| Budget Amount *help |
¥115,500,000 (Direct Cost: ¥115,500,000)
Fiscal Year 2009: ¥22,500,000 (Direct Cost: ¥22,500,000)
Fiscal Year 2008: ¥22,500,000 (Direct Cost: ¥22,500,000)
Fiscal Year 2007: ¥23,500,000 (Direct Cost: ¥23,500,000)
Fiscal Year 2006: ¥23,500,000 (Direct Cost: ¥23,500,000)
Fiscal Year 2005: ¥23,500,000 (Direct Cost: ¥23,500,000)
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| Research Abstract |
Iron is essential for most living organisms and is required for normal plant growth. We identified two novel cis-acting elements, IDE1 and IDE2, in the promoter of iron-deficiency-inducible IDS2 gene and two rice transcription factors, IDEF1 (IDE-binding factor 1) and IDEF2, which specifically bind to IDE1 and IDE2, respectively. IDEF1 efficiently binds to the CATGC sequence within IDE1. IDEF1 transcripts are constitutively present in rice roots and leaves. Transgenic rice plants expressing IDEF1 tolerate iron deficiency in calcareous soil. Expression analysis of these transgenic plants revealed that IDEF1 positively regulates iron-deficiency-induced genes, including the ferrous iron transporter gene OsIRT1 and the iron-deficiency-induced transcription factor gene OsIRO2. OsIRO2 regulates the expression of various Fe-deficiency-inducible genes including those for phytosiderophore biosynthesis. IDEF2 recognizes CA[A/C]G[T/C][T/C/A][T/C/A] within IDE2. IDEF2 transcripts are constitutively present in rice roots and leaves. Microarray analysis showed that IDEF2 is involved in the regulation of Fe-deficiency-inducible genes, including the Fe(II)-nicotianamine transporter gene OsYSL2. 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.
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