Root stem cell niche networks: it's complexed! Insights from Arabidopsis.

Renan Pardal,Renze Heidstra,Kris Vissenberg

doi:10.1093/jxb/erab272

Renan Pardal, Renze Heidstra + Show 1 more

Open Access

https://doi.org/10.1093/jxb/erab272

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Abstract

The presence of two meristematic cell populations in the root and shoot apex allows plants to grow indefinitely. Due to its simple and predictable tissue organization, the Arabidopsis root apical meristem remains an ideal model to study mechanisms such as stem cell specification, asymmetric cell division, and differentiation in plants. The root stem cell niche consists of a quiescent organizing centre surrounded by mitotically active stem cells, which originate all root tissues. The transcription factors PLETHORA, SCARECROW, and WOX5 form signalling hubs that integrate multiple inputs from an increasing number of proteins implicated in the regulation of stem cell niche function. Recently, locally produced auxin was added to the list of important mobile factors in the stem cell niche. In addition, protein–protein interaction data elegantly demonstrate how parallel pathways can meet in a common objective. Here we discuss how multiple networks converge to specify and maintain the root stem cell niche.

Highlights

Unlike animals, plants display indefinite growth and produce organs throughout their life cycle
By exploring previous and recent data, we address the interaction between well-known factors such as PLETHORA, SCARECROW, and WUSCHEL RELATED HOMEOBOX 5 (WOX5) in the establishment of a functional root organizing centre
Expressed from its own promoter, WOX5–3xYFP was unable to prevent the phenotype of starch accumulation in the columella initials when introduced in the wox5-1 mutant background. Despite this stem cell differentiation phenotype, expression of the quiescent centre (QC) identity marker QC184 was restored in the wox5-1 mutant indicating the WOX5– 3xYFP fusion protein was functional. These results indicate that WOX5 mobility is required for columella stem cell maintenance but not for QC fate (Pi et al, 2015).To elucidate the function of WOX5 in stem cell maintenance, transcriptomics, chromatin immunoprecipitation (ChIP), and protein–protein interaction experiments were performed.These revealed that WOX5 binds to the promoter region of CYCLING DOF FACTOR 4 (CDF4), where it forms a complex with TOPLESS/TOPLESS-RELATED (TPL/ TPR) and HISTONE DEACETYLASE 19 (HDA19) proteins, leading to CDF4 transcriptional repression

Summary

Introduction

Plants display indefinite growth and produce organs throughout their life cycle. These results indicate that WOX5 mobility is required for columella stem cell maintenance but not for QC fate (Pi et al, 2015).To elucidate the function of WOX5 in stem cell maintenance, transcriptomics, ChIP, and protein–protein interaction experiments were performed.These revealed that WOX5 binds to the promoter region of CYCLING DOF FACTOR 4 (CDF4), where it forms a complex with TOPLESS/TOPLESS-RELATED (TPL/ TPR) and HISTONE DEACETYLASE 19 (HDA19) proteins, leading to CDF4 transcriptional repression.

Results

Conclusion