A NOVEL CIS-ACTING ELEMENT IN AN ARABIDOPSIS GENE IS INVOLVED IN RESPONSIVENESS TO DROUGHT, LOW-TEMPERATURE, OR HIGH-SALT STRESS

Two genes, rd29A and rd29B, which are closely located on the Arabidops is genome, are differentially induced under conditions of dehydration, low temperature, high salt, or treatment with exogenous abscisic acid (ABA). It appears that rd29A has at least two cis-acting elements, on e involved in the ABA-associated response to dehydration and the other induced by changes in osmotic potential, and that rd29B contains at l east one cis-acting element that is involved in ABA-responsive, slow i nduction. We analyzed the rd29A promoter in both transgenic Arabidopsi s and tobacco and identified a novel cis-acting, dehydration-responsiv e element (DRE) containing 9 bp, TACCGACAT, that is involved in the fi rst rapid response of rd29A to conditions of dehydration or high salt. DRE is also involved in the induction by low temperature but does not function in the ABA-responsive, slow expression of rd29A. Nuclear pro teins that specifically bind to DRE were detected in Arabidopsis plant s under either high-salt or normal conditions. Different cis-acting el ements seem to function in the two-step induction of rd29A and in the slow induction of rd29B under conditions of dehydration, high salt, or low temperature.