Genome-Wide Identification and Expression Analysis of β-Ketoacyl-CoA Synthase Family in Sugarcane (Saccharum spontaneum)

The β-Ketoacyl-CoA synthase (KCS) plays a crucial role in the synthesis of very-long-chain fatty acids (VLCFAs), regulation of stress responses, and developmental processes. However, knowledge of this gene family in sugarcane is still limited. In this study, we identified 38 KCS genes in the Saccharum spontaneum genome. Phylogenetic analysis categorized these genes into four distinct subfamilies and collinearity analysis indicated that gene family expansion primarily occurred through genome-wide or fragment replication. Almost all SsKCS promoters contained ABA-responsive, MeJA-responsive, and light-responsive elements (G-box) that are involved in regulating plant hormones and stress responses. Most of them revealed higher expression levels in seedlings compared to mature tissues. SsKCS1/10/16/17/20/37 exhibited significantly higher expression levels in the drought-resistant compared with the drought-sensitive cultivar. Moreover, we found that the wax content and the expression levels of SsKCS5/9/10/37 were also higher in drought-resistance cultivar than in drought-sensitive cultivar. Together, the first systematic analysis of the KCS family in sugarcane broadens deeper insights into their evolutionary dynamics and functional properties, and potentially provides candidate genes for sugarcane genetic improvement.