ARGONAUTE proteins (AGO) are key effectors of the RNA silencing pathways involved in the regulation of gene expression and in antiviral defense (Vaucheret,2008).Among the 10 AGO proteins present in Arabidopsis,AGO1 is essential for plant development and defense response,participating in both microRNA (miRNA)-and small interfering RNA (siRNA)-mediated gene silencing (Vaucheret,2008).Given that AGO1 depletion is lethal,only hypomorphic mutant plants are viable and display a large variety of developmental phenotypes (Vaucheret,2008).Importantly,the fine tuning of AGO1 content is an important process orchestrated by several different pathways (Cho et al.,2016).It was recently described that the mode of action of AGO1 is not only restricted to the posttranscriptional gene silencing pathway taking place in the cytoplasm.Indeed,several nuclear AGO1 functions have been identified (Bajczyk et al.,2019).Thus,the characterization of the different AGO1 pools implies that specific subcellular pathways might trigger AGO1 tuover and that complex regulatory processes might interplay to specifically fine tune AGO1 content.