An E3 ligase-competent transcription factor orchestrates dual antiviral defenses against strawberry vein banding virus

During the "arms race" between viruses and plants, plants have evolved various antiviral immune defense responses, among which the most direct and effective is disrupting the accumulation of viral nucleic acids and proteins, thereby inhibiting viral infection. However, few studies have reported on the antiviral proteins of strawberry (Fragaria vesca) plants. Here, we report that zinc finger protein 1 (FvZFP1) from F. vesca interacts with the strawberry vein banding virus (SVBV) P6 protein. SVBV infection upregulated FvZFP1 expression, while FvZFP1 protein overexpression induced P6 degradation via the 26S proteasome and inhibited virus infection. FvZFP1 showed E3 ubiquitin ligase activity and promoted P6 ubiquitination both in vitro and in vivo. The interaction between P6 and FvZFP1, mediated by the key amino acids P6 Gln-174 and FvZFP1 Glu-146, was crucial for FvZFP1 to promote the ubiquitination and degradation of P6. Moreover, FvZFP1 acted as a transcription factor that bound to the SVBV 35S promoter, inhibiting its transcriptional activity and reducing viral replication levels. Overall, our results demonstrate a strawberry plant antiviral mechanism whereby ZFP1 defends against SVBV infection by targeting P6 abundance and viral nucleic acid levels.