期刊
PLANT CELL AND ENVIRONMENT
卷 30, 期 11, 页码 1366-1380出版社
WILEY
DOI: 10.1111/j.1365-3040.2007.01712.x
关键词
nitrate transport; whole plant N signalling
The Arabidopsis thaliana AtNRT2.1 gene, which encodes a NO3- transporter involved in high-affinity uptake by the roots, is a molecular target of several mechanisms responsible for the regulation of root NO3- 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 NO3-, 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 NO3- 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 NO3- 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.
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