Effects of nutritional factors on the formation of Anthraquinones in callus cultures of Rheum ribes

Rheum ribes L. (Polygonaceae) is the source of one of the most important crude drugs in Asiatic regions .The medicinal character of rhubarb is due to its anthraquinone content . Different parts of sterile seedlings were cultured on MS medium to study the generation of callus. The explants were cultured with different ranges of plant growth regulators and the best range of plant growth regulators for generation of callus was IBA (1 mg l^–1) and BA (1 mg l^–1). The content of anthraquinones were determined by HPLC . The concentration of sucrose, vitamins and Myo-inositol and ratio of NO₃ to NH₄ in the medium was changed and growth rate and content of 2 anthraquinones was determined . The growth rate of callus declined with increased rate of secondary metabolites production. Myo-inositol 100 mg l^–1 in the medium increased anthraquinone content and in medium that had NO₃/NH₄:1/1 the maximum content of anthraquinone was obtained.