The improvement of ginsenoside accumulation in Panax ginseng as a result of γ-irradiation

Abstract

In this study, gamma rays were used to irradiate embryogenic calli induced from cotyledon explants of Panax ginseng Meyer. After the embryogenic calli were irradiated, they were transferred to adventitious roots using an induction medium; next, mutated adventitious root (MAR) lines with a high frequency of adventitious root formations were selected. Two MAR lines (MAR 5-2 and MAR 5-9) from the calli treated with 50 Gy of gamma rays were cultured on an NH4NO3-free Murashige and Skoog medium with indole-3-butyric acid 3 mg/L. The expression of genes related to ginsenoside biosynthesis was analyzed using reverse transcription polymerase chain reaction with RNA prepared from native ginseng (NG), non-irradiated adventitious root (NAR) and 2 MAR lines. The expression of the squalene epoxidase and dammarenediol synthase genes was increased in the MAR 5-2 line, whereas the phytosterol synthase was increased in the MAR 5-9 line. The content and pattern of major ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, and Rg1) were analyzed in the NG, NAR, and 2 MAR lines (MAR 5-2 and MAR 5-9) using TLC and HPLC. In the TLC analysis, the ginsenoside patterns in the NG, NAR, and 2 MAR lines were similar; in contrast, the MAR 5-9 line showed strong bands of primary ginsenosides. In the HPLC analysis, compared with the NG, one new type of ginsenoside was observed in the NAR and 2 MAR lines, and another new type of ginsenoside was observed in the 2 MAR lines irradiated with gamma rays. The ginsenoside content of the MAR 5-9 line was significantly greater in comparison to the NG.

Biosynthesis and biotechnological production of ginsenosides

“…Moreover, heterologous expression of PgHMGR1 caused 1.8-to 2-fold increase in phytosterols, including β-sitosterol, campesterol, cycloartenol, and 2-to 2.5-fold increase in triterpenes, including α-amyrin and β-amyrin in transgenic Arabidopsis rosette leaves . Consistently, a similar result was achieved by Kim et al (2013a), and it was shown that the A. rhizogenes-mediated ectopic overexpression of PgHMGR1 caused 1.5-to 2.5-fold increase of triterpene and 1.1-to 1.6-fold higher phytosterols in Platycodon gradiflorum hairy root. These results again confirmed conserved role of PgHMGR1 in triterpene and phytosterol accumulation in plants.…”

The Integration of Metabolomics and Next-Generation Sequencing Data to Elucidate the Pathways of Natural Product Metabolism in Medicinal Plants

“…As the major physiological role of the ginsenosides is related to plant defense [198,199], stress-inducible factors have been used in order to improve their production. Treatments with methyl jasmonate and salicylic acid generally induced oxidative stress and increased ginsenoside content, as well as gamma-irradiation, which enhanced the final product up to 16-fold [200,201].…”

Plant regeneration of Korean wild ginseng (Panax ginseng Meyer) mutant lines induced by γ-irradiation (60Co) of adventitious roots

“…This has made the generation of superior genotypes by conventional breeding difficult. Therefore, attempts have been made to achieve a more rapid and increased production of the ginsenosides using other methods such as classical tissue culture [6] , bioreactor culture [7] , Agrobacterium -mediated hairy root production [8,9] , using elicitors in cell cultures [10–12] , and mutation breeding by γ-irradiation [13,14] . The last method has been used in many other plant species and has provided a large number of variants useful for plant breeding [15–17] .…”

“…The last method has been used in many other plant species and has provided a large number of variants useful for plant breeding [15–17] . Mutagenesis by γ-irradiation has been shown to enhance ginsenoside production in P. ginseng [13,14] . Recently, we have also generated mutant cell lines by applying γ-irradiation on P. ginseng adventitious roots which were derived from Korean wild ginseng root [18] .…”

“…P. ginseng is a difficult species to manipulate in vitro ; however, its regeneration has generally been accomplished using somatic embryogenesis in callus derived from mature root tissues [22–24] , callus derived from zygotic embryo [25,26] , protoplast derived from callus [27] , and cotyledons [4,28–30] . The development of efficient in vitro culture methods has facilitated the use of mutation technique for improvement of vegetative propagation of ginseng adventitious roots [13,14,18] . At present no information is available on the regeneration of a mutant adventitious root line that has been selected from γ-irradiated P. ginseng adventitious roots.…”