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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Regulation of iron uptake is critical for plant survival. Although the activities responsible for reduction and transport of iron at the plant root surface have been described, the genes controlling these activities are largely unknown. We report the identification of the essential gene Fe-deficiency Induced Transcription Factor 1 (FIT1), which encodes a putative transcription factor that regulates iron uptake responses in Arabidopsis thaliana. Like the Fe(III) chelate reductase FRO2 and high affinity Fe(II) transporter IRT1, FIT1 mRNA is detected in the outer cell layers of the root and accumulates in response to iron deficiency. fit1 mutant plants are chlorotic and die as seedlings but can be rescued by the addition of supplemental iron, pointing to a defect in iron uptake. fit1 mutant plants accumulate less iron than wild-type plants in root and shoot tissues. Microarray analysis shows that expression of many (72 of 179) iron-regulated genes is dependent on FIT1. We demonstrate that FIT1 regulates FRO2 at the level of mRNA accumulation and IRT1 at the level of protein accumulation. We propose a new model for iron uptake in Arabidopsis where FRO2 and IRT1 are differentially regulated by FIT1.
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PMID:The essential basic helix-loop-helix protein FIT1 is required for the iron deficiency response. 1553 73

Root iron mobilization genes are induced by iron deficiency downstream of an unknown signaling mechanism. The FER gene, encoding a basic helix-loop-helix domain protein and putative transcription factor, is required for induction of iron mobilization genes in roots of tomato (Lycopersicon esculentum). To study upstream regulatory events of FER action, we examined the control of FER gene and FER protein expression in response to iron nutritional status. We analyzed expression of the FER gene and FER protein in wild-type plants, in mutant plants with defects in iron uptake regulation, and in 35S transgenic plants that overexpressed the FER gene. An affinity-purified antiserum directed against FER epitopes was produced that recognized FER protein in plant protein extracts. We found that the FER gene and FER protein were consistently down-regulated in roots after generous (100 mum, physiologically optimal) iron supply compared to low (0.1 mum) and sufficient (10 mum) iron supply. FER gene and FER protein expression were also occasionally down-regulated at sufficient compared to low iron supply. Analysis of FER protein expression in FER overexpression plants, as well as cellular protein localization studies, indicated that FER was down-regulated by high iron at the posttranscriptional level. The FER protein was targeted to plant nuclei and showed transcriptional activation in yeast (Saccharomyces cerevisiae). FER protein regulation in the iron accumulation mutant chloronerva indicated that FER protein expression was not directly controlled by signals derived from iron transport. We conclude that FER is able to affect transcription in the nucleus and its action is controlled by iron supply at multiple regulatory levels.
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PMID:Iron-mediated control of the basic helix-loop-helix protein FER, a regulator of iron uptake in tomato. 1569 40