Integrated transcriptome and metabolome analyses reveal the mechanism underlying the transition of flower color in the rose cultivar 'Juicy Terrazza'.

Flower color is a prominent ornamental characteristic in roses. In this study, the petal development of the rose cultivar 'Juicy Terrazza' was categorized into three stages: tangerine-colored petals in the flower bud (JT-T), orange-colored petals of the blooming flower (JT-O), and pink-colored petals of the open flower (JT-P). We utilized transcriptomics and and metabolomics approaches to investigate the genes involved in the pigment metabolic pathway of rose petals. We utilized transcriptomics and metabolomics approaches to investigate the genes and metabolites involved in the pigment metabolic pathway of rose petals. A total of 872 metabolites were identified in rose flowers. Comparative analysis revealed significant differences in 153 accumulated metabolites between open flowers in JT-P and flower buds in JT-T. The flower coloration of this rose cultivar is primarily influenced by carotenoids and anthocyanins, with carotenoids being the main differential metabolites responsible for altering the flower colors during the transition from JT-T to JT-P. Furthermore, by conducting a comparative study on differentially expressed genes (DEGs) during the transition of petal color, potential candidate genes related to this specific phenotypic characteristic were successfully identified. PSY, PDS, ZISO, and ZDS genes showed significant downregulation, while RcCCD4 exhibited strong upregulation in JT-P compared with JT-T, which could directly contribute to the reduction of carotenoid contents during the JT-P stage. These findings contribute to our understanding of the impact of specific metabolites and transcripts on flower color changes and the molecular mechanisms of carotenoid metabolism and flavonoid biosynthesis in rose flowers.