Drought-Induced ABA Suppresses Geminivirus Replication by Downregulating PCNA Expression via the Transcription Factor...

Geminiviruses, mainly transmitted by whitefly Bemisia tabaci, pose significant constrains to agricultural productivity. Under climate change, drought conditions may contribute to the spread of geminiviruses through creating favourable conditions for whitefly proliferation. Additionally, lots of geminiviruses could enhance plant drought tolerance, supporting their survival and propagation. However, the effects of drought stress on plant resistance to geminiviruses remain unclear. In this study, we demonstrate that drought stress significantly reduces the accumulation of DNA viruses, including tomato yellow leaf curl virus and Sri Lankan cassava mosaic virus, while the accumulation of the +ssRNA virus turnip mosaic virus remains unaffected. We show that drought does not affect RNA silencing pathway. Interestingly, drought-induced abscisic acid (ABA) inhibits geminiviruses replication by reprogramming the cell cycle and suppressing the expression of proliferating cell nuclear antigen (PCNA), a component of DNA replication complex. Moreover, we identify that the ABA-responsive transcription factor NAC072 directly binds to the PCNA promoter, negatively regulating its expression. These findings provide mechanistic insights into the ABA-mediated resistance against DNA viruses during drought stress and highlight the critical role of ABA in integrating plant responses to abiotic and biotic stresses.