Heterologous Expression of the Apple MdbZIP26 Gene in Arabidopsis thaliana Improves Resistance to High Salinity and Drought Stress

Abstract

High salinity and drought seriously limit the production of many crops worldwide, including apple (Malus x. domestica Borkh). Members of the bZIP family of transcription factors play important roles in abiotic stress in various plants, but there have been few studies in perennial tree species. In our previous study, we conducted a genome-wide survey of bZIP family transcription factor genes in apple. Here, we focused on one of these genes, MdbZIP26, which is induced by high salinity, drought, and exogenous abscisic acid (ABA). The MdbZIP26 promoter contains several apparent cis-acting elements associated with abiotic stress response, such as ABRE/G-box, DRE, GT1, and GMSCAM4. The temporal and spatial expression patterns of MdbZIP26 were consistent with a role in abiotic stress response. Arabidopsis thaliana plants expressing MdbZIP26 showed enhanced tolerance to dehydration and salinity, and this was associated with altered expression of ABA/stress-regulated genes. Considered together, these results suggest that MdbZIP26 plays a role in the resistance of drought and high salinity stress in apple via ABA-mediated signaling.