ISOLATION AND CHARACTERIZATION OF NEW POLYMORPHIC SIMPLE SEQUENCE REPEAT LOCI IN GRAPE (VITIS-VINIFERA L)

Four new simple sequence repeat (SSR) loci (designated VVMD5, VVMD6, V VMD7, and VVMD8) were characterized in grape and analyzed by silver st aining in 77 cultivars of Vitis vinifera. Amplification products range d in size from 141 to 263 base pairs (bp). The number of alleles obser ved per locus ranged from 5 to 11 and the number of diploid genotypes per locus ranged from 13 to 27. At each locus at least 75% of the cult ivars were heterozygous. Alleles differing in length by only 1 bp coul d be distinguished by silver staining, and size estimates were within 1 or 2 bp, depending on the locus, of those obtained by fluorescence d etection at previously reported loci. Allele frequencies were generall y similar in wine grapes and table grapes, with some exceptions. Some alleles were found only in one of the two groups of cultivars. All 77 cultivars were distinguished by the four loci with the exception of fo ur wine grapes considered to be somatic variants of the same cultivar, 'Pinot noir', 'Pinot gris', 'Pinot blanc', and 'Meunier'; two table g rapes that are known to be synonymous, 'Keshmesh' and 'Thompson Seedle ss'; and three cable grapes, 'Dattier', 'Rhazaki Arhanon', and 'Markan di', the first two of which have been suggested to be synonymous. Alth ough the high polymorphism at grape SSR loci suggests that very few lo ci would theoretically be needed to separate all cultivars, the econom ic and legal significance of grape variety identification requires the increased resolution that can be provided by a larger number of loci. The ease with which SSR markers and data can be shared internationall y should encourage their broad use, which will in turn increase the po wer of these markers for both identification and genetic analysis of g rape.