Mitochondrial DNA transmission in Saccharomyces sensu stricto hybrids constructed by spore conjugation.

The Saccharomyes sensu stricto group contains the most important species for the Fermentation Industry. Interspecifichybridisation among these yeasts is a useful tool for obtaining starter cultures with improved fermentative traits. Several S.cerevisiae x S. uvarum hybrids have been constructed and successfully employed in wine fermentations. Studies demonstratedthat they inherit mtDNA from either parental species. Recently, however, the interest for using other Saccharomyces species inoenology has been growing and the prospective of constructing hybrids with other species is being explored. We investigated theinheritance of mtDNA in hybrids constructed by spore conjugation between S. cerevisiae and other Saccharomyces sensu strictospecies. We obtained three hybrids for each type of crossing: S. cerevisiae x S. cariocanus; S. cerevisiae x S. mikatae; S.cerevisiae x S. kudriavzevii; S. cerevisiae x S. paradoxus; S. cerevisiae x S. uvarum. By analysing the RFLP of the mtDNA andsequencing COXII gene we observed that: 1) in all the Saccharomyces hybrids mtDNA is inherited by only one of the parentalstrains; 2) the parental strain transmitting the mtDNA can belong to either parental species; 3) for each combination of parentalstrains the same type of mtDNA is always inherited. These findings suggest that mtDNA is not inherited accidentally and thisinformation can be exploited when constructing starter cultures by interspecific hybridisation.