title: Auxin-mediated nitrate signalling by NRT1.1 participates in the adaptive response of Arabidopsis root architecture to the spatial heterogeneity of nitrate availability.
abstract: To optimize their nitrogen nutrition, plants are able to direct root growth in nitrate-rich patches. This depends in Arabidopsis on the NRT1.1 nitrate transporter/sensor. NRT1.1 was shown to display on homogenous medium, an auxin transport activity that lowers auxin accumulation in lateral roots and inhibits their growth at low nitrate. Using a split-root system, we explored the hypothesis that preferential lateral root growth in the nitrate-rich side involves the NRT1.1-dependent repression of lateral root growth in the low nitrate side. Data show that NRT1.1 acts locally to modulate both auxin levels and meristematic activity in response to the low nitrate concentration directly experienced by lateral roots leading to a repression of their growth. A stimulatory role of NRT1.1 in the high nitrate side, which does not rely on changes in auxin levels, is also observed. Altogether, our data suggest that NRT1.1 allows preferential root colonization of nitrate-rich patches by both preventing root growth in response to low nitrate, through modulation of auxin traffic, and stimulating root growth in response to high nitrate, through a yet uncharacterized mechanism. In addition, transcriptional regulation of NRT1.1 affects both mechanisms allowing plants to modulate the effect of nitrate on root branching.
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, UMR 5004 CNRS/INRA/SupAgro-M/UM2, Institut de Biologie Intégrative des Plantes, Place Viala, 34060, Montpellier Cedex 1, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Mounier
authors.forename: Marjorie
authors.initials: M
authors.lastname: Pervent
authors.forename: Karin
authors.initials: K
authors.lastname: Ljung
authors.forename: Alain
authors.initials: A
authors.lastname: Gojon
authors.forename: Philippe
authors.initials: P
authors.lastname: Nacry
mesh_terms: D000222:Adaptation, Physiological; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D006863:Hydrogen-Ion Concentration; D007210:Indoleacetic Acids / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D009566:Nitrates / Q000032:analysis / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D030821:Plants, Genetically Modified; D015398:Signal Transduction
chemical_list: D027321:Anion Transport Proteins; D007210:Indoleacetic Acids; C101492:NRT1.1 protein, Arabidopsis; D009566:Nitrates; D010937:Plant Growth Regulators; D010940:Plant Proteins
keywords: Arabidopsis thaliana; lateral roots; split root