Tandem repeat-tRNA (TRtRNA) PCR method for the molecular typing of non-Saccharomyces subspecies.

There is a worldwide trend to understand the impact of non-Saccharomyces yeast species on the process of winemaking. Although the predominant species at the end of the fermentation is Saccharomyces cerevisiae, several non-Saccharomyces species present during the first days of the process can produce and/or release aromas that improve the bouquet and complexity of the final wine. Since no genomic sequences are available for the predominant non-Saccharomyces species selected from grapes or musts (Hanseniaspora uvarum, Hanseniaspora vineae, Hanseniaspora opuntiae, Metschnikowia pulcherrima, Candida zemplinina), a reproducible PCR method was devised to discriminate strains at the subspecies level. The method combines different oligonucleotides based on tandem repeats with a second oligonucleotide based on a conserved tRNA region, specific for ascomycetes. Tandem repeats are randomly dispersed in all eukaryotic genomes and tRNA genes are conserved and present in several copies in different chromosomes. As an example, the method was applied to discriminate native M. pulcherrima strains but it could be extended to differentiate strains from other non-Saccharomyces species. The biodiversity of species and strains found in the grape ecosystem is a potential source of new enzymes, fungicides and/or novel sustainable methods for biological control of phytopathogens.