Population Structure of Vitis rupestris, an Important Resource for Viticulture

The wild North American grapevine Vitis rupestris Scheele is an important genetic resource for viticulture, but its natural populations have been severely depleted. We collected samples from seven V. rupestris populations from the Ozark Plateau in Missouri and the Ouachita Mountains in Oklahoma and genotyped them with 14 microsatellite markers to assess allelic diversity, heterozygosity, and genetic differentiation at various levels of population structure. We found that genetic diversity in V. rupestris was similar to that measured in many V. vinifera L. ssp. sylvestris populations and in other outcrossing angiosperms. We detected significant genetic differentiation among populations (Phi(PT) = 0.105); there was no significant deviation from Hardy-Weinberg equilibrium in some populations, and there was moderate inbreeding in others. Pronounced differentiation between Missouri and Oklahoma populations was supported by a Bayesian clustering approach and principle coordinate analyses and was apparently a function of geographic distance. Genetic differentiation among Missouri populations was modest. We posit that population differentiation and genetic drift may be inherent characteristics of V. rupestris.