Expression profiling of genes involved in Taxuyunnanine C biosynthesis in cell suspension cultures of Taxus chinensis by repeated elicitation with a newly synthesized jasmonate and sucrose feeding / 生物工程学报

Taxus suspension cell culture has the potential to provide a sustainable source of anticancer drug paclitaxel (Taxol) and other taxoids. In the cell culture of Taxus chinensis, Taxuyunnanine C (Tc) is the primary taxoid. To design a rational strategy for redirecting the precursor fluxes from other taxoids into paclitaxel production, we employed Real-time Quantitative PCR (RQ-PCR) to understand the dynamic profiling of key biosynthetic pathway genes of palcitaxel and taxoids during the culture process. Six genes (TASY, TDAT, T5alphaH, TalphaH, T10betaH and T14betaH) were quantified under the process condition of double elicitation by 2,3-dihydroxylpropanyl jasmonate (DHPJA) (100 micromol/L on day 7 and day 12), and sucrose feeding (20 g/L) on day 7. This process treatment led to a high accumulation of Tc at (554.46 +/- 21.28) mg/L 8 days after the first elicitation. Then 9 days after the second elicitation, Tc production was as high as (997.72 +/- 1.51) mg/L. The early pathway genes TASY and TDAT were significantly up-regulated by 182-fold and 98-fold, respectively for the first DHPJA elicitation and by 208-fold and 131-fold, respectively for the second elicitation. The induction occurred after each elicitation lasted for about 24 h before their abundances decreased. Things are somewhat different in the case of the other four genes T5alphaH, TalphaH, T10betaH and T14betaH. For gene TalphaH, it was highly up-regulated by 3061-fold for the first DHPJA elicitation and by 1016-fold for the second elicitation. For the other three genes T5alphaH, T10betaH, T14betaH, they were up-regulated by 13-fold, 38-fold and 20-fold, respectively for the first DHPJA elicitation and by 7-fold, 16-fold and 6-fold, respectively for the second elicitation. The RQ-PCR results showed that there is tight correlation between gene expression and Tc accumulation. Gene expression was in accordance with Tc yield. Elicitation could improve expression of six genes. While along with culture course, high expression of the genes weakened. Elicitation for the second time would promote high expression of the genes again.

Enhanced production of taxuyunnanine c in cell suspension cultures of Taxus chinensis by methyl jasmonate elicitation and in situ absorption / 生物工程学报

A bioprocess intensification strategy that combines both elicitation and in situ absorption was developed to improve the production of taxuyunnanine c (Tc) in cell suspension cultures of Taxus chinensis. When 100 micromol/L methyl jasmonate was added as an elicitor on Day 7, the Tc content and yield increased 3.6 and 3.3 times respectively, however the cell growth was reduced by 10%-30%. Significant improvement in Tc yield was observed when an absorbent XAD-7 was added on different time of the culture period. The optimum Tc yield was achieved when 100 g/L XAD-7 was added simultaneously with 100 micromol/L methyl jasmonate on Day 7. The maximum Tc yield of 477.4 mg/L was obtained on Day 21 of the culture, being 6.3-fold of the control and 1.9-fold of the 100 micromol/L methyl jasmonate treatment alone. In the combined treatment, 94% of the Tc produced was secreted outside of the cells and absorbed on XAD-7 absorbents. The results demonstrated that the process strategy combining elicitation and in situ absorption was effective to intensify the Tc biosynthesis via elicitation with the removal of product feedback inhibition via absorption, presenting a great potential in commercial applications.