Biodiversity and conservation of Vitis vinifera ssp. sylvestris

The distribution of Vitis vinifera subsp. sylvestris, the wild grapevine subspecies of Vitis vinifera L., has been dramatically reduced in its major sites of diffusion, at first by the spread, over the last 150 years, of pathogens from North America and, more recently, with fragmentation of habitat and disbranching by humans. For these reasons, in this work, 418 wild grapevine samples, belonging to 78 populations, were collected in their main Mediterranean distribution areas, including the Caucasus area, and the extent of their genetic variability evaluated by analysing nuclear and plastid microsatellite DNA polymorphism. Results evince low haplotype diversity value, with five haplotypes detected within the analysed populations. The highest within-population haplotypic diversity, with the presence of all five detected haplotypes, was found in the Caucasus regions and in the central regions of Italy. The distribution of all detected haplotypes suggests the Caucasian region as the possible centre of origin of Vitis vinifera ssp. sylvestris. A principal plastid lineage was found to be fixed in several locations, in the northernmost European countries and in the southern island of Sardinia. Nuclear SSR results revealed the existence of three main areas where wild grapevine is still present and maintains a good level of genetic diversity. These results draw the attention to two different refugium sites in the in Mediterranean basin and suggest that conservation priority should be given to grapevine populations still preserved in hotspots of these regions.