A P-Loop NTPase Regulates Quiescent Center Cell Division and Distal Stem Cell Identity through the Regulation of ROS Homeostasis in Arabidopsis Root.

Qianqian Yu,Kun Yue,Bing Zhang,Huiyu Tian,Zhaojun Ding,Jiajia Liu,Xugang Li,Philip N Benfey

doi:10.1371/journal.pgen.1006175

Qianqian Yu, Kun Yue + Show 6 more

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https://doi.org/10.1371/journal.pgen.1006175

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Journal: PLoS Genetics	Publication Date: Sep 1, 2016
Citations: 83	License type: CC BY 4.0

Affiliation: Shandong University, University of Jinan

Abstract

Reactive oxygen species (ROS) are recognized as important regulators of cell division and differentiation. The Arabidopsis thaliana P-loop NTPase encoded by APP1 affects root stem cell niche identity through its control of local ROS homeostasis. The disruption of APP1 is accompanied by a reduction in ROS level, a rise in the rate of cell division in the quiescent center (QC) and the promotion of root distal stem cell (DSC) differentiation. Both the higher level of ROS induced in the app1 mutant by exposure to methyl viologen (MV), and treatment with hydrogen peroxide (H2O2) rescued the mutant phenotype, implying that both the increased rate of cell division in the QC and the enhancement in root DSC differentiation can be attributed to a low level of ROS. APP1 is expressed in the root apical meristem cell mitochondria, and its product is associated with ATP hydrolase activity. The key transcription factors, which are defining root distal stem niche, such as SCARECROW (SCR) and SHORT ROOT (SHR) are both significantly down-regulated at both the transcriptional and protein level in the app1 mutant, indicating that SHR and SCR are important downstream targets of APP1-regulated ROS signaling to control the identity of root QC and DSCs.

Highlights

Root growth is maintained by the root apical meristem, which harbors the so-called “quiescent center” (QC) and its surrounding stem cells within the stem cell niche (SCN) [1]
We characterized an Arabidopsis thaliana P-loop NTPase encoded by APP1 regulates root stem cell niche identity through its control of local Reactive oxygen species (ROS) homeostasis
The app1 mutant shows a reduction in ROS level, a rise in the rate of cell division in the quiescent center (QC) and the promotion of root distal stem cell (DSC) differentiation

Summary

Introduction

Root growth is maintained by the root apical meristem, which harbors the so-called “quiescent center” (QC) and its surrounding stem cells within the stem cell niche (SCN) [1]. In Arabidopsis, the root apical meristem (RAM) has multiple molecular signal modules that regulate SCN. The GRAS transcription factor SCARECROW (SCR) is required to establish the QC identity and root stem cell activity [5]. The transcription factor MYB DOMAIN PROTEIN 36 (MYB36), which regulates the transition from proliferation to differentiation in the endodermis, was recently identified to be directly activated by SCR [8]. SCR is regulated by another GRAS transcription factor SHORT ROOT (SHR), which is expressed in the stele and moves into the surrounding tissue layer to directly activate SCR expression by binding to the SCR promoter. Distal PLT transcript accumulation is overlapped with the radial expression domains of SCR and SHR, providing positional information for the root SCN [11]

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