Ny-1 and Ny-2 genes conferring hypersensitive response to potato virus Y (PVY) in cultivated potatoes: mapping and marker-assisted selection validation for PVY resistance in potato breeding

Potato virus Y (PVY) is one of the most important viruses affecting potato (Solanum tuberosum) production. In this study, a novel hypersensitive response (HR) gene, Ny-2, conferring resistance to PVY was mapped on potato chromosome XI in cultivar Romula. In cultivars Albatros and Sekwana, the Ny-1 gene was mapped on chromosome IX. In cv. Romula, the local lesions appeared in leaves inoculated with the PVYN-Wi isolate at 20 and 28 A degrees C; PVY systemic infections were only occasionally observed at the higher temperature. In cvs. Albatros and Sekwana, expression of the necrotic reaction to virus infection was temperature-dependent. PVYN-Wi was localized at 20 A degrees C; at 28 A degrees C, the systemic, symptomless infection was observed. We developed the B11.6(1600) marker co-segregating with Ny-2 and the S1d11 marker specific for the Ny-1 gene. Fifty potato cultivars were tested with markers B11.6 and S1d11 and marker SC895 linked to the Ny-1 gene in cv. Rywal. These results indicated the utility of these markers for marker-assisted selection of HR-like PVY resistance in potato breeding programs.