Section: New Results

Genetic Determinisms of Aborted Fermentation in Winemaking

This study contributes to the understanding of the mechanisms leading to stuck fermentation in winemaking, an economic prejudice [7]. A number of factors can trigger stuck or aborted fermentation such as high temperature, high ethanol concentration, low pH. The biodiversity of natural yeast strains used in winemaking starters has as a consequence that some of them are more prone to abort fermentation than others, indicating a genetic determinism. Crosses between strains called “sensitive” or “resistant” to stuck fermentation occurrence, followed by back-crosses with the “sensitive” parent while selecting for the “resistant” phenotype, allowed us to reduce the amount of genetic material inherited from the “resistant” parent in the progeny, ending to 3 small introgression areas after 4 generations. Quantitative Trait Locus (QTL) detection in this progeny (77 strains) involved characterization of SNP inheritence (circa 1200 validated SNPs) from either parent, through micro-array hybridization, mapping of the SNP on the reference genome and phenotypic measurements on the progeny. This analysis made it possible to detect two genes which, when inactivated by naturally occurring mutations, act as major perturbators of several fermentation parameters in winemaking physiological conditions. Consequently, our industrial partner incorporated into its catalogue of winemaking starters, strains carrying the functional forms of these genes.