Sclerotinia sclerotiorum is a worldwide plant pathogenic fungus that causes important diseases (known as white mold, Sclerotinia stem rot, wilt or stalk rot, or Sclerotinia head rot) 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 (dry edible beans, soybean, peas, lentils, alfalfa, potato, peanut, mustard, safflower, flax, lettuce, carrots, etc.). Interestingly, the model plant Arabidopsis thaliana has been shown to be naturally infected by S. sclerotiorum (A.R. Wang et al. 2008), thus opening the way to basic studies. The main aims of this project are:

(1) The identification and functional analysis of genes involved in Sclerotinia resistance in oilseed crops, mainly Brassicaceae (oilseed rape, canola) and Arabidopsis as a model organism.

(2) The exploration of genetic resources in Brassica (B. 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 (OSR) 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 of the main signalling pathways controlling Arabidopsis defence responses to Sclerotinia and (iii) identify some essential components (NO, ROS) required for plant resistance to S. sclerotiorum. Finally, the analysis in oilseed rape of different defense marker genes (previously analyzed in Arabidopsis) indicates that their regulation is largely conserved in response to S. sclerotiorum infection in this crop.

This project will contribute to the identification of the molecular and genetic basis of quantitative resistance to S. sclerotiorum in the crop species B. napus and in the model plant species A. thaliana. 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.