecular markers for Sclerotinia resistance breeding programs. An interdisciplinary strategy will be adopted combining genomics, population genetics, and functional validation approaches, in order to successfully complete the aims of this project. In WP1, mapping of quantitative resistance loci in a large collection of Arabidopsis accessions in response to Sclerotinia will be undertaken. In a second step of the project (WP2), polymorphism of candidate gene sequences will be identified and analyzed in oilseed rape for validation by genetic association. Genotyping on selected SNP will then be done, using Illumina technology, on diversity panels evaluated for Sclerotinia resistance within the project. In parallel to this genomic approach, genetic resources will be explored in Brassica (WP3) (B. napus and related species) and used to create panels (winter and spring types) for further genetic association. Finally in a last project step (WP4), genetic association studies will be performed by studying the relation between candidate gene sequence polymorphisms and phenotypic data generated on diversity panels, in order to develop useful molecular markers for Sclerotinia resistance breeding programs