Ecology and Genetics of Natural Populations of North American Vitis Species Used as Rootstocks in European Grapevine Breeding Programs

Three North AmericanVitisspecies (V. riparia, V. berlandieri, V. rupestris) became widely used in rootstock breeding programs following the expansion of North American pests and diseases introduced in vineyards of the world during the 19th century. When they escape, they become feral in the most dynamic parts of Mediterranean floodplains. To better understand this ongoing process, we studied the ecology of Vitis species in their native sympatric range. We analyzed in deep 61 plots of 710 m2 containing Vitaceae species along 216 km of the Buffalo River and adjacent plateaus (Arkansas, United States). We investigated the populations structure and genetics of theVitiscomplex (i.e., possible hybrids and theVitisspecies) and the sharing of habitats with other Vitaceae (Muscadinia rotundifoliaandParthenocissus quinquefolia). Vitaceae share space according to their life strategies and microhabitat along ecological gradients. The plateau niche seems optimal forV. berlandieriandV. aestivalis.V. berlandieriis also found in alluvial zones. The most erosive parts of the river are colonized byV. rupestris, whereas the first terraces include most of theM. rotundifoliapopulations.Vitis ripariaandParthenocissuslive in the largest range of forest habitats, from plateaus to alluvial forests, and from the forest floor to the canopy, with the highest densities along the river. Interestingly, natural hybridization can occur, but establishment success is rare and limited to alluvial forests. In their native range, these populations are controlled by biotic and abiotic conditions. In Europe, the biotic relations among species are different. Our study shows thatV. ripariaand its hybrids could be the best candidates for a large scale invasion.