Low dose gamma radiation increases the biomass and ginsenoside content of callus and adventitious root cultures of wild ginseng (Panax ginseng Mayer)

Mountain ginseng (Panax giaseng Mayer) is known as the most valuable herb around the world. Several biotechnological tools have been developed to enhance the production of secondary metabolites in medicinal plants, especially mountain ginseng. Mutagenesis is used to create desirable mutations at the genetic level. Among several energy sources used in mutant breeding programs, gamma rays are considered the most common and efficient tool for mutagenesis. Gamma rays are preferred over other energy sources because of convenient operation, short cycle, and high mutation frequency. In this study, gamma rays were used to generate mutant adventitious root lines of P. ginseng with high biomass and ginsenoside content. Callus and adventitious root cultures of P. ginseng, which were in culture short-term (1 year) and long-term (20 years), were irradiated with various doses of gamma rays. Exposure to higher doses of gamma rays caused necrosis in long-term explants. Four mutant lines of adventitious roots were identified with unique RAPD markers using eight primers. The genetic similarity among mutant lines ranged from 0.67 to 0.96. We also analyzed the total ginsenoside content and levels of 12 individual ginsenosides using HPLC analysis. The total ginsenoside content was 4.2-fold higher in mutant lines than in the control. The mutant line 1G-20-19 showed the highest ginsenoside content compared with the untreated control and other mutant lines. Overall, mutant lines of adventitious roots by gamma ray treatments in this study represent good candidates for commercial production of ginsenosides.