FhMYB108 Regulates the Expression of Linalool Synthase Gene in Freesia hybrida and Arabidopsis

Acting as the most abundant and widely distributed volatile secondary metabolites in plants, terpenoids play crucial roles in diverse physiological regulations and metabolic processes. Terpene synthases play a decisive role in determining the composition and diversity of terpenoids. Though the regulation of terpene synthases has been extensively investigated across various plant species, limited studies have focused on the upstream transcriptional regulation of terpene synthases. In this study, we have identified linalool as the predominant volatile compound that is released gradually from Freesia hybrida flowers throughout flower blooming. In the context of the transcriptome, a typical MYB transcription factor, FhMYB108, was screened based on homologous gene comparison. FhMYB108 is capable of regulating the expression of FhTPS1, and both their expression levels showed gradual increase during flower opening. Moreover, FhMYB108 exerts a stimulatory effect on the transcription of Arabidopsis thaliana AtTPS14, while no significant increase in AtTPS14 expression is observed upon the stabilization of FhMYB108 in A. thaliana. The highly expressed AtMYC2 in A. thaliana could interact with FhMYB108 to suppress the activation of AtTPS14 by FhMYB108. The present study not only elucidates the regulatory mechanism underlying linalool synthesis but also discovers the synergistic effect of MYB and bHLH transcription factors in governing the biosynthesis of volatile terpenoids.