Kenesi Erzsébet, Lopez-Moya Juan-Jose, Orosz László, Burgyán József, Lakatos Lóránt
Biological Research Center Szeged, Institute of Plant Biology, Photo- and Chronobiology Group Eötvös Loránd Research Network (ELKH), H-6726 Szeged, Hungary.
Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, 08193 Barcelona, Spain.
Plants (Basel). 2021 Apr 26;10(5):867. doi: 10.3390/plants10050867.
RNA silencing is a sequence specific post-transcriptional mechanism regulating important biological processes including antiviral defense in plants. Argonaute (AGO) proteins, the catalytic subunits of the silencing complexes, are loaded with small RNAs to execute the sequence specific RNA cleavage or translational inhibition. Plants encode several AGO proteins and a few of them, especially AGO1 and AGO2, have been shown to be required for antiviral silencing. Previously, we have shown that the P1 protein of the sweet potato mild mottle virus (SPMMV) suppresses the primary RNA silencing response by inhibiting AGO1. To analyze the role of AGO2 in antiviral defense against the SPMMV, we performed a comparative study using a wild type and ago2 mutant . Here we show that the AGO2 of attenuates the symptoms of SPMMV infection. Upon SPMMV infection the levels of AGO2 mRNA and protein are greatly increased. Moreover, we found that AGO2 proteins are loaded with SPMMV derived viral small RNAs as well as with miRNAs. Our results indicate that AGO2 protein takes over the place of AGO1 to confer antiviral silencing. Finally, we provide a plausible explanation for the AGO2 mediated recovery of an SPMMV-infected sweet potato.
RNA沉默是一种序列特异性的转录后机制，可调节包括植物抗病毒防御在内的重要生物学过程。AGO（Argonaute）蛋白作为沉默复合体的催化亚基，与小RNA结合以执行序列特异性的RNA切割或翻译抑制。植物编码多种AGO蛋白，其中一些，特别是AGO1和AGO2，已被证明是抗病毒沉默所必需的。此前，我们已经表明甘薯轻斑驳病毒（SPMMV）的P1蛋白通过抑制AGO1来抑制初级RNA沉默反应。为了分析AGO2在抗SPMMV病毒防御中的作用，我们使用野生型和ago2突变体进行了一项比较研究。在此我们表明，AGO2可减轻SPMMV感染的症状。在感染SPMMV后，AGO2的mRNA和蛋白质水平大幅增加。此外，我们发现AGO2蛋白既结合了源自SPMMV的病毒小RNA，也结合了miRNA。我们的结果表明，AGO2蛋白取代了AGO1的位置来赋予抗病毒沉默作用。最后，我们为AGO2介导的SPMMV感染甘薯的恢复提供了一个合理的解释。
