Effect of plant growth regulators and medium composition on cell growth and saponin production during cell-suspension culture of mountain ginseng (Panax ginseng C. A. mayer)

Abstract

We have established cell-suspension cultures of mountain ginseng (Panax ginseng G A. Mayer), and have attempted to increase the yield of saponin by manipulating our processing method and culturing factors (e.g., media strengths; the presence of plant growth regulators or sucrose; ratios of NO⁺ ₃/ NH^- ₄). Maximum biomass yield was obtained in media containing 2,4-D. However, saponin productivity was much higher in a medium comprising either IBA or NAA; 7.0 mg/L IBA was optimal for promoting both cell growth (10.0 g/L dry weight) and saponin production (7.29 mg/g DW total ginsenoside). Although the addition of cytokinins (BA and kinetin) did not affect cell growth, the level of saponin (particularly in the Rb group) was enhanced when the media were supplemented with either 0.5 mg/L BA or 0.5 mg/L kinetin. Half- and full-strength MS media were equally suitable for inducing both biomass as well as saponin production. We also investigated the effect of various concentrations of sucrose and nitrogen, and found that 30 g/L sucrose enhanced biomass yield as well as saponin content However, further increases (i.e., up to 70 g/L) led to a decrease in saponin accumulation and biomass production. Maximum growth and saponin productivity were reported from treatments with an initial nitrogen concentration of 30 mM. In general, the amount of saponin increased when the test media had high NO⁺ ₃/ NH^- ₄ ratios; in fact, saponin production was greatest when nitrate was the sole nitrogen source.