title: AtIRT1, the primary iron uptake transporter in the root, mediates excess nickel accumulation in Arabidopsis thaliana.
abstract: Nickel (Ni) is an essential nutrient for plants, but excessive amounts can be toxic. Ni competes with iron (Fe) in vivo, raising the possibility that Ni is competitively taken up via the Fe uptake system in plants. Here, we show evidence that AtIRT1, the primary Fe(2+) uptake transporter in the root, mediates Ni accumulation in Arabidopsis thaliana. In hydroponic cultures, excess Ni exposure increased Fe accumulation and the relative transcription level of AtIRT1 in roots, indicating that excess Ni induces AtIRT1 expression in roots. An Fe-deficient treatment increased Ni accumulation in plants, suggesting that excess Ni was absorbed via the Fe uptake system, which was induced by Fe starvation. Moreover, Ni accumulation under Fe-deficient conditions was markedly lower in AtIRT1-defective mutants than in the wild-type, Col-0. Furthermore, AtIRT1 showed Ni(2+) uptake activity in a yeast expression system. These data demonstrate that AtIRT1 transports Ni(2+) in roots, and strongly suggest that Ni accumulation is further accelerated by AtIRT1 that is expressed in response to excess Ni.
authors: Graduate School of Bioresources, Mie University, Kurimamachiya-cho 1577, Tsu, Mie, 514-8507 Japan.
authors: Sho
authors: S
authors: Nishida
authors: Chisato
authors: C
authors: Tsuzuki
authors: Aki
authors: A
authors: Kato
authors: Ayaka
authors: A
authors: Aisu
authors: Junko
authors: J
authors: Yoshida
authors: Takafumi
authors: T
authors: Mizuno
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018527:Hydroponics; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D009532:Nickel / Q000378:metabolism* / Q000633:toxicity; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C099651:IRT1 protein, Arabidopsis; D009532:Nickel; D007501:Iron