Abstract
Under abiotic stress conditions such as drought and high salinity, abscisic acid (ABA) is accumulated in plant cells and induces many genes that function in the stress tolerance. In the promoter regions of such ABA-inducible genes, the cis-elements, ABRE (ABA-responsive element), are conserved. AREB/ABF proteins were isolated as ABRE-binding proteins by using yeast one-hybrid method. Among nine AREB/ABF genes in Arabidopsis, AREB1, AREB2, and ABF3 are induced by dehydration, NaCl, and ABA treatments in vegetative tissues. We have demonstrated that AREB1, AREB2, and ABF3 are master transcription factors that regulate ABRE-dependent ABA signaling involved in drought stress tolerance by using the areb1 areb2 abf3 triple mutant. In addition to the three AREB/ABFs, ABF1 is also in the same clade in the phylogenetic tree. Here, we will report a role of ABF1 in ABA signaling based on the results of the comparative analyses using the areb1 areb2 abf3 abf1 quadruple mutant and the areb1 areb2 abf3 triple mutant.
