Transcriptome Profiling Reveals Specific Gene Regulation Patterns in Paclitaxel Synthesis in a Taxus yunnanensis Mutant with High Contents of Paclitaxel and 10-DABIII in Leaves and Branches

Different to wild taxus, a mutant of Taxus yunansense collected from Kunming, Yunan Province, China was found to have paclitaxel content of 0.026% to 0.067% and 10-DAB content of 0.63% to 0.95% in leaves and young branches in our previous study. In this study, transcriptome analysis of the mutant and the wild-type samples were undertaken to illustrate regulation mechanism of paclitaxel synthesis. Transcriptome profiling were launched for young branches and leaves respectively. Contents of paclitaxel and 10-DAB in the samples of the mutant and wild-types were validated across different grafting generations and different growth stages.

1. Average contents of paclitaxel and 10-DAB in the mutant were 4 folds and 32 folds higher than the wild-type, respectively, indicating the target traits of the mutant are reproducible.

2. Gene ontology (GO) analysis found out that differential expression genes (DEGs) enriched in GO terms of oxidoreductase/transferase activity, signal transducer activity, hormone metabolic process, regulation of metabolic process as well as response to stimulus.

3. Remarkable transcript abundance difference of DEGs from secondary metabolites pathway were observed in the mutant, implying a universal enhancement of secondary metabolites (including paclitaxel) synthesis pathway.

4. Negative regulation of Jasmonate (JA) signal transduction pathway was unraveled in the mutant, which was opposite to previous studies of taxus cells under exogenous MeJA induction. This result provided new insight into the potential negative JA signaling regulation on secondary metabolites in taxus, which may associate to syntheses of paclitaxel and 10-DAB.

Keywords: Taxus yunansense, paclitaxel, secondary metabolites, Jasmonate signaling, transcriptome