Geographic Origin and Diversity of Wine Strains of Saccharomyces

The availability of genome sequence information from a large collection of strains of Saccharomyces isolated from a variety of geographic regions and ecological niches has enabled a detailed analysis of genome composition and phenotype evolution, the two components of strain diversity. These analyses have also provided a relatively complete depiction of the origins of wine strains. In population genomic analysis, wine strains of S. cerevisiae cluster as a highly related group, but one that shows a greater level of phenotypic differentiation than would be predicted based on the level of genomic similarity. Natural and human selection and genetic drift have played roles in the evolution of wine strain diversity. Phenotypic diversity is so extensive that no one strain accurately represents all wine strains with respect to biological properties and fermentation performance. In addition, both commercial and native isolates have been found to carry introgressions, regions of DNA derived from nonhomologous organisms, suggestive of cell fusion events with yeast of different genera and species. Comparative sequence analysis has thus refined our knowledge of yeast lineages and offers explanation for the evolution of phenotypic diversity observed in winery and vineyard populations.