PLANT PHYSIOLOGY , Vol 106, Issue 2 477-484, Copyright © 1994 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
5[prime] Proximal Regions of Arabidopsis Nitrate Reductase Genes Direct Nitrate-Induced Transcription in Transgenic Tobacco
Y. Lin, C. F. Hwang, J. B. Brown and C. L. Cheng
Department of Biological Sciences, The University of Iowa, Iowa City, Iowa 52242
Nitrate reductase (NR) is the first enzyme in nitrate assimilation, a
critical process for plant survival. The regulation of NR gene expression
is complex, involving both internal and external factors. Of these, nitrate
induction of NR gene expression has been studied most extensively and is
well conserved among bacteria, fungi, and higher plants. We are interested
in understanding the mechanism of nitrate induction of higher plant NR
genes. Here we describe promoter analyses of the 5[prime] flanking regions
of the Arabidopsis NR genes, NR1 and NR2, with respect to nitrate induction
of gene expression. To facilitate these analyses, a nitrate induction
procedure using T1 transgenic tobacco plants was established. Approximately
1.5-kb 5[prime] flanking regions of the two Arabidopsis NR genes (NR1 and
NR2) were fused to a reporter gene and its expression in transgenic plants
was analyzed. Deletion analyses of these regions show that 238- and 188-bp
5[prime] flanking regions of the NR1 and NR2, respectively, contain
sequences responsive to nitrate induction.
