In vitro propagation of an endemic and endangered medicinal plant Notopterygium incisum

An efficient system in vitro propagation for Notopterygium incisum Ting ex H. T. Chang, an endemic and endangered medicinal plant, was established to address increased demand and germplasm conservation goals. Optimum response in callus induction (CI) was observed on Murashige and Skoog (MS) medium supplemented with 1.5 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.2 mg/l 6-benzylaminopurine (BAP), which the induction rate and growth of callus were 84.44% and 0.67 g respectively. The highest shoot regeneration frequency (76.97%) and maximum number of shoots (3.6 shoots per callus) were achieved on MS medium with 1.5 mg/l BAP and 0.2 mg/l naphthalene acetic acid (NAA). Half-strength MS medium supplemented with 0.6 mg/l indole-3-butyric acid (IBA) was determined to be the best rooting medium, resulting in the maximum number of roots (18.6 roots per shoot) and the highest rooting frequency (92.28%). An approximate 83.8% survival rate among the regenerated plantlets was recorded after they were transplanted in the field at an altitude of 3200 m. An HPLC analysis showed that the content of two main chemical constituents, notopterol and isoimperatorin, in the rhizomes of 3-year-old regenerated plantlets was higher (3.84 mg/g and 4.05 mg/g, respectively) than that in commercially marketed crude drugs. This first report of complete regeneration in vitro could provide an alternative method for the rapid, large-scale production and conservation of this valuable, rare, and endangered medicinal plant.