ABSTRACT
Objective: An efficient and stable regeneration system was developed to select the optimal protocol for plant regeneration with various explants of Gentiana rigescens. Methods: The study was designed as a L9(34) orthogonal experiment to explore the effects of different types and concentration of plant growth regulator combinations on adventitious shoot formation and plant regeneration, using different explants maintained on Murashige and Skoog (MS) medium after a single factor pre-experiment had been conducted. Results: Stem with buds was the optimal explant for indirect organogenesis with a frequency of callus induction of up to 97.73% obtained on MS + 6-BA 1.5 mg/L + NAA 1.0 mg/L + KT 0.05 mg/L after 10 dwith the axillary shoots starting to germinate along with the emergence of callus with a strong capacity of differentiation from the base; The callus started to generate green multiple shoots with a 100% rate after 15 d and a coefficient of differentiation in the clump shoot of 18.65. The multiplication coefficient was up to 63.58. However, the stem tip was the best explant for direct organogenesis with a propagation coefficient of up to 44.36 cultured on MS + 6-BA 0.5 mg/L + NAA 1.0 mg/L + KT 0.5 mg/L 30 days later. The plantlet derived from two explants was too weak for rooting and the weak multiplication plantlet was maintained on MS medium supplemented with 6-BA 1.5 mg/L, NAA 1.0 mg/L, KT 0.05 mg/L, and PP333 10 mg/L to rejuvenation for 60 d. The regeneration plant with 100% rooting rate was obtained by culturing on 1/2 MS + 6-BA 0.1 mg/L + NAA 2.0 mg/L for 45 d and more than 95% of plantlets survived after transplanting. Conclusion: The current study established a rapid propagation system which is helpful to protect the wild resources and high quality seedling propagation of G. rigescens, meanwhile providing scientific evidence for the research on genetic transformation.