Potyviral genome-linked protein targets NbMYB330 to attenuate hydrogen-peroxide-induced antiviral immunity in plants.

MYB transcription factors play crucial roles in orchestrating plant immunity against various pathogens. However, their regulation during virus infection and how viruses counteract these defenses remain poorly understood. In this study, we demonstrated that turnip mosaic virus (TuMV) viral genome-linked protein (VPg) interacts with Nicotiana benthamiana MYB330 (NbMYB330), an R2R3-MYB transcription factor, in the nucleus. NbMYB330 expression was activated at the early stage of TuMV infection, and NbMYB330 positively regulated host antiviral defense. NbMYB330 directly bound to the promoter region of N. benthamiana Catalase1 (NbCAT1), a key gene involved in hydrogen peroxide (H2O2) scavenging, and suppressed its expression to enhance H2O2 accumulation. TuMV VPg targeted NbMYB330 and interfered with its transcriptional repression activity, thus promoting NbCAT1 expression and H2O2 scavenging to enhance virus accumulation. Furthermore, we revealed that potato virus Y (PVY; genus Potyvirus) VPg also targets NbMYB330 to attenuate the H2O2-induced antiviral response. Collectively, our study reveals a previously uncharacterized regulatory module in the plant-potyvirus arms race.