Arabidopsis Nitrate Transporter NRT1.9 Is Important in Phloem Nitrate Transport

被引：173

作者：

Wang, Ya-Yun ^{[1
,2
,3
]}

Tsay, Yi-Fang ^{[1
,2
,3
]}

机构：

[1] Natl Yang Ming Univ, Dept Life Sci, Taipei 112, Taiwan

[2] Natl Yang Ming Univ, Inst Genome Sci, Taipei 112, Taiwan

[3] Acad Sinica, Inst Mol Biol, Taipei 115, Taiwan

来源：

PLANT CELL | 2011年 / 23卷 / 05期

关键词：

LONG-DISTANCE TRANSPORT; FUNCTIONAL-CHARACTERIZATION; RICINUS-COMMUNIS; PLANT-RESPONSES; WHOLE-PLANT; XYLEM SAP; GENE; ASSIMILATION; THALIANA; NITROGEN;

D O I：

10.1105/tpc.111.083618

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：

This study of the Arabidopsis thaliana nitrate transporter NRT1.9 reveals an important function for a NRT1 family member in phloem nitrate transport. Functional analysis in Xenopus laevis oocytes showed that NRT1.9 is a low-affinity nitrate transporter. Green fluorescent protein and beta-glucuronidase reporter analyses indicated that NRT1.9 is a plasma membrane transporter expressed in the companion cells of root phloem. In nrt1.9 mutants, nitrate content in root phloem exudates was decreased, and downward nitrate transport was reduced, suggesting that NRT1.9 may facilitate loading of nitrate into the root phloem and enhance downward nitrate transport in roots. Under high nitrate conditions, the nrt1.9 mutant showed enhanced root-to-shoot nitrate transport and plant growth. We conclude that phloem nitrate transport is facilitated by expression of NRT1.9 in root companion cells. In addition, enhanced root-to-shoot xylem transport of nitrate in nrt1.9 mutants points to a negative correlation between xylem and phloem nitrate transport.

引用

页码：1945 / 1957

页数：13

共 78 条

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