Populational analysis of Saccharomyces cerevisiae strains from different appellations of origin and grape varieties by microsatellite analysis.

The objective of the present study was to evaluate populational relationships among Saccharomyces cerevisiae strains isolated from some of the Portuguese most important grapevine varieties in different appellations of origin, using polymorphic microsatellites. 
One hundred ninety two grape samples were collected during the 2006 and 2007 harvest season in the Vinho Verde (grape varieties: Arinto, Alvarinho, Avesso, Loureiro, Touriga Nacional) Bairrada (grape varieties: Arinto, Baga, Castelão Francês, Maria Gomes, Touriga Nacional) Alentejo (grape varieties, Aragonês, Trincadeira, Touriga Nacional), Terras do Sado (grape variety Castelão) Bucelas (grape variety Arinto) and Estremadura (grape varieties: Arinto, Aragonês, Castelão, Trincadeira, Touriga Nacional) appellations of origin. From the final stage of spontaneous fermentations, 2820 yeast isolates were obtained, mainly belonging to the species S. cerevisiae. An initial genetic screen, based on mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) and/or interdelta sequence analysis was followed by microsatellite analysis of strains with unique genetic profiles, using 10 highly polymorphic microsatellites. Our results showed that microsatellite analysis revealed a high resolution populational screen, showing that genetic differences and populational structures among S. cerevisiae populations derived from both “diagnostic” vineyard-, specific alleles and the accumulation of small allele-frequency differences across ten microsatellite loci. Heterozygosity was three to four times lower than the expected value, confirming the strong populational substructuring. The presented large-scale approach shows that each vineyard contains differentiated S. cerevisiae populations, showing the occurrence of specific native strains that can be associated with a terroir. 

Financially supported by the programs POCI 2010 (FEDER/FCT, POCTI/AGR/56102/2004) and AGRO (ENOSAFE, Nº 762).
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