Abstract

Background/Objectives: The 3-ketoacyl-CoA synthase (KCS) enzyme is a key and rate-limiting component in the biosynthesis of very long-chain fatty acids (VLCFAs). Through controlling VLCFA production, KCS plays an essential role in plant cuticle formation. The necrotrophic fungusBotrytis cinereacan infect all aboveground parts of rose plants (flowers, leaves, and stems), causing severe economic losses. KCS restricts pathogen invasion by influencing cuticle formation and enhances tolerance to environmental stresses. While theKCSgene family has been well-studied in some plants, it remains unexplored in rose (Rosa×hybridaHort.), a species of significant ornamental and economic value. Methods: In this study, we conducted a genome-wide analysis of theRcKCSgene family in rose, identifying 18 non-redundant genes. Phylogenetic, structural, and synteny analyses were performed to investigate the evolutionary relationships, gene architecture, and duplication events. The expression patterns ofRcKCSgenes in rose petals duringB. cinereainfection were examined, and transient overexpression and silencing ofRcKCS6were used to study its function. Results:RcKCS6was found to be upregulated during gray mold infection, and transient overexpression reduced lesion size on infected petals. Conclusions: Our study provides the first comprehensive analysis of theRcKCSgene family in rose and highlightsRcKCS6as a potential candidate for improving resistance to gray mold in rose through molecular breeding.