More importantly, silencing of NbSAMS2 reversed TGS and PTGS and reduced plant resistance against two geminiviruses CLCuMuV and TYLCCNV (Figs 3 and 4 and S5 Fig), providing direct evidence that a geminivirus-encoded protein is able to promote virus infection by interfering with SAMS-mediated methylation-dependent TGS and PTGS. This evidence concerns the gene MAT1A and viral infectious disease.