P-248 - Inhibition of antiviral stress granule by geminivirus replication-associated protein ensures efficient virus infection

Multiple layers of defence responses are activated upon pathogen attack. Viruses employ a number of strategies to antagonize the antiviral arsenal of plants. Stress granules are non-membranous cytoplasmic granular structures that can be induced in response to diverse cellular stresses. Here, we uncover impairing stress granule formation by the replication-associated protein (Rep) of geminivirus facilitates virus infection. We find that the Rep protein of tomato yellow leaf curl virus (TYLCV) interacts with Ras-GAP SH3 domain-binding protein (G3BP1), the core nucleating component of stress granule. We show that overexpression of G3BP1 attenuates TYLCV infection, whereas knocking out of NbG3BP1 increases plant susceptibility to TYLCV. To evade stress granule-mediated antiviral response, Rep targets G3BP1 and mediates degradation of G3BP1 to impair stress granule formation. We further demonstrate that Rep recruits ATG8h and hijacks the autophagy machinery to degrade G3BP1, thus antagonizing stress granule formation. Importantly, the association of Rep with G3BP1 is required for efficient infection of several geminiviruses. Our findings suggest that geminivirus Rep promotes viral infection by inhibiting formation of antiviral stress granules, and reveal a relatively conserved mechanism on counter-defensing host antiviral responses by geminiviruses.