| Summary: | <p>Abstract</p> <p>Background</p> <p>Interspecific hybrids between <it>S. cerevisiae</it> × <it>S. kudriavzevii</it> have frequently been detected in wine and beer fermentations. Significant physiological differences among parental and hybrid strains under different stress conditions have been evidenced. In this study, we used comparative genome hybridization analysis to evaluate the genome composition of different <it>S. cerevisiae</it> × <it>S. kudriavzevii</it> natural hybrids isolated from wine and beer fermentations to infer their evolutionary origins and to figure out the potential role of common <it>S. kudriavzevii</it> gene fraction present in these hybrids.</p> <p>Results</p> <p>Comparative genomic hybridization (CGH) and ploidy analyses carried out in this study confirmed the presence of individual and differential chromosomal composition patterns for most <it>S. cerevisiae</it> × <it>S. kudriavzevii</it> hybrids from beer and wine. All hybrids share a common set of depleted <it>S. cerevisiae</it> genes, which also are depleted or absent in the wine strains studied so far, and the presence a common set of <it>S. kudriavzevii</it> genes, which may be associated with their capability to grow at low temperatures. Finally, a maximum parsimony analysis of chromosomal rearrangement events, occurred in the hybrid genomes, indicated the presence of two main groups of wine hybrids and different divergent lineages of brewing strains.</p> <p>Conclusion</p> <p>Our data suggest that wine and beer <it>S. cerevisiae</it> × <it>S. kudriavzevii</it> hybrids have been originated by different rare-mating events involving a diploid wine <it>S. cerevisiae</it> and a haploid or diploid European <it>S. kudriavzevii</it> strains. Hybrids maintain several <it>S. kudriavzevii</it> genes involved in cold adaptation as well as those related to <it>S. kudriavzevii</it> mitochondrial functions<it>.</it></p>
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