Résumé
What drives the diversity of S. cerevisiae yeast strains that accomplish wine fermentation?Recent genetic and genomic studies have shown that wine strains clustered in a specific population adapted to the wine environment, but we need to better know the genetic bases of a better fitness in the wine environment.In order to understand how yeast adapted to the wine environment we built 3 x 4 recombinant populations containing either wine strains, Mediterranean oak strains (as a grape must naive population), and strains from both origins. These three populations were grown for 24 serial fermentations in a typical Sauvignon grape must. Such an experimental evolution led to an improvement of the fitness of the recombinant Mediterranean oak/ wine populations. Several changes in the frequencies of allelic variations could be observed in specific regions , such as for SSU1 and ECM34 involved in sulfite resistance or MET10 involved in sulfide reduction, as well as other regions. This shows that adaptation to the wine environment involves multiple regions. This adaptation may also have unexpected consequences. Indeed H2S production varies according to the origin of the yeast population. Interestingly, we found that the amplification of the CUP1 genes impacts the activity of the sulfur assimilation pathway, and provides an interesting example.Nevertheless, the wine ecosystem contains at least two compartments : cellars and vineyards. Looking for the evolution of wine yeasts raise the questions of the connection between these two. The measures of gene flow between these two compartments, indicate that they are indeed connected, but the identification of the main vectors remain a central question and the role of insects has to be better explored.