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Characterization of the signalling pathways involved in the repression of root nitrate uptake by nitrate in Arabidopsis thaliana.
- Source :
- Journal of Experimental Botany; 8/3/2023, Vol. 74 Issue 14, p4244-4258, 15p
- Publication Year :
- 2023
-
Abstract
- In Arabidopsis thaliana , root high-affinity nitrate (NO<subscript>3</subscript><superscript>–</superscript>) uptake depends mainly on NRT2.1, 2.4, and 2.5, which are repressed by high NO<subscript>3</subscript><superscript>–</superscript> supply at the transcript level. For NRT2.1 , this regulation is due to the action of (i) feedback down-regulation by N metabolites and (ii) repression by NO<subscript>3</subscript><superscript>–</superscript> itself mediated by the transceptor NRT1.1(NPF6.3). However, for NRT2.4 and NRT2.5 , the signalling pathway(s) remain unknown as do the molecular elements involved. Here we show that unlike NRT2.1 , NRT2.4 and NRT2.5 are not induced in an NO<subscript>3</subscript><superscript>–</superscript> reductase mutant but are up-regulated following replacement of NO<subscript>3</subscript><superscript>–</superscript> by ammonium (NH<subscript>4</subscript><superscript>+</superscript>) as the N source. Moreover, increasing the NO<subscript>3</subscript><superscript>–</superscript> concentration in a mixed nutrient solution with constant NH<subscript>4</subscript><superscript>+</superscript> concentration results in a gradual repression of NRT2.4 and NRT2.5 , which is suppressed in an nrt1.1 mutant. This indicates that NRT2.4 and NRT2.5 are subjected to repression by NRT1.1-mediated NO<subscript>3</subscript><superscript>–</superscript> sensing, and not to feedback repression by reduced N metabolites. We further show that key regulators of NRT2 transporters, such as HHO1, HRS1, PP2C, LBD39, BT1, and BT2, are also regulated by NRT1.1-mediated NO<subscript>3</subscript><superscript>–</superscript> sensing, and that several of them are involved in NO<subscript>3</subscript><superscript>–</superscript> repression of NRT2.1 , NRT2.4 , and NRT2.5. Finally, we provide evidence that it is the phosphorylated form of NRT1.1 at the T101 residue, which is most active in triggering the NRT1.1-mediated NO<subscript>3</subscript><superscript>–</superscript> regulation of all these genes. Altogether, these data led us to propose a regulatory model for high-affinity NO<subscript>3</subscript><superscript>–</superscript> uptake in Arabidopsis, highlighting several NO<subscript>3</subscript><superscript>–</superscript> transduction cascades downstream of the phosphorylated form of the NRT1.1 transceptor. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00220957
- Volume :
- 74
- Issue :
- 14
- Database :
- Complementary Index
- Journal :
- Journal of Experimental Botany
- Publication Type :
- Academic Journal
- Accession number :
- 169792690
- Full Text :
- https://doi.org/10.1093/jxb/erad149