Fine-tuning of the CRWN2-NTL9 module to repress PR1 expression by a viral effector during geminivirus infection

CROWDED NUCLEIs (CRWNs) are nuclear lamina proteins that play an important role in plant immunity. Nevertheless, the molecular mechanism of how CRWNs regulate host immunity and the mechanism by which pathogens manipulate CRWN-mediated immunity regulation is not understood. In this study, we report that CRWN2 negatively regulates anti-geminiviral defense responses through enhancing the function of NAC with transmembrane motif 1-like 9 (NTL9), and the CRWN2-NTL9 module attenuating host defenses is exploited by the geminivirus tomato yellow leaf curl China virus (TYLCCNV). CRWN2 directly interacts with the transcription factor NTL9 and enhances its binding activity on the promoter of the pathogenesis-related gene PR1, to negatively regulate the PR1 expression, thereby modulating host susceptibility to TYLCCNV. Interestingly, the V2 protein encoded by TYLCCNV enhances the interaction between CRWN2 and NTL9 and subsequently increases the complex's affinity for the PR1 promoter, thus suppressing PR1 expression and creating an environment suitable for virus infection. Moreover, the interaction between CRWN2 and V2 is conserved between different geminivirus species, indicating that host immunity regulation mediated by the CRWN2-NTL9 complex is co-opted by different geminiviruses.