Floral scents in higher plants play crucial ecological roles in pollinator attraction and defense, while also holding significant industrial value in perfumery and traditional medicine. Daphne odora, a highly a fragrant ornamental species in the family Thymelaeaceae, is highly valued for its distinctive floral aroma. However, the biosynthetic pathways and regulatory mechanisms underlying its scent formation remain insufficiently understood. We integrated volatile metabolome and transcriptome profiling to characterize the floral scent composition and transcriptional regulation during flower development. Terpenoids including linalool, (Z)-β-ocimene, (R)-citronellol, geranial and geraniol, were identified as the dominant volatile organic compounds (VOCs). Collectively, these compounds contribute to a dynamic fragrance profile characterized by a harmonious blend of fruity, floral, and herbal notes from blooming to withering. Among the core expressed genes associated with these VOCs, 13 members exhibited co-expression patterns with floral scent compounds. Key genes in both the MVA and MEP pathway were highly activated to form metabolic flow orientation, indicating a directed metabolic flux toward terpene biosynthesis. Additionally, seven MYB and four bHLH gene families were identified as potential upstream regulators, with DoMYB2, DoMYB38,and DobHLH26, showing potential hierarchical roles in the transcription reprogramming. Functional characterization revealed that chloroplasts localized DoTPS6, DoTPS9 and DoTPS14 may directly co-contribute to the formation of major terpenoid mixtures. This study provides a mechanistic framework for floral scent formation in D. odora. These findings could offer valuable insights for molecular breeding, fragrance engineering, and sustainable cultivation and utilization of this high-value aromatic plant.
Zhao et al. (Tue,) studied this question.