Grapevine (Vitis vinifera L.) Germplasm from Siena (Italy) Includes Rare Strains and Reveals Population Structuring

Molecular characterization was carried out on samples of historical grapevine populations that were gathered from within and around the medieval walls of Siena. Forty-nine grapevines were selected based on their age, historical site of growth, grapevines’ ampelography, and for being relict accessions, obsolete to cultivation. SSR profiling data were compared to 44 known grapevines, revealing six functional genetic groups with significant similarity to grapevine types generally grown in Tuscany. The Sienese germplasm is enriched with rare grapevines at risk of extinction, such as Zuccaccio, Gorgottesco, Tenerone, Prugnolo gentile, Occhio di Pernice, Procanico, Rossone, Mammolo, and Canina. Population genetics analysis revealed the existence of five subpopulations structure (-k5) in analogy with cluster analysis.