Silver nanoparticles as an effective stimulant in micropropagation of Panax vietnamensis —a valuable medicinal plant

Effects of silver nanoparticles (AgNPs) on somatic embryogenesis and plantlets with rhizome of Panax vietnamensis were presented in this study. The highest number of somatic embryos (140) was obtained on MS medium containing 1 mg/L 2.4-D, 0.5 mg/L NAA, 0.2 mg/L Kin and 1.6 mg/L AgNPs. Plantlets with rhizome growth enhanced on SH medium supplemented with 1 mg/L NAA and 1.2 mg/L AgNPs and limited the ethylene gas content in the culture flasks. A low concentration of ethylene gas (0.92 ppm) stimulated plantlets with rhizome growth and development, and provided positive effect on the formation and quality of plantlets. The rhizome size of the plantlets in 1.2 mg/L AgNPs treatment was larger than those in the control without AgNPs. Plantlets acclimatized on the soilless substrate were higher survival rate (93.65%) as compared to the control (44.44%) after one year in the greenhouse. In particular, the rhizome saponin content was doubled compared with that in the planlets without AgNPs after 4-year planting in the greenhouse. These results may be scaled up for micropropagation of this important medicinal plant. AgNPs improved somatic embryogenesis. AgNPs enhanced plantlets with rhizome. AgNPs limited ethylene accumulation during micropropagation. AgNPs increased the survival rate of plantlets with rhizome in the greenhouse. AgNPs increased saponin content of plantlets with rhizome.