Screening Three Potato Cultivars for Resistance to Potato Virus Y Strains: Broad and Strain-Specific Sources of Resistance

Three potato cultivars, Payette Russet, Dark Red Norland, and Chieftain were challenged with four strains of potato virus Y (PVY), PVY^O, PVY^Eu−N, PVY^N−Wi, and PVY^NTN. Cultivars Dark Red Norland and Chieftain exhibited strain-specific, hypersensitive resistance to PVY^O and PVY^NTN strains.. These same two cultivars, Dark Red Norland and Chieftain, appeared to have an additional resistance source in their genomes providing partial resistance against PVY^N−Wi but were found fully susceptible to the non-recombinant PVY^Eu−N strain. Payette Russet was found immune to the same four strains of PVY; PVY^O, PVY^Eu−N, PVY^N−Wi, and PVY^NTN, 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 Ry_sto gene present in the Payette Russet genome.