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Type: Journal article
Title: High-affinity nitrate transport in roots of Arabidopsis depends on expression of the NAR2-like gene AtNRT3.1
Author: Okamoto, M.
Kumar, A.
Li, W.
Wang, Y.
Siddiqi, M.
Crawford, N.
Glass, A.
Citation: Plant Physiology, 2006; 140(3):1036-1046
Publisher: Amer Soc Plant Physiologists
Issue Date: 2006
ISSN: 0032-0889
Statement of
Mamoru Okamoto, Anshuman Kumar, Wenbin Li, Ye Wang, M. Yaeesh Siddiqi, Nigel M. Crawford and Anthony D.M. Glass
Abstract: The NAR2 protein of Chlamydomonas reinhardtii has no known transport activity yet it is required for high-affinity nitrate uptake. Arabidopsis (Arabidopsis thaliana) possesses two genes, AtNRT3.1 and AtNRT3.2, that are similar to the C. reinhardtii NAR2 gene. AtNRT3.1 accounts for greater than 99% of NRT3 mRNA and is induced 6-fold by nitrate. AtNRT3.2 was expressed constitutively at a very low level and did not compensate for the loss of AtNRT3.1 in two Atnrt3.1 mutants. Nitrate uptake by roots and nitrate induction of gene expression were analyzed in two T-DNA mutants, Atnrt3.1-1 and Atnrt3.1-2, disrupted in the AtNRT3.1 promoter and coding regions, respectively, in 5-week-old plants. Nitrate induction of the nitrate transporter genes AtNRT1.1 and AtNRT2.1 was reduced in Atnrt3.1 mutant plants, and this reduced expression was correlated with reduced nitrate concentrations in the tissues. Constitutive high-affinity influx was reduced by 34% and 89%, respectively, in Atnrt3.1-1 and Atnrt3.1-2 mutant plants, while high-affinity nitrate-inducible influx was reduced by 92% and 96%, respectively, following induction with 1 mm KNO(3) after 7 d of nitrogen deprivation. By contrast, low-affinity influx appeared to be unaffected. Thus, the constitutive high-affinity influx and nitrate-inducible high-affinity influx (but not the low-affinity influx) of higher plant roots require a functional AtNRT3 (NAR2) gene.
Keywords: Arabidopsis
Plant Roots
Anion Transport Proteins
Arabidopsis Proteins
Sequence Alignment
Ion Transport
Amino Acid Sequence
Multigene Family
Molecular Sequence Data
Rights: © 2006 American Society of Plant Biologists
DOI: 10.1104/pp.105.074385
Published version:
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