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Identification of a novel regulator involved in the Quiescent Center-independent root meristem activity in the SHORTROOT pathway

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Authors

김은솔

Advisor
이지영
Major
자연과학대학 생명과학부
Issue Date
2015-08
Publisher
서울대학교 대학원
Keywords
Quiescent centerRoot apical meristemSHORTROOT (SHR)HAWAIIAN SKIRT (HWS)
Description
학위논문 (석사)-- 서울대학교 대학원 : 생명과학부, 2015. 8. 이지영.
Abstract
Quiescent center (QC) is known to maintain the root apical meristem (RAM). In the SHORTROOT knock-out mutant (shr), root growth and QC maintenance are defective. In double knock-out mutants of SHR and PHABULOSA (PHB), root growth is recovered even though QC remains absent. SHR directly regulates the expression of microRNA165/6, which degrades the PHB and genes for other class III HD-ZIP transcription factors and establishes their gradient in the stele. In shr mutants, PHB exists in a high concentration throughout the stele in the RAM. A high concentration of PHB in shr stele suppresses root meristem activity by modulating type B Arabidopsis Response Regulator (B-ARR) activity.
To discover novel factors involved in the SHR-mediated root growth program, we mutagenized shr-2 mutants with ethane methyl sulfonate (EMS). The lines of which roots grew longer than shr-2 roots were selected as shr suppressors of shr (ssh). Among those, we found that shr ssh206 and shr ssh80 have mutations in the same gene, HAWAIIAN SKIRT (HWS, AT3G61590), and followed up for further studies.
The root length and meristem size of shr ssh206 and shr ssh80 are significantly longer than those of the shr. But QC is not recovered completely. Allelism tests revealed that ssh206 and ssh80 are different alleles of mutations on the same HWS gene. Thus, we designate shr ssh206 as shr-2 hws-3, and shr ssh80 as shr-2 hws-4.
HWS is expressed in the root cap and in the pericycle of the differentiation zone. Cytokinin marker expression analysis in the shr-2 hws-3 and shr-2 hws-4 indicates that the meristem recovery of shr hws is not from the recovery of cytokinin signaling. Thus, further research is required to unveil how HWS is involved in the root meristem regulation together with SHR.
Language
English
URI
https://hdl.handle.net/10371/131589
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