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Plant Cell. 2017 May;29(5):1073-1087. doi: 10.1105/tpc.16.00863. Epub 2017 Apr 7.

A Two-Step Model for de Novo Activation of WUSCHEL during Plant Shoot Regeneration.

Author information

1
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Shanghai 200032, P.R. China.
2
University of Chinese Academy of Sciences, Shanghai 200032, P.R. China.
3
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, P.R. China.
4
National Center for Plant Gene Research, Beijing 100101, P.R. China.
5
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Shanghai 200032, P.R. China jwwang@sibs.ac.cn.
6
ShanghaiTech University, Shanghai 200031, P.R. China.

Abstract

Plant cells are totipotent and competent to regenerate from differentiated organs. It has been known for six decades that cytokinin-rich medium induces shoot regeneration from callus cells. However, the underlying molecular mechanism remains elusive. The homeodomain transcription factor WUSCHEL (WUS) is essential for de novo establishment of the shoot stem cell niche in Arabidopsis thaliana We found that WUS-positive (WUS+) cells mark the shoot progenitor region during regeneration. A cytokinin-rich environment initially promotes the removal of the repressive histone mark H3K27me3 at the WUS locus in a cell cycle-dependent manner. Subsequently, the B-type ARABIDOPSIS RESPONSE REGULATORs (ARRs) ARR1, ARR2, ARR10, and ARR12, which function as transcriptional activators in the cytokinin signaling pathway, spatially activate WUS expression through binding with microRNA165/6-targeted HD-ZIP III transcription factors. Thus, our results provide important insights into the molecular framework for cytokinin-directed shoot regeneration and reveal a two-step mechanism for de novo activation of WUS.

PMID:
28389585
PMCID:
PMC5466026
DOI:
10.1105/tpc.16.00863
[Indexed for MEDLINE]
Free PMC Article

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