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Type: Journal article
Title: Dose-dependent AGO1-mediated inhibition of the miRNA165/166 pathway modulates stem cell maintenance in Arabidopsis shoot apical meristem
Author: Du, F.
Gong, W.
Bosca, S.
Tucker, M.R.
Vaucheret, H.
Laux, T.
Citation: Plant Communications, 2020; 1(1):100002-1-100002-11
Publisher: Elsevier
Issue Date: 2020
ISSN: 2590-3462
Statement of
Fei Du, Wen Gong, Sonia Bosca, Matthew Tucker, Herve, Vaucheret, and Thomas Laux
Abstract: Pluripotent stem cells localized in proliferating growth centers, the meristems, are the origin of life-long organ formation and growth in higher plants. In the shoot apical meristem of Arabidopsis thaliana, the closely related ARGONAUTE proteins AGO1 and ZLL/AGO10 bind miR165/166 species to regulate mRNAs of HD-ZIP III transcription factors that are essential to maintaining stem cells. Several genetic studies showed that AGO1 and ZLL/AGO10 act redundantly to maintain stem cells. By contrast, the reported biochemical data suggested antagonistic functions: AGO1 utilizes miR165/166 to slice HD-ZIP III mRNAs, whereas ZLL/AGO10 promotes degradation of miR165/166 and thus stabilizes HD-ZIP III mRNAs. How these different functions are balanced in stem cell regulation has remained enigmatic. Here, we show that autorepression of AGO1 through miR168-mediated slicing of its own RNA is required to maintain the ability of AGO1 to suppress HD-ZIP III mRNAs. Increased AGO1 expression, either in the miR168a-2 mutant or by transgenic expression, inhibits this ability despite the presence of high levels of miR165/166, effectively uncoupling HD-ZIP III and miR165/166 expression. AGO1 activity can be restored, however, by increasing the levels of chaperones SQN and HSP90, which promote assembly of RNA-induced silencing complex (RISC). This suggests that cellular abundance of SQN and HSP chaperones limits AGO1-mediated RNA interference in shoot meristem stem cell regulation. Localized misexpression of AGO1 indicates that the cells surrounding the shoot meristem primordium play a crucial role in stem cell development. Taken together, our study provides a framework that reconciles biochemical and genetic data, showing that restriction of AGO1 levels by miR168-mediated autorepression is key to RISC homeostasis and the function of AGO1 in stem cell regulation.
Keywords: Arabidopsis; ARGONAUTE1; ZWILLE (ARGONAUTE10); HD-ZIP III; stem cell; shoot meristem
Rights: © 2019 The Authors.This is an open access article under the CC BY-NC-ND license (
RMID: 1000017130
DOI: 10.1016/j.xplc.2019.100002
Grant ID:
Appears in Collections:Agriculture, Food and Wine publications

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