Tropane Alkaloid Production in Hyoscyamus Root Cultures

Abstract

Tropane alkaloid production was studied in callus and root cultures of seven Hyoscyamus species. Cultured roots grew well (2- to 6-fold in 8 days) without addition of growth regulators. Hyoscyamine content in these roots varied from 0.04 % DW to more than 1.1 % DW, and scopolamine content from 0.06 % DW to 0.3 % DW, depending on the plant species. Calli grew slowly (2- to 7-fold in 4 weeks) and had much lower alkaloid content than their respective root cultures. Hyoscyamine was the main alkaloid in all callus cultures. Alkaloid production in root cultures of H. niger and H. albus was studied under various culture conditions. When roots were cultured in medium without growth regulators, the main alkaloids produced were scopolamine (0.2% DW) in H. niger and hyoscyamine (0.5 to 1.2% DW) in H. albus. In H. albus root cultures, an inverse relationship between growth and hyoscyamine content was found. Auxin, especially IBA at 10 −6M to 10 −4M, stimulated growth of the root cultures, which was accompanied by increased lateral root induction. Alkaloid biosynthesis, however, was inhibited as auxin concentration increased. In H. niger root culture, scopolamine formation was inhibited by auxin more strongly than hyoscyamine formation. These effects of auxin on growth and alkaloid biosynthesis were confirmed in Datura, Atropa and Duboisia root cultures. Effects of other growth regulators and several basal media were also examined.