Comprehensive Identification of AREB Gene Family in Populus euphratica Oliv. and Functional Analysis of PeAREB04 in Drought Tolerance

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 <i>Populus euphratica</i> Oliv. had not been conducted previously. In the present study, the comprehensive identification of the <i>P. euphratica AREB</i> gene family and the function of <i>PeAREB04</i> in response to drought stress in <i>P. euphratica</i> were elucidated. A comprehensive analysis of the <i>PeAREB</i> family was first performed, followed by the determination of their expression patterns under drought stress. Bioinformatics analysis revealed that thirteen <i>AREB</i> genes were identified across the <i>P. euphratica</i> genome, with these genes distributed across eight chromosomes in a seemingly random pattern. Phylogenetic analysis indicated that the <i>PeAREB</i> genes could be categorized into four distinct branches. Cis-acting element analysis revealed that most <i>PeAREB</i> genes contained multiple hormone- and stress-responsive elements. Transcriptomic sequencing of <i>P. euphratica</i> seedlings under drought stress showed that most <i>PeAREB</i> genes responded rapidly to drought stress in either the leaves or roots. One gene, <i>PeAREB04</i>, was selected for further functional validation due to its significant upregulation in both leaves and roots under drought stress. Overexpression of <i>PeAREB04</i> in <i>Arabidopsis thaliana</i> 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 <i>PeAREB04</i> significantly enhanced root elongation. These findings indicate that the identification of the <i>PeAREB</i> gene family and the characterization of <i>PeAREB04</i>'s role in drought stress have been largely accomplished. Furthermore, the <i>PeAREB04</i> gene demonstrates considerable potential as a key target for future genetic engineering strategies aimed at enhancing plant drought resistance.