Effects of gamma irradiation on the alkaloid content in seeds of Datura stramonium and the radiosensitivity of derived seedlings

Abstract

Tropane alkaloids are a group of secondary metabolites occurring naturally in Solanaceae family as Atropa belladona, Datura stramonium, Mandragora officinalis, and Hyoscyamus niger. These molecules have valuable therapeutic applications, for example, atropine and hyoscyamine are utilized as antimuscarinic besides being stomach and intestinal diseases drugs. Plants of the Solanaceae family can provide a natural yet less expensive source of these compounds. Hitherto, in order to emphasize these metabolites biosynthesis, D. stramonium seeds were irradiated using a cobalt-60 source of gamma rays of 5 to 80 Gy and germinated in vitro on MS medium in growth controlled chamber. Mutagenesis of D. stramonium seeds was attempted aiming at obtaining plants from in vitro source that are genetically variable for enhancing the biosynthesis of secondary metabolites, namely alkaloids. Results indicated that D. stramonium seeds exhibited a good radiosensitivity and the mutagen damage index GR (30-50) for D. stramonium was determined at 80 Gy. The Characterization of alkaloids (Atropine and hyoscyamine) was done by infrared spectroscopy which showed that alkaloids content of the irradiated seeds is altered by irradiation as the reference bands were not found with all doses used. In addition, seedlings grown from irradiated in vitro seeds exhibited remarkable morphological variations that varied based on the employed dose of gamma rays. These findings permitted the selection of the optimal irradiation dose (80 Gy) to induce mutations that are likely to prompt changes at genetic and metabolic level of the targeted alkaloids.