Abstract
Under abiotic stress conditions such as drought and high salinity, ABA levels increase in plants, and ABA regulates the expression of many genes that function in the stress tolerance. In the promoters of such ABA-regulated genes, a conserved cis-element designated ABRE (ABA-responsive element), which controls ABA-responsive gene expression, has been identified. Arabidopsis cDNAs encoding bZIP-type transcription factors referred as ABRE-binding (AREB) proteins were isolated using the yeast one-hybrid screening method. Among these transcription factors, expression of AREB1, AREB2, and ABF3 was upregulated by ABA, dehydration, and high-salinity stresses in Arabidopsis plants. Based on results of analyses of both gain- and loss-of function mutants of AREB1, AREB2, and ABF3, here we report that these AREB family transcription factors are involved in the ABA/stress signaling. Moreover, taken together with the information on downstream target genes obtained by microarray analyses, we will discuss the role of each AREB transcription factor.
