| Project/Area Number |
18380048
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plant nutrition/Soil science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
K.NISHIZAWA Naoko The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor (70156066)
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| Co-Investigator(Kenkyū-buntansha) |
NAKANISHI Hiromi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Assistant professor (80282698)
TAKAHASHI Michiko The University of Tokyo, Graduate School of Agricultural and Life Sciences, Assistant professor (90345182)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥16,850,000 (Direct Cost: ¥14,900,000、Indirect Cost: ¥1,950,000)
Fiscal Year 2007: ¥8,450,000 (Direct Cost: ¥6,500,000、Indirect Cost: ¥1,950,000)
Fiscal Year 2006: ¥8,400,000 (Direct Cost: ¥8,400,000)
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| Keywords | Plant growth physiology / Transcription factor |
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| Research Abstract |
Iron is essential for most living organisms and is required for normal plant growth. Plants induce iron utilization systems under conditions of low iron availability, but the molecular mechanisms of this gene regulation system remain largely unknown. The objective of this research was to clarify the regulation mechanism of iron deficiency responsive gene expression.
We previously analyzed the promoter region of the barley iron-deficiency-inducible IDS2 gene and identified the novel iron-deficiency-responsive cis-acting elements IDE1 and IDE2 (iron-deficiency-responsive element 1 and 2). In the present research, we identified a novel rice transcription factor, IDEF1, which specifically binds to IDE1.
IDEF1 belongs to an uncharacterized branch of the plant-specific transcription factor family ABI3/VP1 and efficiently binds to the CATGC sequence within IDE1. IDEF1 transcripts are constitutively present in rice roots and leaves. Transgenic rice plants expressing IDEF1 under the control of th
… More
e iron-deficiency-inducible IDS2 promoter tolerate iron deficiency in calcareous soil. Conversely, transgenic rice plants with repressed IDEF1 expression are susceptible to early stage iron deficiency in hydroponic culture. These results demonstrate that IDEF1 expression levels positively affect tolerance to iron deficiency at the early stage.
Expression analysis of these transgenic plants revealed that alteration of IDEF1 transcript levels affect the expression of many iron-deficiency-induced genes involved in iron uptake and utilization. The most pronounced was transactivation of OsIRT1, a ferrous transporter gene, and OsIRO2, an iron-deficiency-induced bHLH transcription factor gene. These data suggest the presence of a sequential gene regulatory network that functions via novel cis element/trans factor interactions to promote the iron-deficiency response. In conclusion, our results demonstrated that IDEF1 functions as a key component regulating the response to and tolerance of iron deficiency. These findings became a breakthrough in our understanding of iron homeostasis in plant. Less
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