What 2,900 wild grapevines reveal about the genetic diversity of Vitis vinifera L. subsp. sylvestris

Abstract

Vitis vinifera L. subsp. sylvestris is the wild ancestor of the European cultivated grapevine (V. vinifera L. subsp. sativa). The recent identification of valuable alleles associated with abiotic stress tolerance and disease resistance in this subspecies has led to coordinated efforts towards the identification, characterization and preservation of the few remaining populations still present in river valleys, forest margins, and humid habitats throughout Europe, Western Asia, and North Africa. Previous genetic studies indicated the presence of two major sylvestris ecotypes, with genomic signatures differentiating populations of western and eastern origin. These works also indicated strong genetic differences between sylvestris and sativa populations, as well as important gene flow between them due to their prolonged coexistence.

However, an in-depth characterization of this subspecies is still needed to fully resolve its population structure, useful to inform effective conservation and management strategies.

In this cooperative work, we performed the genetic characterization of 1,460 newly sampled sylvestris individuals by a set of standard SSR markers, which were merged with those already available in the literature. Following rigorous data curation and allele size standardization based on reference cultivars and allelic frequency patterns, this approach generated the largest dataset of genetic profiles for this subspecies available to date, compiling over 2,900 unique genetic profiles from 21 countries falling within its natural habitat range. Population structure analyses divided these genetic profiles into two ancestral genetic groups, broadly corresponding to the division of this subspecies into western and eastern ecotypes, and supporting the approach adopted in this study. Finer levels of resolution revealed a more complex genetic structure, identifying up to five well-defined genetic subgroups that correspond to the geographic origins of the sampled genotypes: the Southern Caucasus, the Middle East, the Maghreb and Iberian Peninsula, Central Europe and the Balkans, and a narrowly distributed group restricted to Central European regions of Austria and Slovenia. Complementary phylogenetic and dissemination modelling analyses supported this subdivision level, and facilitated inference of the relationships and potential evolutionary pathways among the identified genetic subgroups. Overall, this study provides an updated global assessment of the genetic diversity of this endangered subspecies and delivers valuable information for its effective management and conservation.

Acknowledgements

This work was supported by the European Cooperative Programme for Plant Genetic Resources (ECPGR, https://www.ecpgr.org/).