The C4 Protein of TbLCYnV Promotes SnRK1 β2 Degradation Via the Autophagy Pathway to Enhance Viral Infection in <i>N. benthamiana</i>
Xinquan Li,
Min Zhao,
Wanyi Yang,
Xueping Zhou,
Yan Xie
Affiliations
Xinquan Li
State Key Laboratory of Rice Biology and Breeding, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
Min Zhao
State Key Laboratory of Rice Biology and Breeding, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
Wanyi Yang
State Key Laboratory of Rice Biology and Breeding, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
Xueping Zhou
State Key Laboratory of Rice Biology and Breeding, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
Yan Xie
State Key Laboratory of Rice Biology and Breeding, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
Geminiviruses are a group of single-stranded DNA viruses that have developed multiple strategies to overcome host defenses and establish viral infections. Sucrose nonfermenting-1-related kinase 1 (SnRK1) is a key regulator of energy balance in plants and plays an important role in plant development and immune defenses. As a heterotrimeric complex, SnRK1 is composed of a catalytic subunit α (SnRK1 α) and two regulatory subunits, β and γ. Previous studies on SnRK1 in plant defenses against microbial pathogens have mainly focused on SnRK1 α. In this study, we validated the interaction between the C4 protein encoded by tobacco leaf curl Yunnan virus (TbLCYnV) and the regulatory subunit β of Nicotiana benthamiana SnRK1, i.e., NbSnRK1 β2, and identified that the Asp22 of C4 is critical for TbLCYnV C4–NbSnRK1 β2 interactions. NbSnRK1 β2 silencing in N. benthamiana enhances susceptibility to TbLCYnV infection. Plants infected with viral mutant TbLCYnV (C4D22A), which contains the mutant version C4 (D22A) that is incapable of interacting with NbSnRK1 β2, display milder symptoms and lower viral accumulation. Furthermore, we discovered that C4 promotes NbSnRK1 β2 degradation via the autophagy pathway. We herein propose a model by which the geminivirus C4 protein causes NbSnRK1 β2 degradation via the TbLCYnV C4–NbSnRK1 β2 interaction to antagonize host antiviral defenses and facilitates viral infection and symptom development in N. benthamiana.
