Final Report Summary - VARIWHIM (Understanding White Mold disease quantitative resistance using natural variation)
Crop losses due to pathogen attacks are a major limitation to yield and a serious threat to food security worldwide. As opposed to host-specialists, generalist parasites have the ability to infect a wide range of plant species in nature. These parasites are among the most devastating plant pathogens and on the rise, yet our knowledge on the molecular bases of infection by generalists remains limited. The ERC project VariWhim aims at providing a global understanding of the complex interactions between plants and generalist fungal pathogens such as Sclerotinia sclerotiorum, through integrated approaches considering both the plant and fungal partners. Using genome wide association and reverse genetics in Arabidopsis thaliana, we revealed several molecular players of the plant quantitative disease resistance. Our findings points towards an important role of pleiotropic genes and gene expression variation in the evolution of the resistant phenotype. The project provided new insights into the strategy used by the fungus to colonize its hosts, and how evolution shaped the genome of this destructive pathogen. We provided evidence for host-specific virulence mechanisms as well as universal mechanisms enhancing the colonization of diverse host plants. Overall our results represent a major leap forward in our understanding of plant interactions with broad host range pathogens emphasizing molecular properties emerging at the genome level that could be targeted in novel disease management strategies.