In addition to Saccharomyces cerevisiae, the cryotolerant yeast species S. uvarum is also used for wine and cider fermentation but nothing is known about its natural history. Here we use a population genomics approach to investigate its global phylogeography and domestication fingerprints using a collection of isolates obtained from fermented beverages and from natural environments on five continents. South American isolates contain more genetic diversity than that found in the Northern Hemisphere. Moreover, coalescence analyses suggest that a Patagonian sub-population gave rise to the Holarctic population through a recent bottleneck. Holarctic strains display multiple introgressions from other Saccharomyces species, those from S. eubayanus being prevalent in European strains associated with human-driven fermentations. These introgressions are absent in the large majority of wild strains and gene ontology analyses indicate that several gene categories relevant for wine fermentation are overrepresented. Such findings constitute a first indication of domestication in S. uvarum.

Polyploidy is a major evolutionary process in eukaryotes—particularly in plants and, to a less extent, in animals, wherein several past and recent whole-genome duplication events have been described. Surprisingly, the incidence of polyploidy in other eukaryote kingdoms, particularly within fungi, remained largely disregarded by the scientific community working on the evolutionary consequences of polyploidy. Recent studies have significantly increased our knowledge of the occurrence and evolutionary significance of fungal polyploidy. The ecological, structural and functional consequences of polyploidy in fungi are reviewed here and compared with the knowledge acquired with conventional plant and animal models. In particular, the genus Saccharomyces emerges as a relevant model for polyploid studies, in addition to plant and animal models.

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In agricultural sciences, breeding strategies have historically been used to select new, optimized plant varieties or animal breeds. Similar strategies are possible for genetic improvement of wine yeasts. We optimized 11 relevant enological traits in a single clone using successive hybridization and segregation steps. A hybrid obtained by crossing two parent strains derived from commercial wine yeasts showed that some of the traits were readily optimized. Dominance/recessivity, heterosis and transgression were observed among 51 segregating progeny. On the basis of this information, all the optimal characters from both parents were combined in a single strain following two targeted sexual crosses. This article presents a powerful methodology for obtaining a single wine strain with numerous fermentative qualities that does not produce off-flavors.