Regeneration of plants from tissue- and cell suspension cultures of Symphytum officinale L. and effect of in vitro culture on pyrrolizidine alkaloid production

Primary calluses were induced from various organs of Symphytum officinale L. (comfrey) plants on solid MS and B5 medium supplemented with plant growth regulators. The callus was further subcultured on B5 medium. Cell suspension cultures were derived from B5 grown calluses by transfer to liquid B5 medium.