Mutation of the Arabidopsis NRT1.5 nitrate transporter causes defective root-to-shoot nitrate transport
Journal
Plant Cell
Journal Volume
20
Journal Issue
9
Pages
2514
Date Issued
2008-09-01
Author(s)
Lin, Shan Hua
Kuo, Hui Fen
Canivenc, Geneviève
Lin, Choun Sea
Lepetit, Marc
Hsu, Po Kai
Tillard, Pascal
Lin, Huey G.
Tsai, Chyn Bey
Gojon, Alain
Tsay, Yi Fang
Abstract
Little is known about the molecular and regulatory mechanisms of long-distance nitrate transport in higher plants. NRT1.5 is one of the 53 Arabidopsis thaliana nitrate transporter NRT1 (Peptide Transporter PTR) genes, of which two members, NRT1.1 (CHL1 for Chlorate resistant 1) and NRT1.2, have been shown to be involved in nitrate uptake. Functional analysis of cRNA-injected Xenopus laevis oocytes showed that NRT1.5 is a low-affinity, pH-dependent bidirectional nitrate transporter. Subcellular localization in plant protoplasts and in planta promoter-β-glucuronidase analysis, as well as in situ hybridization, showed that NRT1.5 is located in the plasma membrane and is expressed in root pericycle cells close to the xylem. Knockdown or knockout mutations of NRT1.5 reduced the amount of nitrate transported from the root to the shoot, suggesting that NRT1.5 participates in root xylem loading of nitrate. However, root-to-shoot nitrate transport was not completely eliminated in the NRT1.5 knockout mutant, and reduction of NRT1.5 in the nrt1.1 background did not affect root-to-shoot nitrate transport. These data suggest that, in addition to that involving NRT1.5, another mechanism is responsible for xylem loading of nitrate. Further analyses of the nrt1.5 mutants revealed a regulatory loop between nitrate and potassium at the xylem transport step. © 2008 American Society of Plant Biologists.
SDGs
Other Subjects
Arabidopsis; Arabidopsis thaliana; Embryophyta; Xenopus laevis
Publisher
AMER SOC PLANT BIOLOGISTS
Type
journal article
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