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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

2007; Wiley; Volume: 30; Issue: 11 Linguagem: Inglês

10.1111/j.1365-3040.2007.01712.x

1365-3040

Thomas Girin, Laurence Lejay, Judith Wirth, Thomas Widiez, Peter M. Palenchar, Patricia Nazoa, Bruno Touraine, Alaín Gojon, Marc Lepetit,

Photosynthetic Processes and Mechanisms

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.