Verification of resistance loci pyramiding in popular interspecific grape varieties using SSR markers

Fungal pathogens Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni (downy mildew) and Erysiphe necator Schwein. (powdery mildew) represent the biggest threats for grape growers worldwide. Under suitable conditions, these pathogens can spread very quickly through vineyards and cause significant damage. The most ecological way to reduce the possibility of infection in vineyards is growing interspecific genotypes which are able to suppress these pathogens and stop the spread of infection. With this in mind, 9 international and 11 Czech grapevine genotypes were analysed in order to genotype the resistance loci present in them. As a tool a set of SSR markers linked to known loci of resistance to downy and powdery mildew was used. Namely, presence of four loci responsible for resistance to Plasmopara viticola (Rpv3, Rpv4, Rpv7, and Rpv10) and two for Erysiphe necator (Ren3 and Ren9) were analysed with respective SSR markers. By this way the degree of resistance gene pyramiding was newly assessed in all analysed cultivars and their perspectives in grapevine breeding are discussed.