Study of genetic diversity in V. vinifera subsp. sylvestris in Azerbaijan and Georgia and relationship with species of the cultivated compartment

Vitis vinifera subsp. sylvestris is the wild progenitor of cultivated grapevine (V. vinifera subsp. sativa). Wild grapevine populations are part of the Eurasian flora, from Central Asia to the Mediterranean Basin. In most countries, the wild grapevine is considered on the brink of extinction and for this reason several research projects around the world - and particularly in Europe - are aimed to study the genetic diversity of wild grapevines in order to set up a germplasm collection. The recovery and characterization of wild grapevine genetic resources in the Caucasian region, which is considered to be the birth place for viticulture, is one of the main goals of the COST Action FA1003 European project. In the frame of this project, wild grapevine samples collected in Azerbaijan and Georgia were analysed with nine SSR molecular markers. From these molecular data, the genetic relationship of this wild material with local cultivars as well as the wild and cultivated compartments of European germplasm were evaluated. The SSR allelic patterns were analysed with GenAlEx 4.2 software to investigate the genetic diversity and STRUCTURE 3.2 software to investigate the admixture proportions among germplasms. By PCoA (Principal Coordinates Analysis) of which the two first coordinates accounted for about 50% of total variability, genotypes were classified in two main groups: i) European and Georgian germplasm; ii) Azerbaijani germplasm. STRUCTURE analysis revealed clearly the diversity of European germplasm in respect to the Caucasian germplasm. In conclusion, the analysis of genetic relationships in our dataset provided evidence of gene flow between wild and cultivated genotypes in the Caucasian germplasm.