Abstract
Arabidopsis DREB2A is an important stress-responsible transcription factor that induces drastic phase change of plant to adapt environmental stresses. To avoid adverse effects of this emergency phase, expression of DREB2A is tightly regulated at both transcriptional and post-translational levels. To elucidate the transcriptional regulation mechanism of DREB2A under dehydration stress, a series of truncate fragments of the DREB2A promoter were prepared and tested their transcriptional activity individually. We found that an ABRE sequence located around -100 b from the transcriptional initiation site is responsible for dehydration-induced transcript accumulation. The AREB1, AREB2, and ABF3 transcription factors could bind to and activate the DREB2A promoter in an ABRE-dependent manner. We also confirmed that the transcriptional activity of a 1.8 kb DREB2A promoter fragment under dehydration stress was depressed in an areb1 areb2 abf3 triple mutant background compared with that in the wild type. Furthermore, genetic disturbance of ABA signal cascade or ABA biosynthesis resulted in alleviated transcriptional accumulation of DREB2A against dehydration stress.
