中文摘要：植物RNA依赖的RNA聚合酶(RDR1)是抗病毒RNA沉默途径的关键组成部分，其有助于病毒来源的小干扰RNA的生物合成。这种酶可生产具有病毒活性的内源性小干扰RNA，并通过抑制宿主基因的沉默来激发广谱抗病毒活性。各种植物中RDR1同源基因的表达通常是由病毒侵染引起的。然而，对于激活RDR1的表达来应对病毒侵染的分子机制仍然未知。本研究结果揭示了水稻抗病毒途径的分子级联，miR444及其MADS box靶标可通过该途径直接控制OsRDR1的转录。
外文摘要：Plant RNA-DEPENDENT RNA POLYMERASE1 (RDR1) is a key component of the antiviral RNA-silencing pathway, contributing to the biogenesis of virus-derived small interfering RNAs. This enzyme also is responsible for producing virusactivated endogenous small interfering RNAs to stimulate the broad-spectrum antiviral activity through silencing host genes. The expression of RDR1 orthologs in various plants is usually induced by virus infection. However, the molecular mechanisms of activation of RDR1 expression in response to virus infection remain unknown. Here, we show that a monocot-specific microRNA, miR444, is a key factor in relaying the antiviral signaling from virus infection to OsRDR1 expression. The expression of miR444 is enhanced by infection with Rice stripe virus (RSV), and overexpression of miR444 improves rice (Oryza sativa) resistance against RSV infection accompanied by the up-regulation of OsRDR1 expression. We further show that three miR444 targets, the MIKCC-type MADS box proteins OsMADS23, OsMADS27a, and OsMADS57, form homodimers and heterodimers between them to repress the expression of OsRDR1 by directly binding to the CArG motifs of its promoter. Consequently, an increased level of miR444 diminishes the repressive roles of OsMADS23, OsMADS27a, and OsMADS57 on OsRDR1 transcription, thus activating the OsRDR1-dependent antiviral RNA-silencing pathway. We also show that overexpression of miR444-resistant OsMADS57 reduced OsRDR1 expression and rice resistance against RSV infection, and knockout of OsRDR1 reduced rice resistance against RSV infection. In conclusion, our results reveal a molecular cascade in the rice antiviral pathway in which miR444 and its MADS box targets directly control OsRDR1 transcription.
作者：Wang, Huacai; Jiao, Xiaoming; Kong, Xiaoyu; 等
作者单位：中国科学院
期刊名称：PLANT PHYSIOLOGY
期刊影响因子：6.28
出版年份：2016
出版刊次：4
点击下载：水稻抗病毒RNA沉默途径的信号级联从miR444放大至RDR1