title: Metabolome analysis of Arabidopsis thaliana roots identifies a key metabolic pathway for iron acquisition.
abstract: Fe deficiency compromises both human health and plant productivity. Thus, it is important to understand plant Fe acquisition strategies for the development of crop plants which are more Fe-efficient under Fe-limited conditions, such as alkaline soils, and have higher Fe density in their edible tissues. Root secretion of phenolic compounds has long been hypothesized to be a component of the reduction strategy of Fe acquisition in non-graminaceous plants. We therefore subjected roots of Arabidopsis thaliana plants grown under Fe-replete and Fe-deplete conditions to comprehensive metabolome analysis by gas chromatography-mass spectrometry and ultra-pressure liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry. Scopoletin and other coumarins were found among the metabolites showing the strongest response to two different Fe-limited conditions, the cultivation in Fe-free medium and in medium with an alkaline pH. A coumarin biosynthesis mutant defective in ortho-hydroxylation of cinnamic acids was unable to grow on alkaline soil in the absence of Fe fertilization. Co-cultivation with wild-type plants partially rescued the Fe deficiency phenotype indicating a contribution of extracellular coumarins to Fe solubilization. Indeed, coumarins were detected in root exudates of wild-type plants. Direct infusion mass spectrometry as well as UV/vis spectroscopy indicated that coumarins are acting both as reductants of Fe(III) and as ligands of Fe(II).
authors: Department of Plant Physiology, University of Bayreuth, Bayreuth, Germany.
authors: Holger
authors: H
authors: Schmidt
authors: Department of Plant Physiology, University of Bayreuth, Bayreuth, Germany.
authors: Carmen
authors: C
authors: Günther
authors: Department of Plant Physiology, University of Bayreuth, Bayreuth, Germany.
authors: Michael
authors: M
authors: Weber
authors: Department of Organic Chemistry, University of Bayreuth, Bayreuth, Germany.
authors: Cornelia
authors: C
authors: Spörlein
authors: Department of Organic Chemistry, University of Bayreuth, Bayreuth, Germany.
authors: Sebastian
authors: S
authors: Loscher
authors: Department of Stress and Developmental Biology, Leibniz Institute of Plant Biochemistry, Halle/Saale, Germany.
authors: Christoph
authors: C
authors: Böttcher
authors: Department of Organic Chemistry, University of Bayreuth, Bayreuth, Germany; Bayreuth Center for Molecular Biosciences, University of Bayreuth, Bayreuth, Germany.
authors: Rainer
authors: R
authors: Schobert
authors: Department of Plant Physiology, University of Bayreuth, Bayreuth, Germany; Bayreuth Center for Molecular Biosciences, University of Bayreuth, Bayreuth, Germany.
authors: Stephan
authors: S
authors: Clemens
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D002934:Cinnamates / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D007501:Iron / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D055442:Metabolome; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism*; D012603:Scopoletin / Q000378:metabolism; D012987:Soil / Q000737:chemistry
chemical_list: D002934:Cinnamates; D012987:Soil; C029010:cinnamic acid; D007501:Iron; D012603:Scopoletin