The Transcription Factor DPB Confers Antiviral Defence Against Potato Virus X by Modulating MYB-Dependent Signalling.

As a transcriptional co-factor of E2F, DP proteins are typically involved in the regulation of plant cell-cycle-related processes. However, whether DP proteins participate in transcriptional regulation associated with plant antiviral defence remains largely unclear. This study demonstrates that NbDPB, a DP family protein in Nicotiana benthamiana, positively regulates resistance to potato virus X (PVX) by functioning as a transcription factor. Knockout of NbDPB increased plant susceptibility to PVX, while its overexpression significantly suppressed viral accumulation. Furthermore, we identified that NbDPB binds to the promoter of NbMYB (a MYB transcription factor) and positively regulates its expression. Silencing NbMYB enhanced PVX infection, whereas exogenous application of jasmonic acid (JA) and salicylic acid (SA) partially rescued this phenotype. Hormone levels of JA and SA, as well as the expression levels of their marker genes, were significantly reduced in the silenced NbMYB plants. These findings suggest that the NbDPB-NbMYB module mediates antiviral defence through the JA and SA signalling pathways. This study reveals a previously uncharacterized role of DP proteins in antiviral transcriptional regulation, indicating that they may play a crucial role in plant antiviral defence.