Abstract
The transcription factors in the ABA Response Element Binding (AREB) protein family were differentially regulated under multiple stress conditions; however, functional analyses of AREB in Populus euphratica Oliv. had not been conducted previously. In the present study, the comprehensive identification of the P. euphratica AREB gene family and the function of PeAREB04 in response to drought stress in P. euphratica were elucidated. A comprehensive analysis of the PeAREB family was first performed, followed by the determination of their expression patterns under drought stress. Bioinformatics analysis revealed that thirteen AREB genes were identified across the P. euphratica genome, with these genes distributed across eight chromosomes in a seemingly random pattern. Phylogenetic analysis indicated that the PeAREB genes could be categorized into four distinct branches. Cis-acting element analysis revealed that most PeAREB genes contained multiple hormone- and stress-responsive elements. Transcriptomic sequencing of P. euphratica seedlings under drought stress showed that most PeAREB genes responded rapidly to drought stress in either the leaves or roots. One gene, PeAREB04, was selected for further functional validation due to its significant upregulation in both leaves and roots under drought stress. Overexpression of PeAREB04 in Arabidopsis thaliana resulted in a high survival rate, reduced water loss in isolated leaves, and a significant reduction in stomatal aperture under natural drought conditions. Drought stress simulations using mannitol further demonstrated that overexpression of PeAREB04 significantly enhanced root elongation. These findings indicate that the identification of the PeAREB gene family and the characterization of PeAREB04's role in drought stress have been largely accomplished. Furthermore, the PeAREB04 gene demonstrates considerable potential as a key target for future genetic engineering strategies aimed at enhancing plant drought resistance.