Role of female-predominant MYB39-bHLH13 complex in sexually dimorphic accumulation of taxol in .

trees are major natural sources for the extraction of taxol, an anti-cancer agent used worldwide. is a dioecious woody tree with high taxol yield. However, the sexually dimorphic accumulation of taxoids in is largely unknown. Our study revealed high accumulation of taxoids in female trees using a UPLC-MS/MS method. Thereafter, many differential metabolites and genes between female and male trees were identified using metabolomic and transcriptomic analyses, respectively. Most of the taxol-related genes were predominantly expressed in female trees. A female-specific R2R3-MYB transcription factor gene, , was identified. Furthermore, bimolecular fluorescence complementation and yeast two-hybrid assays suggested the potential interaction between TmMYB39 and TmbHLH13. Several taxol biosynthesis-related promoter sequences were isolated and used for the screening of MYB recognition elements. The electrophoretic mobility shift assay indicated that TmMYB39 could bind to the promoters of the , , , and genes. Interaction between TmMYB39 and TmbHLH13 transactivated the expression of the and genes. TmMYB39 might function in the transcriptional regulation of taxol biosynthesis through an MYB-bHLH module. Our results give a potential explanation for the sexually dimorphic biosynthesis of taxol in .