Enhanced colchicine production in root cultures of Gloriosa superba by direct and indirect precursors of the biosynthetic pathway

Excised root cultures of Gloriosa superba reached 7.5 g dry wt l(-1) and accumulated 240+/-40 mug colchicine g(-1) cell dry wt after 4 weeks growth. While all precursors (except trans-cinnamic acid) enhanced colchicine content of root cultures without adversely affecting root growth, treatment with p-coumaric acid + tyramine (each at 20 mg l(-1)) increased colchicine content to 1.9 mg g(-1) cell dry wt.