Arabidopsis IRT2 cooperates with the high-affinity iron uptake system to maintain iron homeostasis in root epidermal cells.
Iron is an essential nutrient for all organisms but toxic when present in excess. Consequently, plants carefully regulate their iron uptake, dependent on the FRO2 ferric reductase and the IRT1 transporter, to control its homeostasis. Arabidopsis IRT2 gene, whose expression is induced in root epidermis upon iron deprivation, was shown to encode a functional iron/zinc transporter in yeast, and proposed to function in iron acquisition from the soil. In this study, we demonstrate that, unlike its close homolog IRT1, IRT2 is not involved in iron absorption from the soil since overexpression of IRT2 does not rescue the iron uptake defect of irt1-1 mutant and since a null irt2 mutant shows no chlorosis in low iron. Consistently, an IRT2-green fluorescent fusion protein, transiently expressed in culture cells, localizes to intracellular vesicles. However, IRT2 appears strictly co-regulated with FRO2 and IRT1, supporting the view that IRT2 is an integral component of the root response to iron deficiency in root epidermal cells. We propose a model where IRT2 likely prevents toxicity from IRT1-dependent iron fluxes in epidermal cells, through compartmentalization.
Vert
Grégory
G
Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, CNRS UMR 5004, 2 place Viala, 34060, Montpellier Cedex 1, France.
Barberon
Marie
M
Zelazny
Enric
E
Séguéla
Mathilde
M
Briat
Jean-François
JF
Curie
Catherine
C
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D038181:FMN Reductase / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009154:Mutation; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C099651:IRT1 protein, Arabidopsis; C434452:IRT2 protein, Arabidopsis; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase