Nitrate-Regulated Auxin Transport by NRT1.1 Defines a Mechanism for Nutrient Sensing in Plants

• Published in: Developmental cell 2010-06, Vol.18 (6), p.927-937
• Main Authors: Krouk, Gabriel, Lacombe, Benoît, Bielach, Agnieszka, Perrine-Walker, Francine, Malinska, Katerina, Mounier, Emmanuelle, Hoyerova, Klara, Tillard, Pascal, Leon, Sarah, Ljung, Karin, Zazimalova, Eva, Benkova, Eva, Nacry, Philippe, Gojon, Alain
• Format: Article
• Language: English
• Subjects: Animals; Arabidopsis - growth & development; Arabidopsis - metabolism; Biological and medical sciences; Biological Transport, Active - physiology; Cell differentiation, maturation, development, hematopoiesis; Cell physiology; Cells, Cultured; Chemoreceptor Cells - metabolism; DEVBIO; Female; Food; Forest Science; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - physiology; Indoleacetic Acids - metabolism; Life Sciences; Molecular and cellular biology; Mutation - genetics; Nitrates - metabolism; Oocytes; Periplasmic Binding Proteins - genetics; Periplasmic Binding Proteins - metabolism; Plant Roots - growth & development; Plant Roots - metabolism; PROTEINS; Signal Transduction - physiology; SIGNALING; Skogsvetenskap; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; Vegetal Biology; Xenopus
• ISSN: 1534-5807; 1878-1551; 1878-1551
• DOI: 10.1016/j.devcel.2010.05.008

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. ► The NRT1.1 nitrate (NO 3 − ) transporter/sensor acts as an auxin influx facilitator ► NO 3 − sensing by NRT1.1 involves inhibition of its auxin transport activity by NO 3 − ► NRT1.1 modulates auxin gradients in lateral root primordia in response to NO 3 − ► NRT1.1 represses lateral root growth at low external NO 3 − concentration