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Article Addendum
Nitrate Signaling and the Two Component High Affinity Uptake System in Arabidopsis
Mathilde Orsel, Franck Chopin, Olivier Leleu, Susan J. Smith, Anne Krapp, Francoise Daniel-Vedele and Anthony J. Miller
volume 2 | issue 4
july/august 2007Pages: 260 - 262
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Nitrate transporters are important for nitrogen acquisition by plants and in algae some require two gene products, NRT2 and NAR2, for function. The NRT2 family was already described and the recent identification of a family of the NAR2-type genes in higher plants showed that there was a homologue in Arabidopsis, AtNAR2.1. Using heterologous expression system in yeast and oocytes we showed that the two Arabidopsis AtNRT2.1 and AtNAR2.1 proteins interacted to give a functional high affinity nitrate transport system (HATS). The gene knock out mutant atnar2.1-1 is deficient specifically for HATS activity and the resulting growth phenotype on low nitrate concentration is more severe than for the atnrt2.1-1 knock out mutant. Physiological characterisation of the plant N status and gene expression revealed a pattern that was characteristic of severe nitrogen deficiency. Consistent with the down regulation of AtNRT2.1 expression, the atnar2.1-1 plants also displayed the same phenotype as atnrt2.1 mutants in lateral root (LR) response to low nitrate supply. Using atnar2.1-1 plants constitutively expressing the NpNRT2.1 gene, we now show a specific role for AtNAR2.1 in LR response to low nitrate supply. AtNAR2.1 is also involved in the repression of LR initiation in response to high ratios of sucrose to nitrogen in the medium. Therefore the two component system itself is likely to be involved in the signaling pathway integrating nutritional cues for LR architecture regulation. Using a green fluorescent protein-NRT2.1 protein fusion we show the essential role of AtNAR2.1 for the presence of AtNRT2.1 to the plasma membrane.
Authors
Mathilde Orsel
University Rennes, Rennes France
Franck Chopin
Institut National de la Recherche Agronomique, Versailles, France
Olivier Leleu
Institut National de la Recherche Agronomique, Versailles, France
Susan J. Smith
Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
Anne Krapp
Institut National de la Recherche Agronomique, Versailles, France
Francoise Daniel-Vedele
Institut National de la Recherche Agronomique, Versailles, France
Anthony J. Miller
Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDF If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.