A single phosphorylatable amino acid residue is essential for the recognition of multiple potyviral HCPro effectors by potato Ny.

Potato virus Y (PVY, Potyviridae) is among the most important viral pathogens of potato. The potato resistance gene Ny confers hypersensitive resistance to the ordinary strain of PVY (PVY), but not the necrotic strain (PVY). Here, we unveil that residue 247 of PVY helper component proteinase (HCPro) acts as a central player controlling Ny strain-specific activation.