Project description:Taxol is an efficient anticancer drug accumulated in Taxus trees. Taxus media, a large-scale cultured species, is a dioecious woody tree with high taxol yielding. However, the sexually dimorphic accumulation of taxoids in T. media is largely unknown. Our study identified a large number of differentially accumulated metabolites and differentially expressed genes, revealing the comprehensive differences between the female and male T. media trees. LC-MS analysis confirmed the high accumulation of taxoids in the female trees. Expression analysis showed that most Taxol biosynthesis-related genes were predominantly expressed in the female trees. To investigate the regulation mechanism underlying the sexually dimorphic accumulation of taxoids, a female-specific expressed gene, TmMYB39, was identified and its full-length sequence was cloned. Multiple sequence alignment and phylogenetic analyses showed that TmMYB39 is a typical R2R3-MYB factor and the subcellular localization of TmMYB39 is shown to be the nucleus. Furthermore, Y2H and BiFC assays showed that TmMYB39 interacts with TmbHLH13. Partial promoter sequences of 10 taxol biosynthesis-related genes were isolated, which were used for screening of the MYB recognition elements. TmMYB39 binds to the promoters of several taxol-related genes, such as GGPPS, T7OH, T10OH, T13OH, and TBT genes. Interaction between TmMYB39 and TmbHLH13 affected the expression of GGPS and T10OH genes, suggesting that TmMYB39 might function in the regulation of taxol biosynthesis through a ‘MYB-bHLH’ module. Our data provided a potential explanation for the sexually dimorphic accumulation of taxoids.
