Résumé
Saccharomyces cerevisiae’s requirement of reduced sulfur to synthesize methionine and cysteine during alcoholic fermentation, is mainly fulfilled through the sulfur assimilation pathway. In this pathway, S. cerevisiae reduces sulfate into sulfur dioxide (SO2) and sulfide (H2S), whose overproduction is a major issue in winemaking due to its negative impact on wine aroma. The amount of H2S produced is highly strain-specific and depends as well on the SO2 concentration, often added to the grape must. Applying a Bulk Segregant Analysis to a 96 strain-progeny derived from two strains with different ability to produce H₂S we decipher new genetic bases of the H2S production in the presence of SO2. The comparison of the allelic frequencies along the genome of pools of segregants producing a small or a high quantity of H₂S during alcoholic fermentation pointed out to two regions (QTL) involved in the variations of H₂S production. The functional analysis of genes in the first region led to the discovery of the role of ZWF1, while in the second region, variants of genes previously not known for their impact on sulfur metabolism were found. This data represents a novel insight into the regulation of H₂S production during wine fermentation and offers a fresh perspective on the interplay between the sulfur assimilation pathway and cell metabolism.