The team has studied in particular biological invasions of pathogenic fungi which lead to new emergent diseases. Our work on biological invasions was at the forefront of research, showing that biological invasions can redistribute the genetic diversity from the area of origin and allow hybridizations between populations previously isolated, creating new genotypes and fostering rapid adaptation. Invasions of pathogenic fungi however can occur successfully starting from a very low number of genotypes while causing serious emerging diseases on natural ecosystems or crops. The team studied in particular of the castrating anther-smut on Caryophyllaceae, the invasions of the grapevine downy mildew (in collaboration with INRA Bordeaux, F. Delmotte), and of the oilseed rape pathogen Leptosphaeria maculans (in collaboration with INRA Bioger, T. Rouxel), by using genetic markers and sophisticated methods of population genetics, making it possible to test evolutionary scenarios. For the grapevine downy mildew, we showed that its introduction in Europe from the United States at the beginning of the 20th century had resulted, by a ‘leap-frog’ event, in two differentiated populations in Europe, separating Western and Eastern Europe, because of reduced commercial and human exchanges. For the castrating anther-smut fungus Microbotryum lychnidis-dioicae, the team showed that the invasion of the disease in the United States on the white campion at the beginning of the 20th century could be successfully achieved by the introduction of only 2 individuals from Scotland. These studies thus overall contributed to a better understanding of how invasions by pathogens can occur, which has important applied consequences in agriculture but also for the maintenance of the balance of natural ecosystems in the face of global changes.
