Functional Analysis of a bZIP Transcription Factor in Arabidopsis thaliana by Using CRES-T Method: Role of AREB1 in ABRE-dependent ABA Signaling That Enhances Drought Stress Tolerance.

Abstract

The bZIP transcription factors are proteins that contain a basic region mediating sequence-specific DNA-binding followed by a leucine zipper region required for dimeraization. The Arabidopsis genome sequence contains approximately 80 distinct members of the bZIP family. The bZIP transcription factors regulate crucial processes including seed maturation, stress signaling, and flower development. AREB1 is a bZIP transcription factor that binds ABRE in the promoter region of ABA-inducible genes. In this study, to minimize the effects of phenotypic masking due to functional redundancy, we used CRES-T in loss-of-function analysis of AREB1. In addition to a gain-of-function mutant, we assessed two types of loss-of-function mutants in growth phenotypes, gene expression, ABA sensitivity, and drought tolerance: a T-DNA insertion mutant of AREB1, areb1, and transgenic plants overexpressing AREB1 fused to the SRDX repression domain. We will discuss the role of AREB1 in ABRE-dependent ABA signaling that enhances drought stress tolerance.