Involvement of Putrescine, Nitric Oxide, and Hydrogen Peroxide in Methyl Jasmonate-Induced Ginsenoside Synthesis in Adventitious Root Cultures of Panax ginseng C.A. Meyer

Abstract

The adventitious root (AR) culture of Panax ginseng C.A. Meyer is an alternative route for mass production of ginsenosides. During the AR culture of P. ginseng, methyl jasmonate (MeJA) is frequently used as an abiotic elicitor for improving the ginsenoside production. However, knowledge on the signaling molecules involved in MeJA-induced ginsenoside synthesis is lacking to date. Therefore, the present study used MeJA to treat 30-day-old bioreactor-cultured ARs and determined the changes of ginsenosides and three signaling molecules, including putrescine (Put), nitric oxide (NO), and hydrogen peroxide (H2O2). Meanwhile, the effects of Put [(d-(-)-arginine, (d-Arg)] and nitric oxide synthase (NOS) [NG-nitro-l-arginine methyl ester (l-NAME) and S,S′-1,3-phenylenebis (1,2-ethanediyl)-bis-isothiourea (PBITU)] inhibitors and the H2O2 [catalase (CAT)] scavenger on the three signaling molecules and ginsenoside production in ARs were investigated. Results showed that MeJA promoted ginsenoside accumulation, and the maximum content of total ginsenosides was reached after 8 days of MeJA elicitation. The Put, NO, and H2O2 production increased with MeJA treatment. The Put and NO contents peaked at 12 h, whereas the H2O2 content peaked at 24 h. No obvious change (p < 0.05) was found in the MeJA-untreated control group, demonstrating that the change pattern of Put, NO, and H2O2 contents was the specificity of MeJA elicitation. In MeJA-stimulated ARs, Put and ginsenoside contents were significantly decreased with d-Arg treatment. The NOS activity and NO content and ginsenoside contents were also decreased with l-NAME and PBITU treatments. The H2O2 and ginsenoside contents were decreased with CAT treatment. These results demonstrated the enhancement effects of MeJA on the production of Put, NO, H2O2, and ginsenosides, but the increase of ginsenosides was eliminated by the inhibitor or scavenger of the signaling molecules, which proved that Put, NO, and H2O2 involved in MeJA-induced ginsenoside synthesis of P. ginseng ARs.