NtRBP45, a nuclear RNA‐binding protein of Nicotiana tabacum, facilitates post‐transcriptional gene silencing

The tobacco RBP45 is a nuclear RNA binding protein (RBP). In this study, we identified that the gene expression of NtRBP45 was significantly up‐regulated upon the Tobacco mosaic virus infection and the central region of the protein accounted for its nuclear localization. In particular, using a green fluorescent protein‐based transient suppression assay, we uncovered that the transiently overexpressed NtRBP45 was able to enhance local post‐transcriptional gene silencing (PTGS), facilitate siRNA accumulation, and compromise the RNA silencing suppression mediated by Tomato aspermy virus 2b protein. Deletion mutagenesis showed that both the N‐ and C‐terminal regions of NtRBP45 were necessary for enhancing PTGS. The data overall indicated a novel RNA silencing factor that might participate in antiviral defense.