Enhancing plant antiviral responses and productivity through the elimination of m(5)C methyltransferase.

RNA 5-methylcytosine (m(5)C) plays an undefined role in plant antiviral defense. Here, we reveal that the wheat methyltransferase NOP2/Sun RNA methyltransferase 2 (TaNSUN2) is an RNA m(5)C methyltransferase recruited by eukaryotic elongation factor 1-alpha (TaeEF1A) into Chinese wheat mosaic virus (CWMV) replication complexes (VRCs). TaNSUN2 promotes the m(5)C modification of CWMV RNAs to stabilize them and enhance their translational efficiency. Moreover, m(5)C modification in RNA 3' untranslated region strengthens both TaeEF1A binding, promoting viral replication, and viral coat protein interaction, facilitating viral assembly. A major allele of TaNSUN2 prevents its interaction with TaeEF1A and hinders its entry into the VRCs to suppress m(5)C modification of viral RNAs. TaNSUN2 knockout enhances wheat resistance to CWMV and increases the weight and size of wheat grains. Our findings provide mechanistic insights into the function of RNA modifications in plant virus infection and a valuable genetic resource for future wheat breeding projects.