Transcriptome reveals insights into the regulatory mechanism of cuticular wax synthesis in developing apple fruit

Cuticular wax is essential for ensuring the quality and safety of postharvest fruit. Although the ultrastructure and composition of fruit wax have been elucidated, the molecular mechanisms of wax synthesis remain unknown. The study suggested that the cuticular wax accumulation was continuous throughout in apple fruit (Malus domestica Borkh. cv. Red Fuji) development. Scanning electron microscopy analysis revealed an increase in wax plate crystals and variation in wax structures during this process. Further transcriptome analysis revealed that the cuticular wax biosynthesis involves lipid metabolisms, including fatty acid biosynthesis, fatty acid degradation, etc. The transcription factor families, such as MYBs, ERFs, WRKYs, NACs, and HB-other, were crucial in the transcriptional regulation of DEGs involved in lipid metabolism. Additionally, the tricarboxylic acid cycle and sugar metabolism were important in cuticular wax biosynthesis. Overall, these findings have significant implications to improve fruit quality by providing insight into the molecular mechanisms of cuticular wax biosynthesis.