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

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

AtbHLH29 of Arabidopsis, encoding a bHLH protein, reveals a high similarity to the tomato FER which is proposed as a transcriptional regulator involved in controlling the iron deficiency responses and the iron uptake in tomato. For identification of its biological functions, AtbHLH29 was introduced into the genome of the tomato FER mutant T3238fer mediated by Agrobacterium tumefaciencs. Transgenic plants were regenerated and the stable integration of AtbHLH29 into their genomes was confirmed by Southern hybridization. Molecular analysis demonstrated that expression of the exogenous AtbHLH29 of Arabidopsis in roots of the FER mutant T3238fer enabled to complement the defect functions of FER. The transgenic plants regained the ability to activate the whole iron deficiency responses and showed normal growth as the wild type under iron-limiting stress. Our transformation data demonstrate that AtbHLH29 is a functional ortholog of the tomato FER and can completely replace FER in controlling the effective iron acquisition in tomato. Except of iron, FER protein was directly or indirectly involved in manganese homeostasis due to that loss functions of FER in T3238fer resulted in strong reduction of Mn content in leaves and the defect function on Mn accumulation in leaves was complemented by expression of AtbHLH29 in the transgenic plants. Identification of the similar biological functions of FER and AtbHLH29, which isolated from two systematically wide-diverged "strategy I" plants, suggests that FER might be a universal gene presented in all strategy I plants in controlling effective iron acquisition system in roots.
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PMID:AtbHLH29 of Arabidopsis thaliana is a functional ortholog of tomato FER involved in controlling iron acquisition in strategy I plants. 1611 51

Iron is an essential and commonly limited nutrient for plants. To increase the uptake of iron during times of low iron supply, plants, except the grasses, activate a set of physiological and morphological responses in their roots that include iron reduction, soil acidification, Fe(II) transport and proliferation of root hairs. It is not known how root cells sense and transduce the changes that occur after the onset of iron deficiency. This work presents evidence that nitric oxide (NO) is produced rapidly in the root epidermis of tomato plants (Solanum lycopersicum) that are grown in iron-deficient conditions. The scavenging of NO prevented iron-deficiency-induced upregulation of the basic helix-loop-helix transcription factor FER, the ferric-chelate reductase LeFRO1 and the Fe(II) transporter LeIRT1 genes. On the other hand, exogenous application of the NO donor S-nitrosoglutathione enhanced the accumulation of FER, LeFRO1 and LeIRT1 mRNA in roots of iron-deficient plants. The activity of the root ferric-chelate reductase and the proliferation of root hairs induced by iron deficiency were stimulated by NO supplementation and suppressed by NO scavenging. Nitric oxide was ineffective in inducing iron-deficiency responses in the tomato fer mutant, which indicates that the FER protein is necessary to mediate the action of NO. Furthermore, NO supplementation improved plant growth under low iron supply, which suggests that NO is a key component of the regulatory mechanisms that control iron uptake and homeostasis in plants. In summary, the results of this investigation indicate that an increase in NO production is an early response of roots to iron deprivation that contributes to the improvement of iron availability by (i) modulating the expression of iron uptake-related genes and (ii) regulating the physiological and morphological adaptive responses of roots to iron-deficient conditions.
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PMID:Nitric oxide accumulation is required for molecular and physiological responses to iron deficiency in tomato roots. 1789 45