| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
|
First published online September 29, 2006; 10.1104/pp.106.085209 Plant Physiology 142:1304-1317 (2006) © 2006 American Society of Plant Biologists Characterization of a Two-Component High-Affinity Nitrate Uptake System in Arabidopsis. Physiology and Protein-Protein Interaction1,[W]Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom (M.O., S.J.S., A.J.M.); and Unité de la Nutrition Azotée des Plantes, Institut National de la Recherche Agronomique, F–78026 Versailles cedex, France (F.C., O.L., A.K., F.D.-V.)
The identification of a family of NAR2-type genes in higher plants showed that there was a homolog in Arabidopsis (Arabidopsis thaliana), AtNAR2.1. These genes encode part of a two-component nitrate high-affinity transport system (HATS). As the Arabidopsis NRT2 gene family of nitrate transporters has been characterized, we tested the idea that AtNAR2.1 and AtNRT2.1 are partners in a two-component HATS. Results using the yeast split-ubiquitin system and Xenopus oocyte expression showed that the two proteins interacted to give a functional HATS. The growth and nitrogen (N) physiology of two Arabidopsis gene knockout mutants, atnrt2.1-1 and atnar2.1-1, one for each partner protein, were compared. Both types of plants had lost HATS activity at 0.2 mM nitrate, but the effect was more severe in atnar2.1-1 plants. The relationship between plant N status and nitrate transporter expression revealed a pattern that was characteristic of N deficiency that was again stronger in atnar2.1-1. Plants resulting from a cross between both mutants (atnrt2.1-1 x atnar2.1-1) showed a phenotype like that of the atnar2.1-1 mutant when grown in 0.5 mM nitrate. Lateral root assays also revealed growth differences between the two mutants, confirming that atnar2.1-1 had a stronger phenotype. To show that the impaired HATS did not result from the decreased expression of AtNRT2.1, we tested if constitutive root expression of a tobacco (Nicotiana plumbaginifolia) gene, NpNRT2.1, previously been shown to complement atnrt2.1-1, can restore HATS to the atnar2.1-1 mutant. These plants did not recover wild-type nitrate HATS. Taken together, these results show that AtNAR2.1 is essential for HATS of nitrate in Arabidopsis.
1 This work was supported by the European Union (grants no. BIO4CT972231, Research Training Network "Plant use of nitrate" HPRN–CT–2002–00247, and Gabi-Génoplante joint project AF2001/092). Rothamsted Research is grant aided by the Biotechnology and Biological Sciences Research Council of the United Kingdom. 2 Present address: Ameloriation des Plantes et Biotechnolgies Vegetales, UMR 118, INRA-Agrocampus Rennes, BP 35327, 35653 Le Rheu cedex, France. 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 J. Miller (tony.miller@bbsrc.ac.uk). [W] The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.106.085209 * Corresponding author; e-mail tony.miller{at}bbsrc.ac.uk; fax 44–1582–763010. Received June 16, 2006; accepted September 19, 2006; published September 29, 2006. This article has been cited by other articles:
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY | THE PLANT CELL | |
|---|---|---|---|
