Genome-wide analysis of the KCS gene family in Medicago truncatula and their expression profile under various abiotic stress

Very long-chain fatty acids (VLCFAs) are indispensable constituents of cuticular wax and exert pivotal functions in regulating plant growth, development and response to stress. β-Ketoacyl-CoA synthase (KCS) represents the rate-limiting enzyme for the biosynthesis of VLCFAs. In this study, 25 KCS genes were identified in the M. truncatula genome and were unevenly distributed across seven of the eight chromosomes. The 25 MtKCS genes were clustered into seven groups, each exhibiting conserved gene structure and motif distribution. MtKCS gene promoters contained multiple hormone signaling and stress-responsive elements, indicating that the expression of these genes may be modulated by a range of developmental and environmental stimuli. The expression profiles revealed that the MtKCS genes exhibit diverse expression patterns across various organs/tissues and are differentially expressed under abiotic stress. It is noteworthy that several genes, such as MtKCS2, 10, and 13, exhibited significantly increased expression in leaves under cold, heat, salt, and drought stress. This suggests that MtKCS genes may play an integral role in the abiotic stress resistance of M. truncatula. These findings establish a foundation for understanding the evolution of KCS genes in higher plants and facilitated further functional exploration of MtKCS genes.