TuMV infection alters miR168/AGO1 and miR403/AGO2 systems regulation in Arabidopsis

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. ### Competing Interest Statement The authors have declared no competing interest.