title: Multiple mechanisms of nitrate sensing by Arabidopsis nitrate transceptor NRT1.1.
abstract: In Arabidopsis the plasma membrane nitrate transceptor (transporter/receptor) NRT1.1 governs many physiological and developmental responses to nitrate. Alongside facilitating nitrate uptake, NRT1.1 regulates the expression levels of many nitrate assimilation pathway genes, modulates root system architecture, relieves seed dormancy and protects plants from ammonium toxicity. Here, we assess the functional and phenotypic consequences of point mutations in two key residues of NRT1.1 (P492 and T101). We show that the point mutations differentially affect several of the NRT1.1-dependent responses to nitrate, namely the repression of lateral root development at low nitrate concentrations, and the short-term upregulation of the nitrate-uptake gene NRT2.1, and its longer-term downregulation, at high nitrate concentrations. We also show that these mutations have differential effects on genome-wide gene expression. Our findings indicate that NRT1.1 activates four separate signalling mechanisms, which have independent structural bases in the protein. In particular, we present evidence to suggest that the phosphorylated and non-phosphorylated forms of NRT1.1 at T101 have distinct signalling functions, and that the nitrate-dependent regulation of root development depends on the phosphorylated form. Our findings add to the evidence that NRT1.1 is able to trigger independent signalling pathways in Arabidopsis in response to different environmental conditions.
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: E
authors.initials: E
authors.lastname: Bouguyon
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: F
authors.initials: F
authors.lastname: Brun
authors.affiliation: Amélioration Génétique et Adaptation des Plantes, CIRAD/INRA/SupAgro-M, Montpellier, France.
authors.forename: D
authors.initials: D
authors.lastname: Meynard
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, v.v.i., Rozvojová 263, Prague 6 - Lysolaje 16502, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Kubeš
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: M
authors.initials: M
authors.lastname: Pervent
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: S
authors.initials: S
authors.lastname: Leran
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: B
authors.initials: B
authors.lastname: Lacombe
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: G
authors.initials: G
authors.lastname: Krouk
authors.affiliation: Amélioration Génétique et Adaptation des Plantes, CIRAD/INRA/SupAgro-M, Montpellier, France.
authors.forename: E
authors.initials: E
authors.lastname: Guiderdoni
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, v.v.i., Rozvojová 263, Prague 6 - Lysolaje 16502, Czech Republic.
authors.forename: E
authors.initials: E
authors.lastname: Zažímalová
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, v.v.i., Rozvojová 263, Prague 6 - Lysolaje 16502, Czech Republic.
authors.forename: K
authors.initials: K
authors.lastname: Hoyerová
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: P
authors.initials: P
authors.lastname: Nacry
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, CNRS/INRA/SupAgro-M/UM, Montpellier 34060, France.
authors.forename: A
authors.initials: A
authors.lastname: Gojon