2014 Fiscal Year Annual Research Report
| Project/Area Number |
13J01792
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| Research Institution | Osaka University |
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Principal Investigator |
チヤン イェ 大阪大学, 理学研究科, 特別研究員(DC1)
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| Project Period (FY) |
2013-04-01 – 2016-03-31
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| Keywords | Plant development / Transcription factor / Lateral root development / Cell identity |
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| Outline of Annual Research Achievements |
I have been screening for the key transcription factors(TF) that determine cell-type specificities and have established an efficient screening system.
Over my previous study, I had been working on gene No.17. Repression of No.17's target genes by No.17-SRDX causes loss of XPP-specific GFP expression in and inhibits lateral root formation. Activation of No.17’s target genes by No.17-VP16 caused ectopic expression of XPP-specific GFP. However, No.17-overexpression phenotype is mild and the expression of No.17 is broad. No.17 belongs to the bHLH TF family, of which the proteins often dimerize to bind to DNA. So we looked into other bHLH TF with expression in XPP and found gene No.51.
Overexpression of gene No.51, which is specifically expressed in pericycle, causes ectopic expression of XPP-specific marker. In wild-type root from differentiation zone up, cell division occurs only in the XPP. When No.51 is overexpressed, root cells outside the pericycle also undergo cell division. No.51-SRDX caused loss of XPP marker expression and inhibits pericycle cell division and LR formation. Our results show that No.51 may be the key regulator of XPP cell identity, especially in the aspects of its competence to undergo cell division.
We have performed a Yeast-2-Hybrid Assay and confirmed an interaction between No.17 and No.51. It is possible that No.17 and No.51 form dimers to function.Ongoing studies on No.17, No.51, their knock-out mutants, their interactions, and their downstream target may serve to reveal the regulatory network that determines pericycle cell identity.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
This year as planned I have been focusing on the important candidate genes I have identified over the previous years of my study. I had been working on gene No.17. And though examining the genes related to No.17, I have identified another TF, No.51.
This year I have mainly worked on gene No.51. I have made transgenic lines of No.51-overexpression and No.51-SRDX in several different background, and I have obtained stable and consistent phenotypes. In No.51-overexpressing plant, instead of lateral roots, there are tutor-like structures on the primary root, which is a novel and very interesting phenotype. Using marker lines, I could show that No.51-overexpression caused ectopic cell division, which is a key feature for pericycle cells. I have made a translational fusion GFP marker line for No.51 and analysed its expression pattern during development stages and under hormone treatments. The expression pattern of no.51 also confirms that it has roles in regulating cell division activity in pericycle cells.
I am also working on several other genes related to No.17 or No.51. The preliminary results support our present interpretation on No.17 and No.51's functions and their interaction.
In conclusion, the study this year has been going on smoothly and I have got more than expected progress.
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| Strategy for Future Research Activity |
In the next year, I will continue focus on gene No.51. I will focus on the knockout mutant phenotypes of No.51, No.17 and other related genes. I will make multiple knockout mutants by crossing the single mutants of each gene since so far no single mutant showed any visible phenotype in root. To gain an overall view of the up-and down-regulation of gene expression in the No.51-overexpression and No.51-SRDX plant and to eventually identify No.51's direct downstream targets, plant materials are being prepared for a microarray analysis. Also, I am planning experiments such as BiFC assay to confirm the interaction between No.17 and No.51 in vivo. The expression of No.51 is down-regulated by auxin treatment, yet it positively regulate the expression of itself. There might be a complicated feed back loop regulation mechanism involved. And it will be interesting to address this question.
By completing these works, I may finally reveal a transcriptional regulation network that determine the pericycle cell identity.
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Research Products
(2 results)
