Development of in vitro techniques for the important medicinal plant Veratrum californicum

Veratrum californicum (Liliaceae) is an important monocotyledonous medicinal plant which is the only source of the anticancer compound cyclopamine. An in vitro culture system for somatic embryogenesis and green plant regeneration of Veratrum californicum was developed. Embryogenic calli were induced from mature embryos on induction medium. Five basal media supplemented with different growth regulators were evaluated for embryogenic callus induction, modified MS medium with 4 mg/L picloram showing the best result for embryogenic callus production. Fine suspension cell lines were established by employing friable embryogenic calli as starting material and AA medium and L2 medium as culture media. The suspension cell lines cultured in AA medium with 4 mg/L NAA appeared to be fresh yellow and fast growing. The suspension cells were cryopreserved successfully and recovered at a high rate. Green plants were regenerated from embryogenic calli maintained on solid medium with 73 % regeneration ability (green plants/100 calli) in 27-month-old culture. The in vitro plantlets contained the steroid alkaloids cyclopamine and veratramine. This in vitro system will form the basis for metabolic engineering of Veratrum cells in the context of biotechnological production of pharmaceutically important secondary metabolites.