Genome-wide identification and expression pattern analysis of the KCS gene family in barley

β-Ketoacyl CoA synthetase (KCS) is a key rate-limiting enzyme for the synthesis of very-long-chain fatty acids (VLCFAs) in plants that determines the synthesis rate and carbon chain length of VLCFAs, ultimately affecting the stress resistance of epidermal wax. In this study, a genome-wide characterization of the KCS family was conducted using high-quality barley (Hordeum vulgare L.) genome sequences. In total, 33 KCS genes were identified and were unevenly distributed in the distal centromere region of each chromosome. These genes were divided 12 subgroups based on sequence alignment and phylogenetic analysis, with members of the same subgroup possessing similar genes and motif structures. Expression analysis showed that the KCS genes demonstrate diverse tissue expression patterns in barley and also have overlapping functions. The barley KCS gene family also exhibited different response characteristics under drought stress. These results provide insights into the evolutionary processes and potential functions of the KCS gene family, offering a theoretical reference for studies on the physiological and biochemical regulation of KCS genes during barley growth and development, as well as for the genetic breeding analysis of wheat crops.