Tissue Culture of Plagiochasma appendiculatum and the Effect of Callus Differentiation on Types and Content of Bisbibenzyls

Plagiochasma appendiculatum, a thalloid liverwort, contains high levels of bisbibenzyls, aromatic compounds with potent antitumor as well as antifungal activities. In the present study, rapid growth callus was induced from the thallus of P. appendiculatum, and optimal culture conditions, including medium, temperature, pH, and plant growth regulators for callus production were evaluated. Under optimal culture conditions, the biomass of the callus doubled with a sigmoidal growth curve after 15 days. Differentiation and plant regeneration were studied on a medium supplemented with different plant hormones (α-naphthaleneacetic acid [NAA], 6-benzyladenine [6-BA], and 2,4-dichlorophenoxyacetic acid [2,4-D]). NAA and 6-BA stimulated rhizoid and thallus differentiation, respectively, whereas 2,4-D inhibited the differentiation of thallus and rhizoid. Different metabolic profiles of callus, differentiated thallus, and thallus in the soil were studied by high-performance liquid chromatography. The results showed that both the callus and thallus could synthesize bisbibenzyls. In addition, the kinds and content of bisbibenzyl differed significantly between the callus and thallus. In conclusion, P. appendiculatum thallus cultured in vitro possesses the ability to biosynthesize bisbibenzyl, and it may be utilized for the mass production of specific bisbibenzyls in an appropriate growth environment.