Taxane Biosynthesis Pathway and Induction Regulation in Suspension Cultures of Taxus Chinensis Var. Mairei
|Keywords||Taxus chinensis var. mairei taxane biosynthesis elicitor inhibitor isopentenyl pyrophosphate cytochrome P-450 monooxygenase|
The metabolism pathways of isopentenyl pyrophosphate (IPP) and the important function of the cytochrome P-450 monooxygenases for taxane biosyntheses in suspension cultures of Taxus chinensis var. mairei (T) were investigated using some metabolic inhibitors. The detail studies were done from the aspects as follows.At first, some metabolic inhibitors (mevastatin, chlorocholine chloride, sodium pyrophosphate and D, L-glyceraldehyde) were added into suspension cultures of Taxus cells in order to understand the metabolism pathways of IPP for taxane biosyntheses. The results for the first time show that IPP metabolism pathways were different at the different growth phases of Taxus cells. The non-mevalonate pathway was involved in IPP biosynthesis for taxane biosyntheses at the early growth phase (0-14 day) of Taxus cells. At the late growth phase (after day 14)， the mevalonate pathway in the cytoplasm and IPP translocation were involved in taxane biosyntheses.The action mechanism of methyl jasmonate (MJ) on Taxus cells metabolism was systemically investigated by analysis of cell morphology and the solution of parameters in induction model and so on. Moreover, by using the methods of<WP=7>metabolic inhibition, the induction of MJ on IPP metabolism was studied by analyzing the inhibition ratio and induction ratio. The results suggest that MJ strongly induced the non-mevalonate pathway in 10-DAB （10-deacetylbaccatin III） and baccatin III biosyntheses at the late growth phase. In addition， MJ induced the mevalonate pathway in taxol biosynthesis. MJ stimulated IPP translocation from the cytoplasm to the plastids in baccatin III biosynthesis at the late growth phase. Furthermore， it is found that MJ did not induce IPP translocation for 10-DAB and taxol biosynthesis.Using the method of inhibitor blocking metabolic pathways, the metabolism pathways of IPP under treatment with salicylic acid (SA) were investigated compared with that of MJ. The results show that SA obviously induced the non-mevalonate pathway in the plastids for 10-DAB, taxol and cephalomannine biosyntheses and IPP translocation for taxol biosynthesis at the late growth phase of Taxus cells.The induction of MJ and SA on cytochrome P-450 monooxygenases in taxane biosyntheses was investigated by adding the specific P-450 monooxygenase inhibitor， 1-aminobenzotriazole (ABT), into suspension cultures of Taxus cells. The results indicate that the induction of MJ on P-450 enzymes was stronger at the early growth phase of Taxus cells than that of the late growth phase. Regardless of the growth phases of Taxus cells, SA induced P-450 monooxygenases in total taxane biosynthesis. However, the induction was not obvious for taxol biosynthesis.On the basis of the above studies, the metabolism model of taxane biosynthesis in Taxus chinensis var. mairei (T) was established. The changes of disturbance parameters in the model from the view of the carbon flux revealed the intrinsic mechanism of taxane biosyntheses.