Wild Grapevine (Vitis vinifera L. subsp. sylvestris (Gmelin) Hegi) in Italy: Distribution and Preliminary Genetic Analysis

Vitis vinifera L. ssp. sylvestris grows principally in well preserved natural habitats. Its survival is threatened mainly by human land use practices. In spite of its importance as a progenitor of cultivated forms, very little research has been devoted to the study of its distribution and genetic structure. During the period 2007-2009 a census was carried out in 9 of the 20 Italian regions with major intensification in 4 of them. Eight hundred and twenty plants corresponding to 165 sites were found. Over 50% of these were localized in two regions only. After collection of the wooden material for greenhouse propagation and after rooting of the cuttings, samples were taken to perform genetic analysis using 10 nuclear SSR markers. Some genetic parameters (Ne, Ho, He, Fis, Fst and I) were calculated on the allelic size, grouping plants once for locus and once for region of origin. The results showed Italian wild grapevine expressed altogether high biodiversity and low rate of isolation. In particular plants from Sicilia, in spite of their low number, stood out for their high heterozigosity and low inbreeding and isolation level. This particularity brought the same plants to have the high genetic distance in the NJ phylogenetic tree. PCA analysis separated in 2 well-defined groups along the first component without correspondence with geographical grouping. AMOVA analysis confirmed that the highest variance was placed within populations (only 5% of the overall variance was placed among populations). SSR marker analysis is still in progress to verify the existence of introgression among wild and cultivated compartments and to comprehend the extent of factors driving the genetic structure and the possible pattern of dissemination of wild grapevine in Italy.