Abstract
Three potato cultivars, Payette Russet, Dark Red Norland, and Chieftain were challenged with four strains of potato virus Y (PVY), PVYO, PVYEu-N, PVYN-Wi, and PVYNTN. Cultivars Dark Red Norland and Chieftain exhibited strain-specific, hypersensitive resistance to PVYO and PVYNTN strains.. These same two cultivars, Dark Red Norland and Chieftain, appeared to have an additional resistance source in their genomes providing partial resistance against PVYN-Wi but were found fully susceptible to the non-recombinant PVYEu-N strain. Payette Russet was found immune to the same four strains of PVY; PVYO, PVYEu-N, PVYN-Wi, and PVYNTN, and was additionally challenged with the total of 18 isolates of PVY representing 12 genetic variants of the virus from potato and non-potato solanaceous hosts. None of the 18 isolates of the virus was found able to replicate in the inoculated or upper non-inoculated leaves of Payette Russet, confirming the broad specificity of the Rysto gene present in the Payette Russet genome.