RNA 5-methylcytosine (m5C) plays an undefined role in plant antiviral defense. Here, we reveal that the wheat methyltransferase NOP2/Sun RNA methyltransferase 2 (TaNSUN2) is an RNA m5C methyltransferase recruited by eukaryotic elongation factor 1-alpha (TaeEF1A) into Chinese wheat mosaic virus (CWMV) replication complexes (VRCs). TaNSUN2 promotes the m5C modification of CWMV RNAs to stabilize them and enhance their translational efficiency. Moreover, m5C 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 m5C 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.
Jiang et al. (Wed,) studied this question.