Genetic diversity and relationships of Vitis vinifera L. in the south caucasus

The South Caucasus is recognized as one of the primary centres of grapevine domestication and harbours an extraordinary wealth of wild and cultivated grapevine diversity. Understanding the genetic structure and relationships of this germplasm is essential both for conservation and for the valorisation of local varieties in viticulture, wine making and breeding. The objectives of the present study consisted of the exploration of grape genetic diversity and the investigation of genetic relationships existing in Armenia, Azerbaijan and Georgia. Germplasm studied included 425 non-redundant accessions, genotyped using 24 nSSR-markers, from these three countries and from Western to Eastern Europe. The total sample set included 366 Vitis vinifera subsp. sativa varieties, 50 Vitis vinifera subsp. sylvestris individuals and 9 interspecific crosses. A Bayesian clustering analysis and diversity parameters revealed that Armenia and Azerbaijan share a common gene pool, whereas the Georgian gene pool is mainly independent, with few intermixes. First-order parentage analysis identified 208 first-degree relationships with 196 grape varieties (46%) being involved, while 231 genotypes (54%), respectively 180 (42%) sativa and 51 (12%) sylvestris did not show any genetic relatedness. Two reconstructed genetic profiles are proposed, suggesting that these are likely key ancestors within the Georgian gene pool. This treasure of genetic diversity from one of the cradles of wine culture holds immense potential for research and breeding with an unique cultural-historical background. Therefore, further surveys and research are essential for the conservation, sustainable management, and utilization of the grapevine genetic biodiversity of the South Caucasus.