Microsatellite analysis of Saccharomyces uvarum diversity

Considered as a sister species of Saccharomyces cerevisiae, Saccharomyces uvarum is, to a lesser extent, an interesting species for fundamental and applied research studies. Despite its potential interest as a new gene pool for fermenting agents, the intraspecific molecular genetic diversity of this species is still poorly investigated. In this study, we report the use of 9 microsatellite markers to describe S. uvarum genetic diversity and population structure among 108 isolates from various geographical and substrate origins (wine, cider, natural sources). Our combined microsatellite markers set allowed differentiating 89 genotypes. In contrast to S. cerevisiae genetic diversity, wild and human origin isolates were intertwined. Seventy five % of strains were proven to be homozygotes and estimated heterozygosity suggests a selfing rate above 0.95 for the different population tested here. From this point of view, the S. uvarum life cycle appears to be more closely related to S. paradoxus or S. cerevisiae of natural resources than S. cerevisiae wine isolates. Population structure could not be correlated to distinct geographic or technological origins suggesting lower differentiation that may result from a large exchange between human and natural populations mediated by insects or human activities