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

Abstract

Potato virus Y (PVY) is one of the most important viruses affecting potato (<i>Solanum tuberosum</i>) production. In this study, a novel hypersensitive response (HR) gene, <i>Ny</i>-<i>2</i>, conferring resistance to PVY was mapped on potato chromosome XI in cultivar Romula. In cultivars Albatros and Sekwana, the <i>Ny</i>-<i>1</i> gene was mapped on chromosome IX. In cv. Romula, the local lesions appeared in leaves inoculated with the PVY^N-Wi isolate at 20 and 28 °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. PVY^N-Wi was localized at 20 °C; at 28 °C, the systemic, symptomless infection was observed. We developed the B11.6₁₆₀₀ marker co-segregating with <i>Ny</i>-<i>2</i> and the S1d11 marker specific for the <i>Ny</i>-<i>1</i> gene. Fifty potato cultivars were tested with markers B11.6 and S1d11 and marker SC895 linked to the <i>Ny</i>-<i>1</i> 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.