The Arabidopsis Nitrate Transporter NRT1.8 Functions in Nitrate Removal from the Xylem Sap and Mediates Cadmium Tolerance

被引：346

作者：

Li, Jian-Yong ^{[1
]}

Fu, Yan-Lei ^{[1
]}

Pike, Sharon M. ^{[2
,3
]}

Bao, Juan ^{[1
]}

Tian, Wang ^{[4
]}

Zhang, Yu ^{[1
]}

Chen, Chun-Zhu ^{[1
]}

Zhang, Yi ^{[1
]}

Li, Hong-Mei ^{[1
]}

Huang, Jing ^{[1
]}

Li, Le-Gong ^{[4
]}

Schroeder, Julian I. ^{[5
,6
]}

Gassmann, Walter ^{[2
,3
]}

Gonga, Ji-Ming ^{[1
]}

机构：

[1] Chinese Acad Sci, Natl Key Lab Plant Mol Genet, Inst Plant Physiol & Ecol, Shanghai Inst Biol Sci, Shanghai 200032, Peoples R China

[2] Univ Missouri, Div Plant Sci, CS Bond Life Sci Ctr, Columbia, MO 65211 USA

[3] Univ Missouri, Interdisciplinary Plant Grp, Columbia, MO 65211 USA

[4] Capital Normal Univ, Coll Life Sci, Beijing 100037, Peoples R China

[5] Univ Calif San Diego, Div Biol Sci, La Jolla, CA 92093 USA

[6] Univ Calif San Diego, Ctr Mol Genet, Cell & Dev Biol Sect, La Jolla, CA 92093 USA

来源：

PLANT CELL | 2010年 / 22卷 / 05期

基金：

美国国家科学基金会;

关键词：

LONG-DISTANCE TRANSPORT; HIGHER-PLANTS; GENE-EXPRESSION; THIOL-PEPTIDES; SHOOT; ROOT; ENCODES; CHL1; PHYTOCHELATINS; ACCUMULATION;

D O I：

10.1105/tpc.110.075242

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Long-distance transport of nitrate requires xylem loading and unloading, a successive process that determines nitrate distribution and subsequent assimilation efficiency. Here, we report the functional characterization of NRT1.8, a member of the nitrate transporter (NRT1) family in Arabidopsis thaliana. NRT1.8 is upregulated by nitrate. Histochemical analysis using promoter-beta-glucuronidase fusions, as well as in situ hybridization, showed that NRT1.8 is expressed predominantly in xylem parenchyma cells within the vasculature. Transient expression of the NRT1.8: enhanced green fluorescent protein fusion in onion epidermal cells and Arabidopsis protoplasts indicated that NRT1.8 is plasma membrane localized. Electrophysiological and nitrate uptake analyses using Xenopus laevis oocytes showed that NRT1.8 mediates low-affinity nitrate uptake. Functional disruption of NRT1.8 significantly increased the nitrate concentration in xylem sap. These data together suggest that NRT1.8 functions to remove nitrate from xylem vessels. Interestingly, NRT1.8 was the only nitrate assimilatory pathway gene that was strongly upregulated by cadmium (Cd2+) stress in roots, and the nrt1.8-1 mutant showed a nitrate-dependent Cd2+-sensitive phenotype. Further analyses showed that Cd2+ stress increases the proportion of nitrate allocated to wildtype roots compared with the nrt1.8-1 mutant. These data suggest that NRT1.8-regulated nitrate distribution plays an important role in Cd2+ tolerance.

引用

页码：1633 / 1646

页数：14

共 55 条

[1] THE PARTITIONING OF NITRATE ASSIMILATION BETWEEN ROOT AND SHOOT OF HIGHER-PLANTS [J].