Genetic Comparison of Greek Cultivars of Vitis vinifera L. by Nuclear Microsatellite Profiling

Abstract

We have initiated the characterization of the Greek genetic resources of Vitis vinifera L. through microsatellite profiling, with the aim of providing accurate identification of Greek cultivars and compiling the molecular data together with available ampelographic information in the form of a web-based database. This work reports microsatellite profiling results obtained on 50 Greek grapevine cultivars, including major wine and table grape cultivars, at 11 microsatellite (SSR; simple sequence repeats) loci. The choice of nine previously characterized SSR markers, which have been used in other European studies, makes our results comparable at these loci to those of other laboratories and will contribute to the ongoing international effort of genotype identification. Furthermore, 6 out of the 11 SSR markers used are subject to an international investigation in order to assay their usefulness as descriptors. The 11 SSR markers used in this study proved to be informative, with a total number of 87 alleles and a mean of 7.9 alleles per locus. The observed heterozygosity at each locus ranged from 0.68 to 0.96. The cumulative probability of identity (PI) between two cultivars by using these 11 markers was 2.218 x 10^-10, corresponding to the statistical potential to distinguish 94,000 unrelated cultivars. This cumulative PI was lower than reported in previous studies using a slightly different set of markers. Three pairs of synonyms were found. Further genotyping at six more loci confirmed synonymy in two cases (Fileri Mantineias and Moschofilero; Moschato Mazas and Moschato Kerkyras), while the third (Fokiano and Giouroukiko) was invalidated at two loci, sustaining the hypothesis that both cultivars could be clones of the same cultivar. On the other hand, homonymy such as Roditis kokkinos and Roditis lefkos and Romeiko and Romeiko Machaira did not overlap any genetic synonymy. In three other cases, two cultivars differed only in one out of 22 alleles with the consequence that these pairs of cultivars can be considered as clones.