EXPLOITATION OF THE GENETIC DIVERSITY: AN APPROACH TO ELUCIDATE RESISTANCE

Abstract

Downy and powdery mildew, the two most threatening fungal diseases affecting grapevine cultivars are caused by Plasmopara viticola and Uncinula necator. Resistance to these pathogens is exclusively found in North-American and Asian genepools of Vitis which represent valuable genetic resources for resistance breeding. To get a better understanding of the complex mechanisms of resistance and quality parameters at the molecular level, the genetic diversity of a representative collection of Vitis accessions including various interspecific hybrids and Vitis species is being studied in a trilateral cooperation including Germany (Geilweilerhof), France (Genoplante), and Spain (MCyT). The first step is the establishment of a European grapevine CoreCollection comprising a maximum of allelic and phenotypic diversity represented within the collections of the three countries located at Montpellier (F), El Encin (E), and Siebeldingen (D). Genotyping of grapevine accessions is performed using a set of 20 microsatellites evenly distributed throughout the genome. The evaluation of the phenotypic data is based on internationally accepted OIV descriptors for Plasmopara viticola and Uncinula necator resistance. In the near future, the European Vitis CoreCollection will allow us to identify allelic variants of candidate genes for these traits and to elucidate the extent of nucleotide diversity. This project will construct a well-defined characterized Vitis CoreCollection and generate a valuable instrument for the extended use of the naturally existing variability in the Vitis gene pool.