Micropropagation of Lang Bian ginseng: an endemic medicinal plant

Micropropagation of Lang Bian ginseng ( Panax vietnamensis var. langbianensis ), an endemic medicinal plant, via somatic embryogenesis (SE) and rhizome formation were investigated. Rhizome explants disinfected with 0.15% AgNPs for 30 min resulted in the most effective surface disinfection (contamination, necrosis and survival with callus induction of 36.00%, 14.70% and 49.30%, respectively). Moreover, shoot regeneration (45.33%) and the number of shoots (5.2 shoots) from 0.15% AgNPs disinfected- rhizome were significantly higher than those in others after 12 weeks of culture. The leaf was cut transverse thin cell layer (L-tTCL: 1 mm × 5 mm) and petiole cut longitudinally TCL (P-lTCL: 0.5 mm × 10 mm). L-tTCL explant cultured on MS medium supplemented with 7 mg/L NAA gave 100% SE and 32.80 embryos; meanwhile, P-lTCL explants also obtained 100% SE and 51.80 embryos in 1 mg/L 2,4-D treatment. Adventitious root formation and callus induction were also observed in the auxin-supplemented treatments. In addition, 12-week-old secondary somatic embryos, mainly cotyledonary stage, were obtained from the primary somatic embryo cultured on 1/2 MS medium supplemented with 1 mg/L 2,4-D. Plantlets derived from secondary embryos grew well with 63.34% rhizome formation, 1.27 cm in rhizome length and 0.65 cm in rhizome diameter. Meanwhile, plantlets derived from adventitious shoots only induced adventitious roots and callogenesis after 20 weeks of culture. The analysis of saponins by HPLC method showed that twenty-week-old in vitro rhizomes had Rg1, Rd and Rb1.