CROP WILD RELATIVES

ABSTRACT: Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi, the European Wild Grape and ancestor of cultivated grapevine varieties (V. vinifera L. ssp. vinifera) is the sole wild grapevine species existing in Europe. This important crop wild relative (CWR) species is almost extinct, and persists only in residual habitats. Since these habitats are close to vineyards, this CWR species is endangered by hybridisation with its descendant crop and naturalised rootstocks that originate from viticulture. For this reason, we addressed two questions: To what extent have the remaining South German European Wild Grape accessions escaped hybridisation and preserved genetic identity? Second, what is the potential of this CWR species as a genetic resource for breeding in relation to several grapevine diseases? Using a set of highly resolving genetic markers, we were able to exclude introgression of autochthonous sylvestris accessions by cultivated grapevine. However, we detected introgression mostly from wild American species used as rootstocks in viticulture. The autochthonous accessions can be grouped into clusters. Comparative inoculation studies with the grapevine pathogens powdery mildew (Erysiphe necator), downy mildew (Plasmopara viticola), and black rot (Guignardia bidwellii) revealed relatively high levels of resistance in some of the ssp. sylvestris accessions and represents a valuable genetic resource for resistance breeding.