Overexpression of the FRO2 ferric chelate reductase confers tolerance to growth on low iron and uncovers posttranscriptional control

• Published in: Plant physiology (Bethesda) Vol. 133; no. 3; pp. 1102 - 1110
• Main Authors: Connolly, E.L, Campbell, N.H, Grotz, N, Prichard, C.L, Guerinot, M.L
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.11.2003; American Society of Plant Physiologists; The American Society for Plant Biologists
• Subjects: Adaptation, Physiological; Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Arabidopsis; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological and medical sciences; cadmium; Cation Transport Proteins; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Chelates; copper chelate reductase; drug effects; enzyme activity; enzymology; epidermis (plant); ferric chelate reductase; flowers; Flowers - enzymology; Flowers - genetics; FMN Reductase; FMN Reductase - genetics; FMN Reductase - metabolism; FR)2 protein; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; gene overexpression; genetics; Genetics, Genomics, and Molecular Evolution; growth & development; Iron; Iron - pharmacology; irt 1 protein; Messenger RNA; metabolism; Molecular Sequence Data; NADH or NADPH oxidoreductases; nucleotide sequences; pharmacology; Plant Epidermis; Plant Epidermis - enzymology; Plant Epidermis - genetics; Plant growth regulators; Plant physiology and development; plant proteins; plant response; Plant Roots; Plant Roots - enzymology; Plant Roots - genetics; plant stress; Plants; post-transcriptional RNA processing; RNA; RNA Processing, Post-Transcriptional; RNA Processing, Post-Transcriptional - drug effects; roots; transcription (genetics); Transgenic plants; transporters; Water and solutes. Absorption, translocation and permeability; Zinc; Zinc - pharmacology; Growth; Available nutrient; Gene overexpression; Iron; Inorganic element; Posttranscriptional modification; Arabidopsis thaliana; Regulation(control); Absorption; Cruciferae; Dicotyledones; Angiospermae; Carrier protein; Adaptation; Cadmium; Starvation; Nutrition; Enzyme; Deficiency; Tolerance; Nutrient uptake; Zinc; Heavy metal; Ferric-chelate reductase; Nutrient; Spermatophyta; Oxidoreductases; Experimental plant
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.103.025122

The Arabidopsis FRO2 gene encodes the low-iron-inducible ferric chelate reductase responsible for reduction of iron at the root surface. Here, we report that FRO2 and IRT1, the major transporter responsible for high-affinity iron uptake from the soil, are coordinately regulated at both the transcriptional and posttranscriptional levels. FRO2 and IRT1 are induced together following the imposition of iron starvation and are coordinately repressed following iron resupply. Steady-state mRNA levels of FRO2 and IRT1 are also coordinately regulated by zinc and cadmium. Like IRT1, FRO2 mRNA is detected in the epidermal cells of roots, consistent with its proposed role in iron uptake from the soil. FRO2 mRNA is detected at high levels in the roots and shoots of 35S-FRO2 transgenic plants. However, ferric chelate reductase activity is only elevated in the 35S-FRO2 plants under conditions of iron deficiency, indicating that FRO2 is subject to posttranscriptional regulation, as shown previously for IRT1. Finally, the 35S-FRO2 plants grow better on low iron as compared with wild-type plants, supporting the idea that reduction of ferric iron to ferrous iron is the rate-limiting step in iron uptake.