transcription factor IDEF1 regulates the response to and tolerance of iron deficiency in plants

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 48; pp. 19150 - 19155
• Main Authors: Kobayashi, Takanori, Ogo, Yuko, Itai, Reiko Nakanishi, Nakanishi, Hiromi, Takahashi, Michiko, Mori, Satoshi, Nishizawa, Naoko K
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 27.11.2007; National Acad Sciences
• Subjects: binding sites; Biological Sciences; Calcareous soils; Cauliflower mosaic virus; Caulimovirus - genetics; Cells, Cultured - metabolism; gene expression; gene expression regulation; Gene Expression Regulation, Plant; Genes; Genes, Reporter; Genes, Synthetic; Helix-Loop-Helix Motifs; IDEF1 gene; Immunity, Innate - genetics; Iron; Iron - metabolism; iron deficiency-responsive cis-acting element; Leaves; messenger RNA; Nicotiana - genetics; nutrient deficiencies; Onions - cytology; Oryza - genetics; Oryza - physiology; Oryza sativa; Plant Diseases - genetics; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - physiology; Plant roots; Plant Roots - metabolism; Plants; Plants, Genetically Modified; promoter regions; Rice; roots; Soils; Tobacco; transcription (genetics); Transcription factors; Transcriptional Activation; Transgenic plants; Viruses; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0707010104

Iron is essential for most living organisms and is often the major limiting nutrient for normal growth. Plants induce iron utilization systems under conditions of low iron availability, but the molecular mechanisms of gene regulation under iron deficiency remain largely unknown. We identified the rice transcription factor IDEF1, which specifically binds the iron deficiency-responsive cis-acting element IDE1. IDEF1 belongs to an uncharacterized branch of the plant-specific transcription factor family ABI3/VP1 and exhibits the sequence recognition property of efficiently binding to the CATGC sequence within IDE1. IDEF1 transcripts are constitutively present in rice roots and leaves. Transgenic tobacco plants expressing IDEF1 under the control of the constitutive cauliflower mosaic virus 35S promoter transactivate IDE1-mediated expression only in iron-deficient roots. Transgenic rice plants expressing an introduced IDEF1 exhibit substantial tolerance to iron deficiency in both hydroponic culture and calcareous soil. IDEF1 overexpression leads to the enhanced expression of the iron deficiency-induced transcription factor gene OsIRO2, suggesting the presence of a sequential gene regulatory network. These findings reveal cis element/trans factor interactions that are functionally linked to the iron deficiency response. Manipulation of IDEF1 also provides another approach for producing crops tolerant of iron deficiency to enhance food and biomass production in calcareous soils.