This study showed that AP2/EREBP transcription factor MdSHINE2 functioned in mediating cuticular permeability, sensitivity to abscisic acid (ABA), and drought resistance by regulating wax biosynthesis. Plant cuticular wax plays crucial roles in protecting plants from environmental stresses, particularly drought stress. Many enzymes and transcription factors involved in wax biosynthesis have been identified in plant species. In this study, we identified an AP2/EREBP transcription factor, MdSHINE2 from apple, which is a homolog of AtSHINE2 in Arabidopsis. MdSHINE2 was constitutively expressed at different levels in various apple tissues, and the transcription level of MdSHINE2 was induced substantially by abiotic stress and hormone treatments. MdSHINE2-overexpressing Arabidopsis exhibited great change in cuticular wax crystal numbers and morphology and wax composition of leaves and stems. Moreover, MdSHINE2 heavily influenced cuticular permeability, sensitivity to abscisic acid, and drought resistance.
Keywords: ABA sensitivity; AP2/EREBP; Apple; Crystal morphology; Cuticular permeability; Drought resistance; Wax load.