An apple AP2/EREBP-type transcription factor, MdWRI4, enhances plant resistance to abiotic stress by increasing cuticular wax load

Apple cuticular waxes have important functions in responses to mechanical injury, pathogen invasion, low temperatures, drought, salinity, and other stresses. In recent years, AP2/EREBP-type transcription factors have been shown to play an important role in cuticular wax biosynthesis. However, it remains unclear whether the apple AP2/EREBP-type transcription factor WRI4 has a similar function, and the molecular mechanisms of its regulation have not been characterized. In this study, we identified an AP2/EREBP-type transcription factor, MdWRI4, from apple and demonstrated that it was localized in the nucleus. The MdWRI4 gene was highly expressed in the pericarp, and heterologous expression of MdWRI4 in Arabidopsis caused increased cuticular wax biosynthesis in stems and leaves. MdWRI4 transgenic Arabidopsis exhibited reduced epidermal permeability, water loss, and chlorophyll leaching rate, as well as improved drought and salt resistance. Finally, we predicted the protein interaction network of the MdWRI4 protein in order to clarify potential pathways by which MdWRI4 regulates the response to environmental stress.