Molecular survey of Georgian traditional grapevine genetic resources

Corresponding author: serena.imazio@unimi.it

International audience

English. The South Caucasus area is considered one of the main centers of origin and domestication for the cultivated grapevine V. vinifera L. sativa. The aim of this work is to study the genetic structure of Georgian grapevines by analyzing 135 Georgian grapevine accessions using 20 SSR molecular markers and to verify the contribution of Georgian germplasm to the European viticulture. Among the 135 selected samples 112 are representatives of the traditional wine making Georgian varieties and 23 were collected from several Georgian woodlands and, after visual inspection, were considered representatives of Vitis vinifera sylvestris subspecies. Molecular fingerprints (20 SSR loci) of all the 135 accessions were compared with data from the 2300 accessions conserved at the Institut National de la Recherche Agronomique (INRA) grape germplasm repository of Domaine de Vassal. Nei’s genetic distance was calculated among the Vassal and Georgian samples and a dendrogram was built to verify the presence of synonyms and to have an overview of the structure of Georgian grapevine germplasm compared with the ones belonging to other countries. Results highlighted that most of Georgian viticulture is quite isolated from elsewhere. These results seem to confirm that the Georgian typical varieties didn’t spread to other European countries and, on the other hand Georgian viticulture did not have gene flow from elsewhere. To verify the existence of parent-offspring relationships, the software MLrelate and Famoz were used to analyze the dataset (Domaine de Vassal and Georgian accessions). Interesting relationships were identified especially between Georgian samples and among Georgian and neighbor countries. The apparent isolation of Georgian germplasm makes this viticulture particularly interesting to be investigated, and for this reason we used Identity and Microsat software to describe the structure of these samples and to perform a study on allele frequencies and characterization. The results suggest that the Georgian viticulture is still strongly correlated to its geographic origin, allowing us to clearly distinguish groups of accessions belonging to different regions of the country. In the wild samples, the molecular fingerprint has revealed very few mistakes or inter-specific crossings in the pool of collected samples and highlighted that, as already verified for other regions, there is diversification among the wild and cultivated compartments, even if this separation doesn’t seem to be, in the Georgian case, as robust as seen in other viticultural areas.