Small RNA-mediated RNA silencing is an important antiviral mechanism in higher plants. It has been shown that RNA silencing components can be upregulated by viral infection. However, the mechanisms underlying the upregulation remain largely unknown. Here, we show that jasmonate (JA) signaling transcriptionally activates Argonaute 18 (AGO18), a core RNA silencing component that promotes rice antiviral defense through sequestering miR168 and miR528, which repress key antiviral defense proteins. Mechanistically, the JA-responsive transcription factor JAMYB directly binds to the AGO18 promoter to activate AGO18 transcription. Rice stripe virus (RSV) coat protein (CP) triggers JA accumulation and upregulates JAMYB to initiate this host defense network. Our study reveals that regulatory crosstalk exists between the JA signaling and antiviral RNA silencing pathways and elucidates a molecular mechanism for CP-mediated viral resistance in monocot crops.

小RNA介导的RNA沉默是高等植物中重要的抗病毒机制。已经显示RNA沉默组分可以通过病毒感染而被上调。但是，上调的潜在机制仍然未知。在这里，我们显示茉莉酸（JA）信号转录激活Argonaute 18（AGO18），这是一种核心RNA沉默成分，可通过螯合miR168和miR528来抑制水稻的抗病毒防御蛋白，从而提高水稻的抗病毒防御能力。从机理上讲，JA响应转录因子JAMYB直接与AGO18启动子结合以激活AGO18转录。水稻条纹病毒（RSV）外壳蛋白（CP）触发JA积累并上调JAMYB以启动该宿主防御网络。我们的研究表明，JA信号传导和抗病毒RNA沉默途径之间存在调控串扰，并阐明了单子叶植物中CP介导的病毒抗性的分子机制。