Enhancement of triterpenoid saponins biosynthesis in Panax notoginseng cells by co-overexpressions of 3-hydroxy-3-methylglutaryl CoA reductase and squalene synthase genes

Triterpene saponins from Panax notoginseng are widely used in the treatment of cardio-cerebrovascular diseases with increasing demand. Herein, key enzyme genes 3-hydroxy-3-methylglutaryl CoA reductase (PnHMGR) and squalene synthase (PnSS) involved in the triterpene saponins biosynthetic pathway were introduced into Panaxnotoginseng cells to enhance triterpene saponins productions. Overexpression of PnHMGR alone or co-overexpression of PnSS and PnHMGR could remarkably enhance the accumulation of total saponins compared with the control. The highest yield of total saponins was got from the co-overexpression of PnSS and PnHMGR cell line, which was 3-fold and 1.5-fold higher than those in control and the cell line overexpressed PnHMGR alone, respectively. In addition, the contents of six major monomer saponins (Re, Rb1, Rg1, Rh1, Rh2, and F1) and phytosterols were also increased in PnHMGR-PnSS transgenic cell lines. Our results provide a useful genetic engineering strategy to improve the contents of triterpene saponins in many medicinal plants. (C) 2017 Elsevier B.V. All rights reserved.