Getting new biodiversity from a single strain: the story of 32 spores

The loss of biodiversity is becoming a common phenomenon in many different environments, including the winemaking one (Renouf et al., 2007). Several biological surveys for the discovering and the exploitation of the hidden oenological potential of the yeast biodiversity in our wine-producing regions are underway (Pretorius et al., 1999). Many intrinsic characteristics of peculiar strains can be selected and improved for such development protocols (Rodríguez et al., 2010). The auto-diploidization ability of natural homotallic strains is one of such properties that can be used in classical breeding projects on yeast spores, in order to obtain a population of homozygous at all loci individuals (Solieri et al., 2015). These strains can be screened for particular oenological traits and therefore selected for a wider application, not only in food related environments. The subsequent analysis of their genomes can link their prominent abilities to specific sequences, called Quantitative Trait Loci (QTL) (Steinmetz et al., 2002). In our study, 30 haploid genomes were obtained from a classical breeding project, after the sporulation of a Saccharomyces cerevisiae strain usually employed in our region in white winemaking. These genomes, together with the two of the parental strains, were sequenced using a shot-gun technology. The resulting reads were then assembled and the genomes of the spores were compared with the parental strains, in order to try to highlight the differences obtained with the breeding. The next step will be the annotation of these genomes, to assign all these differences to specific QTLs, linked to their oenological abilities.