Abstract
A cis-acting element DRE is involved in dehydration, high-salt and low-temperature induced gene expression. We have been isolated Arabidopsis cDNAs encoding DRE-binding proteins, DREB1/CBF and DREB2. DREB1 and DREB2 function as transcriptional activators in cold- and drought-responsive gene expression, respectively. Overexpression of DREB1A in transgenic Arabidopsis activated expression of many stress-inducible genes and resulted in improved tolerance to drought and freezing. We searched for downstream genes of DREB1A using microarray analysis and identified more than 40 downstream genes of DREB1A. We also carried out metabolome analysis to examine the changes of metabolites that occur in the transgenic plants. On the other hand, we overexpressed a constitutive active form of DREB2A in Arabidopsis. The DREB2A transgenic plants showed strong tolerance to drought but not so strong to cold stress. We analyzed downstream genes of DREB2A using microarray and found that some downstream genes of DREB2A are different from those of DREB1A.
