An Improved 2-step Liquid Culture System for Efficient In Vitro Shoot Proliferation of Sundew (Drosera rotundifolia L.)

An efficient procedure for in vitro shoot production of the medicinal plant sundew (Drosera rotundifolia L.) was developed. Of three cytokinins tested, zeatin (ZEA) at a concentration of 2 μM resulted in the formation of large numbers of adventitious shoots on leaf explants. A larger size of the small shoots was achieved by combining a 2-weeks preculture with ZEA (step 1: shoot induction) with a 5-weeks main culture without plant growth regulators (step 2: shoot elongation). Liquid media were superior to semisolid media: An average of 27.4 shoots per leaf explant, and 53.3 shoots per shoot explant were achieved. The 2-step culture system with liquid media permits a comparatively cheap micropropagation of sundew as well as in vitro biomass production, with potential for scale-up.