Genetic Isolation and Diffusion of Wild Grapevine Italian and Spanish Populations as Estimated by Nuclear and Chloroplast SSR Analysis

Abstract

Genetic structure of six Italian and five Spanish populations of wild grapevine (Vitis vinifera ssp. silvestris) was investigated using nuclear and chloroplast SSR analysis. Results show that the Italian populations are characterised by high genomic diversity within populations, with a peak of heterozygosity (Ho = 0.7637) for a population collected in southern Italy. However, the low haplotype richness and the high level of genetic distance detected among the Spanish populations, combined with their low gene flow, shows that these populations suffered from a genetic erosion. Genetic relationship between Italian and Spanish populations was investigated and results showed genetic differentiation between the two populations. Using nuclear and chloroplast SSR markers, the ratio between pollen and seed diffusion was estimated. High pollen flow, as compared with seed flow, suggests that seed diffusion is made difficult, probably due to low germinability and survival of seedlings in the wild. Seed germination and young plant survival must be considered a priority target for in situ conservation programmes. By providing information on population history, genetic structure and gene flow, and by identifying areas harbouring high levels of wild grape variability, this study provides the basis for the preservation of biodiversity of the wild grapevine.

Linkage disequilibrium in wild French grapevine, Vitis vinifera L. subsp. silvestris

“…It can potentially be linked to population history, particularly recent bottlenecks. At the end of the nineteenth century, wild grapevine underwent a drastic reduction in diversity, owing to the disease-causing agents mildew and phylloxera , as shown by the relative genetic diversity deficit observed in wild grapevine compared to cultivated grapevine (Aradhya et al, 2003;Grassi et al, 2003). Our results also reveal such a deficit.…”

Phylogeographical structure and conservation genetics of wild grapevine

“…This indicates a strong population differentiation and reflects low gene mixing and thus reduced gene flow among populations. The level of subdivision for microsatellite cpDNA polymorphism verified for the analysed grapevine populations is significantly higher than that recorded for nuclear polymorphisms (Grassi et al 2003a). This evidences the low efficiency of seed dissemination.…”

“…Here, G STb and G STc represent the value of population subdivision and are based on nuclear (Grassi et al 2003a) and cpDNA (this paper) markers, respectively.…”

“…In a previous paper, we verified the genetic structure of 12 wild grapevine populations collected in Italy and Spain and gained knowledge of their genetic isolation and inbreeding (Grassi et al 2003a). In the present work, the analysis was extended to 78 populations collected in their main Mediterranean distribution areas, including the Caucasus area, and DNA analysis was performed by using cpDNA microsatellite markers.…”

“…In the 1980s this subspecies was added to the IUCN List of endangered European plants. Since 2000, it has been declared a critically endangered subspecies and is strictly protected in France (Lacombe et al 2002), in the Czech Republic (Holub and Procha´zka 2000), in Spain (Ocete et al 1999) and in Italy (Grassi et al 2003a).…”