The SSR-based molecular profile of 1005 grapevine (Vitis vinifera L.) accessions uncovers new synonymy and parentages, and reveals a large admixture among varieties of different geographic origin

A collection of 1005 grapevine accessions was genotyped at 34 microsatellite loci (SSR) with the aim of analysing genetic diversity and exploring parentages. The comparison of molecular profiles revealed 200 groups of synonymy. The removal of perfect synonyms reduced the database to 745 unique genotypes, on which population genetic parameters were calculated. The analysis of kinship uncovered 74 complete pedigrees, with both parents identified. Many of these parentages were not previously known and are of considerable historical interest, e.g. Chenin blanc (Sauvignon x Traminer rot), CovS (Harslevelu selfed), Incrocio Manzoni 2-14 and 2-15 (Cabernet franc x Prosecco), Lagrein (Schiava gentile x Teroldego), Malvasia nera of Bolzano (Perera x Schiava gentile), Manzoni moscato (Raboso veronese x Moscato d'Amburgo), Moscato violetto (Moscato bianco x Duraguzza), Muscat of Alexandria (Muscat blanc A petit grain x Axina de tres bias) and others. Statistical robustness of unexpected pedigrees was reinforced with the analysis of an additional 7-30 SSRs. Grouping the accessions by profile resulted in a weak correlation with their geographical origin and/or current area of cultivation, revealing a large admixture of local varieties with those most widely cultivated, as a result of ancient commerce and population flow. The SSRs with tri- to penta-nucleotide repeats adopted for the present study showed a great capacity for discriminating amongst accessions, with probabilities of identity by chance as low as 1.45 x 10(-27) and 9.35 x 10(-12) for unrelated and full sib individuals, respectively. A database of allele frequencies and SSR profiles of 32 reference cultivars are provided.