Regulation of Α-Bergamotene Biosynthesis by the LcDOF5.8- LcTPSbms Regulatory Module in Litchi Fruit

Bergamotene, a key sesquiterpene compound, is crucial for defining the fruity aroma. However, the precise regulatory mechanisms governing its biosynthesis have been largely elusive. In this study, we elucidated that the DOF transcription factor LcDOF5.8 plays a central role in the biosynthesis of α-bergamotene by directly enhancing the expression of the terpene synthase gene LcTPSbms in litchi fruit. Our findings revealed that the concentration of α-bergamotene varies significantly among four distinct litchi cultivars: ‘Guanyinlv’, ‘Bingli’, ‘Guiwei’ and ‘Nuomici’. Notably, a strong correlation was observed between the expression level of LcTPSbms and the content level of α-bergamotene across these cultivars. Furthermore, both in vitro and in vivo catalytic assays confirmed that LcTPSbms is capable of catalyzing the synthesis of α-bergamotene. Importantly, electrophoretic mobility shift assays (EMSA) and Dual-LUC assays demonstrated that LcTPSbms is positively regulated by LcDOF5.8. Silencing LcDOF5.8 in litchi aril resulted in decreased LcTPSbms expression, whereas transient overexpression of LcDOF5.8 led to a significant upregulation of LcTPSbms and a concomitant increase in α-bergamotene biosynthesis. In summary, our research uncovers a regulatory module involving LcDOF5.8 and LcTPSbms that plays a critical role in the biosynthesis of α-bergamotene, offering valuable insights into the molecular mechanisms underlying the fruity aroma of litchi fruit.