Genetic insights into Georgian grapevine germplasm

Abstract

The South Caucasus is widely recognized as a primary center of grapevine domestication (Vitis vinifera L.). Genetic studies highlight the singularity and uniqueness of the Georgian grapevine genetic pool, characterized by varieties exhibiting exceptional phenotypic diversity across important traits related to crop yield, grape quality, and resistance to a range of biotic and abiotic factors. Recognizing their significance, we have characterized the genetic resources preserved at the National Grapevine Collection of the SRCAat Jighaura (GEO 038), the largest grapevine collection in Georgia. The systematic genetic profiling of 782 accessions of putative Georgian origin at 13 SSR and 240 SNP loci differentiated 319 unique genetic profiles, with 162 preserved twice or more in the Collection, some as misnamed accessions or under local synonyms. Among the 319 differentiated genotypes, 160 were found to match the grapevine genetic profiles stored in international databases, most of them of alleged varieties of Caucasian origin. This is the case of the Georgian varieties ‘Chinuri’, ‘Argvetula Sapere’, and ‘Tkupkvirta’, which were the most frequently identified genotypes in the Collection, in 19, 14 and 13 accessions, respectively. On the other hand, 159 of the genetic profiles differentiated in this study were not found in the bibliography, so they could be useful for the identification and management of these putative local varieties.

The integration of genetic and phenotypic data revealed some somatic variants, further contributing to intra-varietal diversity and offering potential for varietal innovation. Additional genetic analyses confirmed the clear differentiation of Georgian germplasm from European varieties previously reported, and revealed a major subdivision of local varieties into two genetic groups, likely reflecting contrasting environmental and orographic conditions between western and eastern Georgia. The study of parentage relationships revealed a large number of first-order kinship relationships, some of them not previously reported. Altogether, this work provides a significant contribution to the current knowledge of the Georgian germplasm. This information is useful to address questions regarding grapevine domestication and diversification processes, and its singularity can be harnessed to enhance both oenological and key agronomic traits, essential to face current viticultural challenges.

Acknowledgements

This work was supported by project GCP/GEO//EC “FAO support to Georgian agricultural sector under ENPARD III”. JT acknowledges funding from the Ramón y Cajal Programme (RYC2022-037758-I), supported by MCIU/AEI/10.13039/501100011033 and the European Social Fund Plus (ESF+).