Genetic diversity of Vitis vinifera in Georgia: relationships between local cultivars and wild grapevine, V-vinifera L. subsp sylvestris

The Caucasus and Middle East regions are considered to be the primary centre of origin of cultivated grapevine, and, as confirmed by archaeobotanical, archaeological, and cultural evidence, Georgia belongs to this earliest centre of winemaking. This study aims to investigate the genetic diversity, population structure and relationships of local autochthonous wine cultivars and wild grapevine, Vitis vinifera subsp. sylvestris. Multiple accessions of 15 Georgian aboriginal cultivars and 42 individuals of wild grapevine from different regions of Georgia and adjacent Turkey were genotyped at 17 nuclear microsatellite loci. A total of 160 alleles were detected with a mean number of 9.41 alleles and the effective number of 4.6 alleles (r) per locus, indicating that the SSRs were highly informative. Despite high genetic diversity, the level of genetic differentiation among defined wild and cultivated populations is low (F (st) = 0,05; P***), which together with the outcome of model-based cluster analyses and genetic assignment methods point to gene flow among wild populations, as well as among cultivated and wild accessions. Besides, the data presented here suggest that local cultivars 'Saperavi' and 'Tavkveri' are independently derived from different local wild populations, while the majority of Georgian cultivars seem to have a single origin. Overall, the present study takes important steps for better characterization of Georgian cultivated and wild grapevines, and supports Georgia as one of the important centres of grapevine domestication still harbouring valuable genetic resources for grapevine breeding.