Grapevine genetic resources of Armenia: molecular fingerprinting and phylogenetic relationship among wild and cultivated grapevine

Abstract

Armenia is characterized by a high diversity of cultivated (Vitis vinifera L. subsp. Vinifera) and wild (Vitis vinifera L. subsp. sylvestris) grapes. The country has played a leading role in the centuries-lasting history of grapevine cultivation in the Near East. Varying climatic conditions and the existence of wild grapes lead to the formation and promotion of viticulture and winemaking, as evidenced by nearly 450 autochthonous varieties. Hundreds of unique indigenous cultivars are still preserved in old vineyards and abandoned gardens, though most of them are threatened by extinction. Wild grapes, thriving along riverbanks, climbing the rocks and embracing the trees can be found in Vayots Dzor, Tavush, Syunik provinces and in Artsakh. With the main goal to estimate the phylogenetic relationships among Armenian wild grapes and indigenous cultivars, and evaluating the possible contribution of wild grapes to the genetic makeup of indigenous cultivars, we analyzed 79 unique cultivars and 111 putative wild plants, collected from different viticulture regions, with 24 nSSR markers. The genetic diversity analysis conducted for wild grapes and indigenous cultivars unfolded the allelic richness of wild and cultivated gene pools and surprisingly for us revealed the absence of significant differences for all genetic parameters between the two subspecies. Moreover, the results registered for the number of different alleles (Na), effective number of alleles (Ne), and Shannon’s information index (I) have shown comparatively high values for wild grapes, while the observed negative value of Fixation index (F) for indigenous cultivars mirrored an abundance of heterozygote genotypes presuming random mating. The neighbour-joining (NJ) cluster analysis indicated a clear separation between the two subspecies vinifera and sylvestris and formed two main clusters. Applied non-hierarchical horizontal clustering using Structure software assigned the 190 genotypes into two clusters. The delta K criterion (ΔK) suggested K = 2 as the optimal uppermost hierarchical level of structure. Obtained results were comparable with the NJ cluster analysis and confirmed the divergence of sylvestris from vinifera, indicating a clear separation between the two subspecies. Meanwhile, results highlighted the role of gene flow between wild grapes and cultivars through observed overlaps and admixed ancestry values. Grapevine genetic resources of Armenia can contribute to overcoming biotic and abiotic stresses and better adaptation to climate change.