Genetic diversity and phylogeographic structure of the genus Vitis: implications for conservation.

Authors: Aradhya, Mallikarjuna; Prins, Bernard - Bernie; DANGLS, GERALD - UCD - FPS; Simon, Charles; Stover, Eddie

Submitted to: International Conference on Crop Wild Relative Conservation and Use
Publication Type: Proceedings
Publication Acceptance Date: 10/5/2005
Publication Date: N/A
Citation: N/A

Interpretive Summary: Three hundred sixty grape accessions representing 44 taxa from both the Old and New World distributions were genotyped using 10 microsatellite loci. Examination of genetic relationships within and between taxa revealed many genetic affinities roughly corresponding to the taxonomic series established based on morphological criterion. The observed and expected heterozygosity levels showed marginal deficiency of heterozygotes in most taxa suggesting some sort of population substructure within taxa. Nevertheless, there was significant differentiation between taxa as compared to between the series within Vitis. Partitioning of allelic variation within and between taxa revealed higher differentiation among taxa (~33% of total variation) than among the taxonomic series (~15% of total variation) in the genus with ~4% of the variation common to all the taxa examined. Genetic differentiation among the Chinese taxa probably reflects the hotspots of diversity in north China - Qinling-Taihang Mountains in Shanxi and Hebei provinces; central China – Shenglongjia-Dalou-Wuling Mountains in Sichuan, Hubei, and Hunan provinces; south and east China – Lingnan-Wuyi Mountains in Guandong, Fujian, Jiangxi, and Zhejiang prvinces as suggested by some Chinese taxonomists. Overall, the genetic differentiation analysis suggests the existence of complex population subdivisions within and between taxa and taxonomic series of the genus Vitis.

Technical Abstract: The genus Vitis is typically divided into two subgenera, Vitis (2n=6x=38) comprising almost all of the total of about 70 taxa described in the genus except for the two taxa, V. rotundifolia and V. popenoei, which represents the subgenus Muscadinia (2n=6x=40). About two-thirds of Vitis are native to North America and one-third distributed across Central and West Asia. Much of the taxonomic knowledge of Vitis comes from studies based on morphological criterion and riddled with difficulties in establishing identities of different taxa. This confusion is due to widespread introgression among sympatric taxa resulting in clinal variation masking the taxonomic and ecological boundaries. Three hundred sixty grape accessions representing 44 taxa with both the Old and New World distributions including the cultivated V. vinifera and its putative progenitor, V. v. ssp. sylvestris, and three taxa of Muscadinia were analyzed for genetic diversity and phylogeographic structure using 10 polymorphic microsatellite loci. We address the transportability and utility of these markers across cultivated species and their wild relatives in the characterization of gene pools for efficient conservation, management, and utilization of genetic resources. Examination of genetic diversity and structure within the genus Vitis revealed many genetic affinities more or less corresponding to the taxonomic series established based on morphological criterion. Chinese species exhibited significant genetic differentiation with as many as three major affinities along with some of them showing strong relationships with many American taxa/series. The marginal heterozygote deficiency observed for some of the loci suggests population substructuring within and between taxa. However, there was significant differentiation between taxa as compared to between series. Overall, the interplay of local differentiation and introgression has played a significant role in shaping the genetic structure in Vitis. We further discuss the implications of the complex multidimensional nature of microsatellite variability in the genus for the development of conservation and management strategies.