Abstract
Overexpression of DREB1A in transgenic plants activated the expression of many stress-inducible genes and resulted in not only improved tolerance to drought, high salt and freezing but also growth retardation. To identify downstream genes of DREB1A, we performed 22k oligarray analysis. The identified genes were classified into direct target genes of DREB1A and the others based on their expression patterns in response to cold stress. We also searched for conserved sequences in the promoter regions of the direct target genes and found A/GCCGACNT in their promoter regions from –51 to -450 as a consensus DRE. The recombinant DREB1A protein bound to A/GCCGACNT more efficiently than to A/GCCGACNA/G/C. The downstream genes also included genes for transcriptional regulation in response to stress. One of regulatory genes, STZ encodes a transcriptional repressor and may be involved in the mechanism of growth retardation in transgenic plants.
