Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 5.57

DEVELOPMENT AND TRANSFERABILITY OF GRAPE EST-SSR MARKERS SUITABLE FOR MAPPING IN VITIS SPP.

F. SEVINI, R. MARINO, C. SEGALA, M.S. GRANDO

Lab. of Molecular Genetics, Istituto Agrario San Michele all’Adige, via Mach 1, 38010 San Michele a/A, Trento, Italy

Vitis, EST, SSR, allelic variants

Screening of a grapevine EST library of 960 sequences revealed 78 sequences containing mono, di and trinucleotide SSR motifs. Such microsatellites, belonging to expressed regions, should be more informative in mapping loci with a specific genetic function.

Twenty-five of them were selected to design a set of primer combinations and tested on five grape genotypes composed by wild and cultivated Vitis vinifera and American Vitis species. In addition, 24 SSR markers, developed by our group in the frame of the Vitis Microsatellite Consortium (VMC), were also tested for amplification, polymorphism and transferability across the same set of genotypes.

Six EST and 9 VMC derived primer pairs generated polymorphic markers which were used to evaluate the diversity of a larger set of grape accessions. As reported in previous studies, we found that the flanking regions were conserved among different species and the amplification products were in the same size range for all the tested individuals. Allelic variants ranging from a minimum of 3 different alleles (EST2a10 locus) and a maximum of 16 different alleles (VMC 4d9.2 locus) were observed at several loci for different accessions. The allelic frequencies in the Vitis vinifera set resulted very different between cultivated varieties (Vitis vinifera sativa) and wild accessions of Vitis vinifera silvestris, but it was not possible to identify alleles useful to distinguish the two groups of individuals. We could not distinguish between mutants since no one of the developed markers resulted polymorphic within the same variety (i.e. Chardonnay, Pinot). Nevertheless, in some cases we observed more than two alleles at the same locus that could indicate the presence of chimerism.

In comparison to EST derived markers, the SSRs of VMC library resulted much more polimorphic. However, although the low number of tandem repeats we found that these grape ESTs have a suitable variability to allow the mapping of related functional genes.