Insights into the Vitis complex in the Danube floodplain (Austria)

Abstract

European grapevine populations quickly disappeared from most of their range, massively killed by the spread of North American grapevine pests and diseases. Nowadays taxonomic pollution represents a new threat. A large Vitis complex involves escaped cultivars, rootstocks, and wild grapevines. The study aimed to provide insight into the Vitis complex in the Danube region through field and genetic analyses. Among the five other major rivers in Europe which still host wild grapevine populations, the Danube floodplain is the only one benefiting from an extensive protected forest area (93 km²) and an relatively active dynamic flood pulse. The Donau‐Auen National Park also regroups the largest wild grapevine population in Europe. Ninety‐two percent of the individuals collected in the park were true wild grapevines, and 8% were hybrids and introgressed individuals of rootstocks, wild grapevines, and cultivars. These three groups are interfertile acting either as pollen donor or receiver. Hybrids were established within and outside the dykes, mostly in anthropized forest edges. The best‐developed individuals imply rootstock genes. They establish in the most erosive parts of the floodplain. 42% of the true wild grapevines lived at the edges of forest/meadow, 33.3% at the edges forest/channels, and 23.9% in forest gaps. DBH (Diameter Breast Height) varied significantly with the occurrence of flooding. Clones were found in both true wild and hybrids/introgressed grapevines. The process of cloning seemed to be prevented in places where flooding dynamics is reduced. The current global distribution of true wild grapevines shows a strong tendency toward clustering, in sites where forestry practices were the most extensive. However, the reduced flooding activity is a danger for long‐term sustainability of the natural wild grapevine population.

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

“…In contrast, in the Danube alluvial forests of Austria where abiotic conditions are close to those of the Rhone tributaries, populations of wild grapevines are well-established and rootstock crossings do not enter the forest. Instead, they are established in anthropized zones along the main stream (Arnold et al, 2017).…”

“…Twenty-three SSR primers were used; all were developed on Vitis species ( Table 1). The primers had already been tested on accessions of Vitis species and common rootstock clones from the collections of the Institut für Rebenzüchtung Geilweilerhof (Germany) and from the Agroscope Viticulture Research Center Pully (Switzerland), as well as on populations of escaped rootstocks (Arrigo and Arnold, 2007;Arnold et al, 2017; unpublished studies O. Bachmann).…”

“…Generally, escaped rootstocks establish close to vineyards, where female individuals produce fruits that attract dispersers. Adult plants are usually observed along rivers, roads, dykes, and fallows (Laguna, 2003;Arrigo and Arnold, 2007;Arnold and Schnitzler, 2008;Zecca et al, 2009;Melendez et al, 2016;Arnold et al, 2017). The survival of rootstocks can principally be explained by their tolerance to downy, powdery mildew, and phylloxera (Laguna, 2003;Melendez et al, 2016).…”

“…These feral populations are present in habitats characteristic of the Eurasian Vitis vinifera ssp sylvestris (screes or alluvial forests) but have also colonized new habitats such as hedges, streamside hedges (Arrigo and Arnold, 2007), and the most erosive parts of floodplains (Arnold et al, 2017). As a result, current wild populations of Vitis are made up of interspecific individuals with enormous genetic diversity and benefiting from exchanges with several genes of resistance to biotic or abiotic stresses (Galet, 1989;Laguna, 2003;Arrigo and Arnold, 2007).…”

“…This process has contributed to the eradication of the endemic wild grapevine V. vinifera ssp sylvestris, already endangered by American pests and pathogens and large-scale habitat destruction (Arnold et al, 1998;Arnold et al, 2010). Only a few sites are still preserved against the invasion of exotic Vitis (Arnold, 2002, Arnold et al, 2005Arnold et al, 2010;Arnold et al, 2017;Schnitzler et al, 2018).…”