Abstract

Fatty acyl-CoA reductases (FARs) catalyze the formation of primary alcohols, which are key components of plant cuticular wax. Although a few FAR members have been functionally characterized in Arabidopsis and several other species, their roles remain largely unexplored in Cucurbitaceae crops. Here, we identified five CsFAR genes in the cucumber genome, unevenly distributed across chromosomes 1, 4, and 6. Phylogenetic and collinearity analyses revealed that CsFARs share conserved evolutionary relationships with FARs from Arabidopsis thaliana , wheat, and other Cucurbitaceae species. Promoter cis-element analysis indicated potential regulation of CsFARs by light, phytohormones, and multiple abiotic stresses. Among the five CsFAR members, CsFAR3-like exhibited the highest expression across tissues and was strongly induced by drought, salt, jasmonic acid, and Podosphaera xanthii infection. Subcellular localization confirmed its targeting to the endoplasmic reticulum and yeast expression validated its enzymatic activity in primary alcohol biosynthesis. Heterologous overexpression of CsFAR3-like in Arabidopsis enhanced cuticular wax deposition, reduced water loss, and improved drought tolerance. Furthermore, a canonical MYB-binding site was identified in the CsFAR3-like promoter, and dual-luciferase and yeast one-hybrid assays demonstrated that CsMYB96 directly binds and activates its transcription. Heterologous overexpression of CsMYB96 in Arabidopsis increased total wax content and improved drought tolerance. Together, these findings raise the possibility of a MYB96–FAR regulatory interaction involving CsMYB96 and CsFAR3-like and imply that CsFAR3-like might be involved in cucumber cuticular wax biosynthesis and stress responses. These data provide tentative mechanistic clues for future work on improving drought resilience in cucurbit crops.