Glycolate oxidase contributes to autophagy-associated antiviral defense against citrus leaf blotch virus

Abstract Background Kiwifruit is a high-value fruit crop but is increasingly challenged by viral diseases. Citrus leaf blotch virus (CLBV), an important viral pathogen of kiwifruit, causes vein clearing and chlorotic symptoms in leaves, severely impairing kiwifruit yield and fruit quality. Reactive oxygen species (ROS) are recognized as pivotal signals in plant antiviral defense, yet the downstream pathway by which virus-induced H₂O₂ accumulation restricts viral infection remains largely unclear. Results Glycolate oxidase (GOX) expression is positively associated with H₂O₂ accumulation and autophagic activity, but negatively associated with CLBV accumulation. CLBV infection in Nicotiana benthamiana was associated with elevated H₂O₂ accumulation and marked upregulation of GOX, a key peroxisomal enzyme responsible for H₂O₂ production. GOX-mediated H₂O₂ accumulation functions as an antiviral barrier against CLBV, as NbGOX silencing enhanced viral infection and kiwi ( Actinidia chinensis ) AcGOX5 overexpression reduced viral accumulation. Further analyses revealed that among the domains in CLBV replicase, the expression of PRO and OTu domains promote H₂O₂ accumulation. Mechanistically, GOX contributes to CLBV restriction and is associated with enhanced autophagic activity and reduced accumulation of the viral movement protein. Conclusions Together, these findings reveal a mechanistic link between oxidative signaling and autophagy in plant antiviral immunity and highlight GOX-mediated H₂O₂ accumulation as an important component of host defense against virus.