Reference "Metabolic regulation of asparagine synthetase gene expression in maize (Zea mays L.) root tips"

Reference ID

7108

Title

Metabolic regulation of asparagine synthetase gene expression in maize (Zea mays L.) root tips

Source

The Plant journal : for cell and molecular biology, 1996, vol. 9, pp. 1-11

Authors (4)

Chevalier-C	Bourgeois-E
Just-D	Raymond-P

Abstract

Differential hybridization of a cDNA library constructed with poly(A)+ mRNA from
24 h starved maize (Zea mays L.) root tips, resulted in the isolation of a cDNA
(called pZSS1) that was highly induced during glucose deprivation. The
nucleotide sequence analysis of the full-length cDNA allowed its identification
by comparison with sequence data bases. The 586 amino acid sequence encoded by
pZSS1 was shown to be about 60% identical to sequences of asparagine synthetases
(EC 6.3.5.4) from Asparagus officinalis, Pisum sativum, Arabidopsis thaliana and
Brassica oleracea. Southern blot analysis of maize genomic DNA showed that
asparagine synthetase may be encoded by at least two genes. The use of a
specific probe for the 3' untranslated region of pZSS1 in Northern blot
experiments, revealed that the isolated AS gene was essentially expressed in
roots of maize seedlings. Time course analysis revealed that maximal expression
of the gene corresponding to pZSS1 occurs between 18 and 24 h after the onset of
the starvation treatment. The steady-state levels of transcripts in maize root
tips were found to change under various incubation conditions. Exogenous supply
of metabolizable sugars downregulated the gene expression, while carbohydrate
deprivation or feeding with non-metabolizable sugars resulted in the induction
of gene expression. In addition to carbohydrate deprivation, the effects of
nitrogen metabolite supply and stress conditions indicate that gene expression
might be under metabolic control in maize root tips. The intracellular nitrogen
to carbon ratio might be an important factor for the regulation of asparagine
synthetase gene expression.