OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) OA All Versions of this Article: 143/1/425    most recent pp.106.091223v2 pp.106.091223v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (19) Citing Articles via Google Scholar Google Scholar Articles by Li, W. Articles by Glass, A. D.M. Search for Related Content PubMed PubMed Citation Articles by Li, W. Articles by Glass, A. D.M. Agricola Articles by Li, W. Articles by Glass, A. D.M.

WHOLE PLANT AND ECOPHYSIOLOGY

Dissection of the AtNRT2.1:AtNRT2.2 Inducible High-Affinity Nitrate Transporter Gene Cluster^1,[OA]

Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T1Z4 (W.L., Y.W., Y.S., A.D.M.G.); and Department of Biology, University of California, La Jolla, California 92093–0116 (M.O., N.M.C.)

Using a new Arabidopsis (Arabidopsis thaliana) mutant (Atnrt2.1-nrt2.2) we confirm that concomitant disruption of NRT2.1 and NRT2.2 reduces inducible high-affinity transport system (IHATS) by up to 80%, whereas the constitutive high-affinity transport system (CHATS) was reduced by 30%. Nitrate influx via the low-affinity transport system (LATS) was unaffected. Shoot-to-root ratios were significantly reduced compared to wild-type plants, the major effect being upon shoot growth. In another mutant uniquely disrupted in NRT2.1 (Atnrt2.1), IHATS was reduced by up to 72%, whereas neither the CHATS nor the LATS fluxes were significantly reduced. Disruption of NRT2.1 in Atnrt2.1 caused a consistent and significant reduction of shoot-to-root ratios. IHATS influx and shoot-to-root ratios were restored to wild-type values when Atnrt2.1-nrt2.2 was transformed with a NRT2.1 cDNA isolated from Arabidopsis. Disruption of NRT2.2 in Atnrt2.2 reduced IHATS by 19% and this reduction was statistically significant only at 6 h after resupply of nitrate to nitrogen-deprived plants. Atnrt2.2 showed no significant reduction of CHATS, LATS, or shoot-to-root ratios. These results define NRT2.1 as the major contributor to IHATS. Nevertheless, when maintained on agar containing 0.25 mM KNO₃ as the sole nitrogen source, Atnrt2.1-nrt2.2 consistently exhibited greater stress and growth reduction than Atnrt2.1. Evidence from real-time PCR revealed that NRT2.2 transcript abundance was increased almost 3-fold in Atnrt2.1. These findings suggest that NRT2.2 normally makes only a small contribution to IHATS, but when NRT2.1 is lost, this contribution increases, resulting in a partial compensation.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Anthony D.M. Glass (aglass{at}interchange.ubc.ca).

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.106.091223

^* Corresponding author; e-mail aglass{at}interchange.ubc.ca; fax 604–822–6089.

Received October 11, 2006; accepted October 22, 2006; published November 3, 2006.

This article has been cited by other articles:

				S.-C. Fan, C.-S. Lin, P.-K. Hsu, S.-H. Lin, and Y.-F. Tsay The Arabidopsis Nitrate Transporter NRT1.7, Expressed in Phloem, Is Responsible for Source-to-Sink Remobilization of Nitrate PLANT CELL, September 1, 2009; 21(9): 2750 - 2761. [Abstract] [Full Text] [PDF]

				A. Almagro, S. H. Lin, and Y. F. Tsay Characterization of the Arabidopsis Nitrate Transporter NRT1.6 Reveals a Role of Nitrate in Early Embryo Development PLANT CELL, December 1, 2008; 20(12): 3289 - 3299. [Abstract] [Full Text] [PDF]

				S.-H. Lin, H.-F. Kuo, G. Canivenc, C.-S. Lin, M. Lepetit, P.-K. Hsu, P. Tillard, H.-L. Lin, Y.-Y. Wang, C.-B. Tsai, et al. Mutation of the Arabidopsis NRT1.5 Nitrate Transporter Causes Defective Root-to-Shoot Nitrate Transport PLANT CELL, September 1, 2008; 20(9): 2514 - 2528. [Abstract] [Full Text] [PDF]

				S. Kant, Y.-M. Bi, E. Weretilnyk, S. Barak, and S. J. Rothstein The Arabidopsis Halophytic Relative Thellungiella halophila Tolerates Nitrogen-Limiting Conditions by Maintaining Growth, Nitrogen Uptake, and Assimilation Plant Physiology, July 1, 2008; 147(3): 1168 - 1180. [Abstract] [Full Text] [PDF]

				S. Ruffel, S. Freixes, S. Balzergue, P. Tillard, C. Jeudy, M. L. Martin-Magniette, M. J. van der Merwe, K. Kakar, J. Gouzy, A. R. Fernie, et al. Systemic Signaling of the Plant Nitrogen Status Triggers Specific Transcriptome Responses Depending on the Nitrogen Source in Medicago truncatula Plant Physiology, April 1, 2008; 146(4): 2020 - 2035. [Abstract] [Full Text] [PDF]

				J. Wirth, F. Chopin, V. Santoni, G. Viennois, P. Tillard, A. Krapp, L. Lejay, F. Daniel-Vedele, and A. Gojon Regulation of Root Nitrate Uptake at the NRT2.1 Protein Level in Arabidopsis thaliana J. Biol. Chem., August 10, 2007; 282(32): 23541 - 23552. [Abstract] [Full Text] [PDF]

				A. J. Miller, X. Fan, M. Orsel, S. J. Smith, and D. M. Wells Nitrate transport and signalling J. Exp. Bot., July 1, 2007; 58(9): 2297 - 2306. [Abstract] [Full Text] [PDF]

				E. Fernandez and A. Galvan Inorganic nitrogen assimilation in Chlamydomonas J. Exp. Bot., July 1, 2007; 58(9): 2279 - 2287. [Abstract] [Full Text] [PDF]

				F. Chopin, M. Orsel, M.-F. Dorbe, F. Chardon, H.-N. Truong, A. J. Miller, A. Krapp, and F. Daniel-Vedele The Arabidopsis ATNRT2.7 Nitrate Transporter Controls Nitrate Content in Seeds PLANT CELL, May 1, 2007; 19(5): 1590 - 1602. [Abstract] [Full Text] [PDF]