|Aradhya, Mallikarjuna - UNIV CALIFORNIA, DAVIS|
|Dangl, Gerald - UNIV CALIFORNIA, DAVIS|
|Boursiquot, Jean-Michel - ENSA.M-INRA, FRANCE|
|Walker, Andrew - UNIV CALIFORNIA, DAVIS|
|Meredith, Carol - UNIV CALIFORNIA, DAVIS|
Submitted to: Genetical Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2002
Publication Date: June 1, 2003
Citation: Aradhya M.K., G. S. Dangls, B.H. Prins, J. M. Boursiquot, M.A. Walker, C.P. Meredith, C.J. Simon 2003. Genetic Structure and differentiation in cultivated grape, vitis vinifera L., Genetical Research 81: 179-192. Interpretive Summary: Eight microsatellite loci were used to assess genetic variability in a grape germplasm collection comprising 222 V. vinifera and 22 V. vinifera ssp. sylvestris accessions. The gene pool showed a significant amount of variation and differentiated into sixteen groups. The French wine grapes were distinct from the rest of the collection, and showed close affinity to ssp. sylvestris. The table and wine grapes differed significantly and the Muscat types were reasonably distinct within the wine grapes. The overall organization of genetic diversity suggests that the germplasm of cultivated grapes represents a complex gene pool and its genetic structure has been influenced by man's strong artificial selection. In regard to germplasm management, our results show that (1) the germplasm collection is highly variable and most variation (~85%) is common to all the genetic groups identified, (2) marginal gains in the variability are possible through extensive collection from diverse eco-geographic sources, (3) unique cultivated grape genotypes, wild (ssp. sylvestris) and spontaneous hybrids are the major sources of new alleles, apart from the slow process of mutation, and (4) wild grape germplasm is still a potential source of unique alleles for the improvement of both wine and table grapes.
Technical Abstract: Two hundred twenty-two Vitis vinifera and 22 wild V. vinifera ssp. sylvestris accessions were analyzed for genetic diversity and differentiation using eight microsatellite loci. A total of 94 alleles were detected with extensive polymorphism among the accessions. Cluster analysis revealed 16 genetic groups organized into three clusters, supporting the classical eco-geographic groupings, occidentalis, pontica, and orientalis. French wine cultivars were distinct and showed close affinity to ssp. sylvestris. There was appreciable differentiation between table and wine grapes and the Muscat types were distinct within the wine types. Contingency chi square analysis indicated significant heterogeneity among groups. The observed heterozygosity for different groups ranged from 0.625 to 0.9 with an average of 0.771. Genetic relationships among groups suggested hierarchical differentiation within cultivated grape. The gene diversity analysis indicated marginal divergence among groups with most variation found within groups (~85%). Partitioning of variation suggested that the remaining variation is somewhat structured at different levels of differentiation. The overall organization of genetic diversity suggests that the cultivated grape germplasm represents one complex gene pool and its structure determined by artificial selection by man.