USING SIMPLE SEQUENCE REPEATS (SSRS) FOR DNA-FINGERPRINTING GERMPLASMACCESSIONS OF GRAPE (VITIS L.) SPECIES

The USDA-ARS Vitis genetic resources collections in Geneva, N.Y., and Davis, Calif., contain approximate to 3600 accessions of >35 species. Accurate and unambiguous identification of these grapes is essential f or efficient and effective use of this germplasm. Previous workers hav e successfully used polymerase chain reaction (PCR)-generated SSRs to fingerprint cultivars of the wine and table grape species, V. vinifera . Building on this work, we conducted a test of five previously charac terized SSR loci on 110 accessions of 25 grape taxa (21 Vitis species and 4 hybrids) to determine if they would satisfy our need for identif ying cultivars within the USDA-ARS grape collections. Scorable SSR fra gments were produced with all 550 primer-accession combinations, with no null loci observed. The loci were highly polymorphic, with 16 to 38 different alleles found at a locus. Heterozygosity values ranged from 0.464 to 0.818, while gene diversity values ranged from 0.875 to 0.95 5. Discrimination power at a locus varied from a low of 0.947 to a hig h of 0.987. Combined discrimination power of all loci was effectively 1.000, with 2 chances in 100,000,000 that two sexually, independently derived grape accessions would not be distinguishable using this set o f five SSR loci. Two plants in the study that had previously been clas sified as belonging to different grape species were shown to have iden tical SSR fingerprints, showing that they almost certainly possessed t he same genotype. Because SSR markers are codominant and highly polymo rphic and SSR loci are generally conserved across a range of related s pecies, we strongly recommend SSRs for fingerprinting not only grape, but other clonal genetic resources collections as wed.