β-ketolipoyl coenzyme A synthase (KCS) is an essential limiting catalyst involved in carbon chain elongation during fatty acid biosynthesis, characterized by strict substrate specificity. C18:1 (oleic acid) plays a vital role in cell membranes and is essential for nutrient storage and stress defense. There are indications of significant accumulation and rapid synthesis of C18:1 during the early growth stages of L. episperm. The gene family in has yet to be analyzed, and the role of in oleic acid synthesis remains unexplored. : In this study, this issue was investigated using transcriptomic and metabolomic data, bioinformatics analysis to screen a key gene from the gene family, and dual validation using yeast and Arabidopsis thaliana expression systems to probe its function. : A total of 11 members of the gene family were identified, and the dynamics of these genes were analyzed during exocarp development in the genome. Among them, the gene designated showed a highly direct association with the content of C18:1. Heterologous expression of in yeast increased C18:1N12 and C18:1 content by 3.18-fold and 2.07-fold, respectively. Overexpression of in Arabidopsis showed that C18:1 was increased by 27.70% and 31.43% in and strains, correspondingly, in juxtaposition to the non-transgenic plants. In addition, the content of VLCFAs increased to varying degrees. : These outcomes offer important insights for investigating the role of genes in fatty acid synthesis to further improve resistance.