The impact of CUP1 gene copy-number and XVI-VIII/XV-XVI translocations on copper and sulfte tolerance in vineyard Saccharomyces cerevisiae strain populations

In wine production, sulftes are widely used as antimicrobials and antioxidants, whereas copper is associated with fungicides and wine fning treatments. Therefore, wine yeasts are constantly exposed to these agents. Copper tolerance is related to the copy number of the CUP1 gene, encoding for a metallothionein involved in copper detoxifcation. In wine yeasts, sulfte resistance mainly depends on the presence of the translocation t(XVI;VIII) in the promoter region of the SSU1 gene. This gene encodes for a plasma membrane sulfte pump involved in sulfte metabolism and detoxifcation. Recently, a new translocation, t(XVI;VIII), was identifed. In this work, 253 Saccharomyces cerevisiae strains, representing three vineyard populations from two different continents, were analyzed, along with 20 industrial starters. Copper and sulftes tolerance as well as distribution of CUP1 gene copy-number, t(XVI;VIII)and t(XVI;XV) of SSU1 gene were studied to evaluate the impact of these genomic variations on population phenotypes. The CUP1 gene copy-number was found to be highly variable, ranging from zero to 79 per strain. Moreover it differently impacted the copper tolerance in the populations of the two continents. The diffusion of t(XVI;VIII) and, for the frst time, t(XVI;XV) was determined in the three vineyard populations. The correlation between the presence of the translocation and strain sulfte tolerance levels was signifcant only for the t(XVI;VIII).