In higher plants, a cis-acting element, DRE/CRT, is involved in gene expression responsive to drought and low-temperature stress. To understand signal transduction pathways from the cold stress signal to gene expression, we characterized a gene family for DRE/CRT-binding proteins DREB1A and CBF1 in Arabidopsis thaliana. DREB1A and CBF1 were shown to be involved in low-temperature-responsive gene expression. We screened an Arabidopsis genomic DNA library with the cDNA fragment of DREB1A as a probe and isolated DREB1A and 2 related genes, DREB1B (= CBF1) and DREB1C. These were arrayed in the order B, A, C in an 8.7 kb region of Arabidopsis chromosome 4. Northern blot analysis using gene-specific probes showed that the 3 DREB1 genes are induced mainly by cold stress but not by osmotic stress in leaves, roots, and stems. Several conserved sequences were found in the promoter regions of all 3 genes. The beta-glucuronidase (GUS) reporter gene driven by the DREB1 promoters was induced at transcriptional level by low temperature in transgenic Arabidopsis plants.
Copyright 1998 Academic Press.