title: Root-secreted nicotianamine from Arabidopsis halleri facilitates zinc hypertolerance by regulating zinc bioavailability.
abstract: Hyperaccumulators tolerate and accumulate extraordinarily high concentrations of heavy metals. Content of the metal chelator nicotianamine (NA) in the root of zinc hyperaccumulator Arabidopsis halleri is elevated compared with nonhyperaccumulators, a trait that is considered to be one of the markers of a hyperaccumulator. Using metabolite-profiling analysis of root secretions, we found that excess zinc treatment induced secretion of NA in A. halleri roots compared with the nonhyperaccumulator Arabidopsis thaliana. Metal speciation analysis further revealed that the secreted NA forms a stable complex with Zn(II). Supplying NA to a nonhyperaccumulator species markedly increased plant zinc tolerance by decreasing zinc uptake. Therefore, NA secretion from A. halleri roots facilitates zinc hypertolerance through forming a Zn(II)-NA complex outside the roots to achieve a coordinated zinc uptake rate into roots. Secretion of NA was also found to be responsible for the maintenance of iron homeostasis under excess zinc. Together our results reveal root-secretion mechanisms associated with hypertolerance and hyperaccumulation.
authors.affiliation: Agricultural Biotechnology Research Center (M.T., K.-C.Y.) and Institute of Earth Sciences (S.-C.Y., D.-C.L.), Academia Sinica, Taipei 115, Taiwan;Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica and National Chung-Hsing University, Taipei 115, Taiwan (M.T., K.-C.Y.); andGraduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung 250, Taiwan (M.T. and K.-C.Y.).
authors.forename: Munkhtsetseg
authors.initials: M
authors.lastname: Tsednee
authors.affiliation: Agricultural Biotechnology Research Center (M.T., K.-C.Y.) and Institute of Earth Sciences (S.-C.Y., D.-C.L.), Academia Sinica, Taipei 115, Taiwan;Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica and National Chung-Hsing University, Taipei 115, Taiwan (M.T., K.-C.Y.); andGraduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung 250, Taiwan (M.T. and K.-C.Y.).
authors.forename: Shun-Chung
authors.initials: SC
authors.lastname: Yang
authors.affiliation: Agricultural Biotechnology Research Center (M.T., K.-C.Y.) and Institute of Earth Sciences (S.-C.Y., D.-C.L.), Academia Sinica, Taipei 115, Taiwan;Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica and National Chung-Hsing University, Taipei 115, Taiwan (M.T., K.-C.Y.); andGraduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung 250, Taiwan (M.T. and K.-C.Y.).
authors.forename: Der-Chuen
authors.initials: DC
authors.lastname: Lee
authors.affiliation: Agricultural Biotechnology Research Center (M.T., K.-C.Y.) and Institute of Earth Sciences (S.-C.Y., D.-C.L.), Academia Sinica, Taipei 115, Taiwan;Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, Academia Sinica and National Chung-Hsing University, Taipei 115, Taiwan (M.T., K.-C.Y.); andGraduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung 250, Taiwan (M.T. and K.-C.Y.) kcyeh@gate.sinica.edu.tw.
authors.forename: Kuo-Chen
authors.identifier: http://orcid.org/0000-0002-3791-3423
authors.initials: KC
authors.lastname: Yeh
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000378:metabolism* / Q000502:physiology; D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001682:Biological Availability; D018517:Plant Roots / Q000378:metabolism*; D015032:Zinc / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: C082893:nicotianamine; D001383:Azetidinecarboxylic Acid; D015032:Zinc