Nitrate-regulated auxin transport by NRT1.1 defines a mechanism for nutrient sensing in plants.
Nitrate is both a nitrogen source for higher plants and a signal molecule regulating their development. In Arabidopsis, the NRT1.1 nitrate transporter is crucial for nitrate signaling governing root growth, and has been proposed to act as a nitrate sensor. However, the sensing mechanism is unknown. Herein we show that NRT1.1 not only transports nitrate but also facilitates uptake of the phytohormone auxin. Moreover, nitrate inhibits NRT1.1-dependent auxin uptake, suggesting that transduction of nitrate signal by NRT1.1 is associated with a modification of auxin transport. Among other effects, auxin stimulates lateral root development. Mutation of NRT1.1 enhances both auxin accumulation in lateral roots and growth of these roots at low, but not high, nitrate concentration. Thus, we propose that NRT1.1 represses lateral root growth at low nitrate availability by promoting basipetal auxin transport out of these roots. This defines a mechanism connecting nutrient and hormone signaling during organ development.
Krouk
Gabriel
G
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.
Lacombe
Benoît
B
Bielach
Agnieszka
A
Perrine-Walker
Francine
F
Malinska
Katerina
K
Mounier
Emmanuelle
E
Hoyerova
Klara
K
Tillard
Pascal
P
Leon
Sarah
S
Ljung
Karin
K
Zazimalova
Eva
E
Benkova
Eva
E
Nacry
Philippe
P
Gojon
Alain
A
D000818:Animals; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D001693:Biological Transport, Active / Q000502:physiology; D002478:Cells, Cultured; D002628:Chemoreceptor Cells / Q000378:metabolism; D005260:Female; D005502:Food; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009566:Nitrates / Q000378:metabolism*; D009865:Oocytes; D033902:Periplasmic Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus
D007210:Indoleacetic Acids; D009566:Nitrates; D033902:Periplasmic Binding Proteins; D025521:Tumor Suppressor Proteins; C018963:histidine-binding protein