The Arabidopsis NRT1.1 transporter participates in the signaling pathway triggering root colonization of nitrate-rich patches.
Localized proliferation of lateral roots in NO(3)(-)-rich patches is a striking example of the nutrient-induced plasticity of root development. In Arabidopsis, NO(3)(-) stimulation of lateral root elongation is apparently under the control of a NO(3)(-)-signaling pathway involving the ANR1 transcription factor. ANR1 is thought to transduce the NO(3)(-) signal internally, but the upstream NO(3)(-) sensing system is unknown. Here, we show that mutants of the NRT1.1 nitrate transporter display a strongly decreased root colonization of NO(3)(-)-rich patches, resulting from reduced lateral root elongation. This phenotype is not due to lower specific NO(3)(-) uptake activity in the mutants and is not suppressed when the NO(3)(-)-rich patch is supplemented with an alternative N source but is associated with dramatically decreased ANR1 expression. These results show that NRT1.1 promotes localized root proliferation independently of any nutritional effect and indicate a role in the ANR1-dependent NO(3)(-) signaling pathway, either as a NO(3)(-) sensor or as a facilitator of NO(3)(-) influx into NO(3)(-)-sensing cells. Consistent with this model, the NRT1.1 and ANR1 promoters both directed reporter gene expression in root primordia and root tips. The inability of NRT1.1-deficient mutants to promote increased lateral root proliferation in the NO(3)(-)-rich zone impairs the efficient acquisition of NO(3)(-) and leads to slower plant growth. We conclude that NRT1.1, which is localized at the forefront of soil exploration by the roots, is a key component of the NO(3)(-)-sensing system that enables the plant to detect and exploit NO(3)(-)-rich soil patches.
Remans
Tony
T
Biochimie et Physiologie Moléculaire des Plantes, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, UM2, et AgroM, Place Viala, F-34060 Montpellier, France.
Nacry
Philippe
P
Pervent
Marjorie
M
Filleur
Sophie
S
Diatloff
Eugene
E
Mounier
Emmanuelle
E
Tillard
Pascal
P
Forde
Brian G
BG
Gojon
Alain
A
D027321:Anion Transport Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D009154:Mutation / Q000235:genetics; D009566:Nitrates / Q000494:pharmacology*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
C109964:ANR1 protein, Arabidopsis; D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; C101492:NRT1.1 protein, Arabidopsis; D009566:Nitrates; D010940:Plant Proteins; D014157:Transcription Factors