In plants, Argonaute (AGO) proteins, essentially AGO1 and 2, restrict viral infections. These AGO proteins also participate in developmental processes and are endogenously tightly regulated by microRNAs. Under viral infections, the regulatory loop comprising miR168/AGO1 is well studied, but much less the miR403/AGO2 system. Here, we simultaneously studied the miR168/AGO1 and miR403/AGO2 regulatory systems under TuMV infection in Arabidopsis. TuMV induced downregulation of miRNAs precursor molecules, concomitantly with enhanced mature miRNAs accumulation, without evidence of transcriptional alteration. Under infection, AGO1 protein remained at basal levels whereas AGO2 overaccumulated. These results share both similarities and differences with previous reports studying abiotic and biotic impact on microRNA biogenesis and AGO-dependent antiviral defense, and expand our knowledge of the miR403/AGO2 regulatory system.

中文翻译：

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TuMV 感染改变拟南芥中 miR168/AGO1 和 miR403/AGO2 系统调控

在植物中，Argonaute (AGO) 蛋白，主要是 AGO1 和 2，限制病毒感染。这些 AGO 蛋白也参与发育过程，并受到 microRNA 的内源性严格调控。在病毒感染下，对包含 miR168/AGO1 的调节环进行了充分研究，但对 miR403/AGO2 系统的研究却少之又少。在这里，我们同时研究了拟南芥中 TuMV 感染下的 miR168/AGO1 和 miR403/AGO2 调控系统。TuMV 诱导 miRNA 前体分子的下调，伴随着成熟 miRNA 积累的增强，没有转录改变的证据。在感染下，AGO1 蛋白保持在基础水平，而 AGO2 过度积累。