CsbHLH24 and CsMYB59 Influence Terpenoid Biosynthesis in Tea ( Camellia sinensis ) by Regulating CsTPS Gene Expression

Abstract Volatile terpenoids are important components for tea aroma quality. The molecular mechanism for volatile terpenoid production in tea plants is unknown. In this study, CsbHLH24 and CsMYB59 from Camellia sinensis were functionally characterized. CsbHLH24 was predominantly expressed in tea variety “Zhenfeng Yesheng tea” (ZFYS) and highly correlated with the volatile terpene content and CsTPSs expression. The protein–protein interaction network, molecular docking, yeast two-hybrid assay, and bimolecular fluorescence complementation demonstrated that CsMYB59 directly interacted with CsbHLH24. DNA affinity purification sequencing revealed the cotarget genes of CsbHLH24/CsMYB59 proteins. CsbHLH24 and CsMYB59 were synchronously expressed with CsTPS01 and CsTPS15 and activated their expression. Transient silencing and overexpression of CsbHLH24 and CsMYB59 demonstrated their transcriptional regulatory functions on CsTPS01–CsTPS15 genes and floral terpenoids. These results suggest that the MYB–bHLH complex plays a role in the regulation of CsTPSs, thereby providing a theoretical basis for the terpenoid metabolism regulation and modification.