Eggplant AP2/ERF Transcription Factor SmWIN1 Promotes Wax Biosynthesis by Activating the Expression of SmKCS6 and...

Epicuticular wax not only determines the glossiness of eggplant fruit skin but also plays a crucial role in moisture retention, extending shelf life, and enhancing plant resistance to both biotic and abiotic stresses. However, the key regulatory genes and molecular mechanisms involved in wax biosynthesis in eggplants remain largely unclear. This study reports the identification of a positive regulatory factor for wax biosynthesis in eggplants, the AP2/ERF transcription factor SmWIN1 (WAX INDUCER1). SmWIN1 exhibits transcriptional activation activity and is primarily expressed in the fruit peel, with its expression being suppressed by UV-B treatment while induced by 4°C, PEG, and NaCl treatments. Overexpression of SmWIN1 significantly promotes wax biosynthesis in both the leaves and fruit peels of eggplants, enhancing their glossiness. Transcriptomic sequencing analysis revealed that over 20 structural genes involved in wax biosynthesis, including SmKCS6 (3-Ketoacyl-CoA Synthase 6) and SmLACS2 (Long-Chain Acyl-CoA Synthetase 2), were upregulated in the leaves of SmWIN1 transgenic plants. Furthermore, yeast one-hybrid and dual-luciferase assays demonstrated that SmWIN1 activates the expression of these genes by binding to their respective promoters. This study elucidates the key regulatory genes and molecular mechanisms underlying epicuticular wax biosynthesis in eggplants, thereby deepening our understanding of the molecular regulation of wax formation in plants.