The use of simple sequence repeat (SSR) and amplification fragment length polymorphism (AFLP) markers for analysis of interrelationships and origins of wine grape cultivars

A system was developed using simple sequence repeats (SSRs) to uniquely identify winegrape cultivars (Vitis vinifera L.). DNA was extracted from 132 winegrape accessions representing 55 different cultivars. Eighteen new SSR markers were developed and characterized with these cultivars along with 7 SSR markers developed by Thomas and Scott (1983). From 2 to 14 alleles were detected at each SSR locus. These 25 SSR loci are, in combination, likely to provide unique fingerprints for all grapevine cultivars. Sixty-two accessions were analyzed using Amplified Fragment Length Polymorphisms (AFLPs) and this method also proved to be capable of effectively fingerprinting grapevine cultivars. SSRs, however, are superior for cultivar identification because results can be readily compared between experiments. In an attempt to detect clonal differences, clones of several cultivars were compared with both SSR and AFLP markers. A single clonal difference was detected with one SSR marker that distinguished one clone (#16) of Chardonnay from the other 14 clones. Clonal differences were not detected with AFLPs or with an AFLP variant that employed methylation-sensitive restriction enzymes. The origins of most winegrapes are unknown but are of both academic and practical interest. The parents of the classic winegrape cultivar 'Cabernet Sauvignon' were determined to be 'Sauvignon Blanc' and 'Cabernet Franc'. This is the first determination of the origin of a classic wine grape cultivar. The parentages of 'Durif' and 'Burger' were also discovered, and a single parent could be proposed for many other major winegrapes.