This project aims at improving our understanding of the molecular basis of the properties of S.cerevisiae industrial wine yeasts. These strains exhibit specific capacity to ferment under stressful conditions and metabolic properties quite different from their laboratory counterpart, on which have been focused most of the research in yeast genomic. The genetic basis of the phenotypic differences between the industrial and laboratory strains are unknown. It is assumed that sequence polymorphisms determine such phenotypic variations. This project aims at identifying the sequence polymorphisms involved in the specific properties of these strains with a focus on the contribution of gene expression variation on these phenotypes. This project is positioned in the dynamic of a research field that aims at improving the understanding of the molecular basis of the intraspecific biodiversity in Saccharomyces sp. The achievement of this project will be based on the integration of three types of approaches, two of 'genetical genomic' which will aim at identifying simultaneously QTL involved in technological traits and in gene expression variation at the transcriptome scale, combined with an analysis of the genome sequence of an industrial yeast strain. The parallel search for QTL involved in expression variation and of those responsible of fermentation phenotypes should facilitate the identification of genes involved in technological traits. Moreover, the identification of expression QTL should open new possibilities to decipher the regulatory network variations underlying the expression variations and their potential impact in the yeast phenotypes. The project will be associated to a in depth analysis of the genome sequence of an industrioal yeast which is now available. This should permit an exploration of the relationship between structural polymorphisms and expression variation, at the genome scale. Given that yeast is an highly tractable micro-organism, a functional demonstration of the role of candidate genes should be obtained. This work represents therefore a significant aspect of the functional analysis of this new genome. The knowledge on both the function of the genes affected and the molecular mechanisms involved, should offer a global view on the adaptation of these yeast to stressful environments. This work should provide the frame for future general studies on the relation between genetic variation and phenotypic variation in these strains. The identification of key genes of the strains properties will have applied interest in relation with the opportunities opened in strain improvement.