IRT1, an Arabidopsis transporter essential for iron uptake from the soil and for plant growth.
Plants are the principal source of iron in most diets, yet iron availability often limits plant growth. In response to iron deficiency, Arabidopsis roots induce the expression of the divalent cation transporter IRT1. Here, we present genetic evidence that IRT1 is essential for the uptake of iron from the soil. An Arabidopsis knockout mutant in IRT1 is chlorotic and has a severe growth defect in soil, leading to death. This defect is rescued by the exogenous application of iron. The mutant plants do not take up iron and fail to accumulate other divalent cations in low-iron conditions. IRT1-green fluorescent protein fusion, transiently expressed in culture cells, localized to the plasma membrane. We also show, through promoter::beta-glucuronidase analysis and in situ hybridization, that IRT1 is expressed in the external cell layers of the root, specifically in response to iron starvation. These results clearly demonstrate that IRT1 is the major transporter responsible for high-affinity metal uptake under iron deficiency.
Vert
Grégory
G
Biochimie et Physiologie Moléculaire des Plantes, Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5004), Université Montpellier II, 2 Place Viala, F-34060 Montpellier Cedex 1, France.
Grotz
Natasha
N
Dédaldéchamp
Fabienne
F
Gaymard
Frédéric
F
Guerinot
Mary Lou
ML
Briat
Jean-François
JF
Curie
Catherine
C
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D001692:Biological Transport; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism; D017931:DNA Primers; D038181:FMN Reductase; D017353:Gene Deletion; D005804:Genes, Lethal; D017343:Genes, Plant; D049452:Green Fluorescent Proteins; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012987:Soil
D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D002413:Cations, Divalent; D017931:DNA Primers; C099651:IRT1 protein, Arabidopsis; D008164:Luminescent Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012987:Soil; D049452:Green Fluorescent Proteins; D007501:Iron; D038181:FMN Reductase; D009247:NADH, NADPH Oxidoreductases; C023903:ferric citrate iron reductase