Effects of Co-overexpression of Squalene Synthase and Dammarenediol-ⅡSynthase in Panax notoginseng Cells on Saponin Synthesis
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
To study the effects of the co-overexpression of the squalene synthase (SS) and dammarenediol-II synthase (DS) genes in Panax notoginseng cells on saponin synthesis, an overexpression vector of SS derived from P. notoginseng was constructed and integrated into the P. notoginseng genome by culturing with Agrobacterium tumefaciens LBA4404. Expression levels of SS and DS in transgenic cell lines were detected using quantitative reverse transcription-polymerase chain reaction (QRT-PCR), and the saponin contents were determined by the vanillin-glacial acetic acid-perchloric acid colorimetric method. The results showed that for the three strains (T-4, T-5, T-9) in which SS and DS were overexpressed simultaneously, the relative SS expression levels were 5.66, 7.37, and 7.46 times greater than that of the strain with only DS overexpression, and the relative DS expression levels were 1.39, 2.00, and 1.41 times greater than that of the strain overexpressing only DS. The total saponin content of P. notoginseng (PNS) in the three strains was 1.7 times that in the strain overexpressing only DS, and 2.4 times of that observed in normal cells. The total monomer saponin content, including R1, Rg1, Re, Rb1, and Rd, in the three strains was 1.33, 1.61, and 1.71 times greater than that in the strain overexpressing only DS, and 5.62, 6.81, and 7.26 times greater than that in normal cells. In addition, the Re content was significantly higher and reached 5–6 times that observed in P. notoginseng medicinal materials. The results indicated that both SS and DS genes played positive regulatory roles in the saponin biosynthetic pathway, and overexpression of these two genes could further enhance the saponin content, demonstrating that synergistic regulatory effects might exist for two or more genes in the biosynthetic pathway.
