The FRD3-mediated efflux of citrate into the root vasculature is necessary for efficient iron translocation.
TLDR
In this paper, it was shown that FRD3 effluxes citrate into the root vasculature, a process important for the translocation of iron to the leaves, as well as confirm previous reports suggesting that iron moves through the xylem as a ferric-citrate complex.Abstract:
Iron, despite being an essential micronutrient, becomes toxic if present at high levels. As a result, plants possess carefully regulated mechanisms to acquire iron from the soil. The ferric reductase defective3 (frd3) mutant of Arabidopsis (Arabidopsis thaliana) is chlorotic and exhibits constitutive expression of its iron uptake responses. Consequently, frd3 mutants overaccumulate iron; yet, paradoxically, the frd3 phenotypes are due to a reduction in the amount of iron present inside frd3 leaf cells. The FRD3 protein belongs to the multidrug and toxin efflux family, members of which are known to export low-Mr organic molecules. We therefore hypothesized that FRD3 loads an iron chelator necessary for the correct distribution of iron throughout the plant into the xylem. One such potential chelator is citrate. Xylem exudate from frd3 plants contains significantly less citrate and iron than the exudate from wild-type plants. Additionally, supplementation of growth media with citrate rescues the frd3 phenotypes. The ectopic expression of FRD3-GFP results in enhanced tolerance to aluminum in Arabidopsis roots, a hallmark of organic acid exudation. Consistent with this result, approximately 3 times more citrate was detected in root exudate from plants ectopically expressing FRD3-GFP. Finally, heterologous studies in Xenopus laevis oocytes reveal that FRD3 mediates the transport of citrate. These results all strongly support the hypothesis that FRD3 effluxes citrate into the root vasculature, a process important for the translocation of iron to the leaves, as well as confirm previous reports suggesting that iron moves through the xylem as a ferric-citrate complex. Our results provide additional answers to long-standing questions about iron chelation in the vasculature and organic acid transport.read more
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Biofortification of crops with seven mineral elements often lacking in human diets--iron, zinc, copper, calcium, magnesium, selenium and iodine.
TL;DR: In this paper, the authors review aspects of soil science, plant physiology and genetics underpinning crop bio-fortification strategies, as well as agronomic and genetic approaches currently taken to biofortify food crops with the mineral elements most commonly lacking in human diets: iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), iodine (I) and selenium (Se).
Journal ArticleDOI
Heavy metal hyperaccumulating plants: how and why do they do it? And what makes them so interesting?
TL;DR: An overview of literature discussing the phytoremediation capacity of hyperaccumulators to clean up soils contaminated with heavy metals and the possibility of using these plants in phytomining is presented.
Journal ArticleDOI
Iron Uptake, Translocation, and Regulation in Higher Plants
TL;DR: Key molecular components-including transporters, enzymes, and chelators-have been clarified for both strategies of reduction and chelation, and many of these components are now thought to also function inside the plant to facilitate internal iron transport.
Journal ArticleDOI
Molecular mechanisms of metal hyperaccumulation in plants
Abstract: Contents
Summary 759
I. Hyperaccumulation: the phenomenon 759
II. Macroevolution of hyperaccumulation 760
III. Microevolution of hyperaccumulation: variation within hyperaccumulator species 760
IV. Genetic analysis of trace metal accumulation and tolerance 761
V. Mechanisms of trace metal accumulation 762
VI. General discussion and research perspectives 769
Acknowledgements 772
References 772
Summary
Metal hyperaccumulator plants accumulate and detoxify extraordinarily high concentrations of metal ions in their shoots. Metal hyperaccumulation is a fascinating phenomenon, which has interested scientists for over a century. Hyperaccumulators constitute an exceptional biological material for understanding mechanisms regulating plant metal homeostasis as well as plant adaptation to extreme metallic environments. Our understanding of metal hyperaccumulation physiology has recently increased as a result of the development of molecular tools. This review presents key aspects of our current understanding of plant metal – in particular cadmium (Cd), nickel (Ni) and zinc (Zn) – hyperaccumulation.
Journal ArticleDOI
Plant and microbial strategies to improve the phosphorus efficiency of agriculture
Alan Richardson,Alan Richardson,Jonathan P. Lynch,Peter R. Ryan,Emmanuel Delhaize,F. Andrew Smith,Sally E. Smith,Paul R. Harvey,Megan H. Ryan,Erik J. Veneklaas,Hans Lambers,Astrid Oberson,Richard A. Culvenor,Richard J. Simpson,Richard J. Simpson +14 more
TL;DR: Evidence that more P-efficient plants can be developed by modifying root growth and architecture, through manipulation of root exudates or by managing plant-microbial associations such as arbuscular mycorrhizal fungi and microbial inoculants is critically reviewed.
References
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Floral dip: a simplified method for Agrobacterium-mediated transformation of Arabidopsis thaliana
Steven J. Clough,Andrew F. Bent +1 more
TL;DR: The modified method should facilitate high-throughput transformation of Arabidopsis for efforts such as T-DNA gene tagging, positional cloning, or attempts at targeted gene replacement.
Journal ArticleDOI
IRT1, an Arabidopsis Transporter Essential for Iron Uptake from the Soil and for Plant Growth
Grégory Vert,Natasha Grotz,Fabienne Dédaldéchamp,Frédéric Gaymard,Mary Lou Guerinot,Jean-François Briat,Catherine Curie +6 more
TL;DR: Genetic evidence is presented that IRT1 is essential for the uptake of iron from the soil, and it is shown that I RT1 is expressed in the external cell layers of the root, specifically in response to iron starvation.
Journal ArticleDOI
A novel iron-regulated metal transporter from plants identified by functional expression in yeast
TL;DR: In Arabidopsis, IRT1 is expressed in roots, is induced by iron deficiency, and has altered regulation in plant lines bearing mutations that affect the iron uptake system, providing the first molecular insight into iron transport by plants.
Journal ArticleDOI
A ferric-chelate reductase for iron uptake from soils
TL;DR: The isolation of FRO2 has implications for the generation of crops with improved nutritional quality and increased growth in iron-deficient soils and for the treatment of iron deficiency in plants.
Journal ArticleDOI
Aluminum Tolerance in Wheat (Triticum aestivum L.) (II. Aluminum-Stimulated Excretion of Malic Acid from Root Apices)
TL;DR: There was a consistent correlation of Al tolerance with high rates of malic acid excretion stimulated by Al in a population of seedlings segregating for Al tolerance, consistent with the hypothesis that the Alt1 locus in wheat encodes an Al tolerance mechanism based on Al-stimulated excretion ofmalic acid.
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