Identification of a 150 bp cis-acting element of the AtNRT2.1 promoter involved in the regulation of gene expression by the N and C status of the plant.
The Arabidopsis thaliana AtNRT2.1 gene, which encodes a NO(3)(-) transporter involved in high-affinity uptake by the roots, is a molecular target of several mechanisms responsible for the regulation of root NO(3)(-) acquisition by the N status of the plant. All levels of AtNRT2.1 expression (promoter activity, transcript level, protein accumulation, transport activity) are coordinately up-regulated in the presence of NO(3)(-), and repressed by downstream N metabolites. Transgenic plants expressing the GUS reporter gene under the control of upstream sequences of AtNRT2.1 have been studied to identify elements targeted by these two regulatory mechanisms. A 150 bp sequence located upstream of the TATA box that is required for both stimulation by NO(3)(-) and repression by N metabolites of the promoter has been identified. This sequence is able to confer these two regulations to a minimal promoter. Split-root experiments indicate that the stimulation of the chimaeric promoter by NO(3)(-) occurs only at the local level, whereas its repression by N metabolites is mediated by a systemic signal spread to the whole plant. The activity of the cis-acting 150 bp element is also regulated by sucrose supply to the roots, suggesting a possible interaction between N and C signalling within this short region. Accordingly, multiple motifs potentially involved in regulations by N and/or C status are identified within this sequence by bioinformatic approaches. This is the first report of such a cis-acting element in higher plants.
Girin
Thomas
T
UMR 5004, Institut National de la Recherché Agronomique (INRA)--Centre National de la Recherche Scientifique (CNRS)-Sup Agro-UM2, Institut de Biologie Intégrative des Plantes, 2 Place Viala, Montpellier, F-34060 France.
Lejay
Laurence
L
Wirth
Judith
J
Widiez
Thomas
T
Palenchar
Peter M
PM
Nazoa
Patricia
P
Touraine
Bruno
B
Gojon
Alain
A
Lepetit
Marc
M
D027321:Anion Transport Proteins / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics*; D002241:Carbohydrates; D002244:Carbon / Q000378:metabolism*; D019295:Computational Biology; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D009584:Nitrogen / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014158:Transcription, Genetic
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; D002241:Carbohydrates; D002244:Carbon; D009584:Nitrogen; C477335:NRT2.1 protein, Arabidopsis