Studies on varietal response to different strains of Potato virus Y (PVY) reveal hypersensitive resistance in Exploits to PVYO and extreme resistance in F87084 to all tested strains

Abstract

Potato cultivar Exploits and breeding clone F87084 have been considered resistant to Potato virus Y (PVY). To further explore the degree of resistance and whether the resistance is strain specific, these materials, together with cultivar Rochdale Gold-Doree and breeding line F02010, were investigated for their response to different PVY strains including PVYO, PVYN:O, PVYNTN and PVYN. Both F02010 and Rochdale Gold-Doree were readily infected with all tested PVY strains after either mechanical or graft inoculation, indicating susceptibility of the materials to PVY. F87084 was unable to be infected by any of the tested PVY strains as no ELISA-detectable level of PVY were found in plants after either mechanical or graft inoculation, demonstrating extreme resistance in F87084 to all strains of PVY tested. Exploits was infected with PVYN:O/PVYNTN/PVYN after either mechanical or graft inoculation, indicating susceptibility of the cultivar to these PVY strains. The cultivar was also infected readily with PVYO after graft inoculation. However, despite induction of local lesions on the inoculated leaves, mechanical inoculation with PVYO may or may not lead to systemic symptoms and ELISA-detectable level of PVY, depending on temperature. At low temperature (e.g., 22 °C), no visible systemic symptoms or ELISA-detectable level of PVY was found in the plants; whereas at high temperature (e.g., 30 °C), systemic symptoms and high level of PVY were detected in the plants. These results demonstrate that Exploits possesses temperature-dependent hypersensitive resistance to PVYO. Analysis of a segregating population of F87084 × F02010 revealed that the ER in F87084 is controlled by a dominant resistance gene.