Selection for high tropane alkaloid content in Hyoscyamus muticus plants

Egyptian henbane, Hyoscyamus muticus L. (Sol‐anaceae) is an important source of pharmaceutically valuable compounds, the tropane alkaloids. Even today these alkaloids, scopolamine and hyoscyamine, are extracted on an industrial scale from plants. We have studied the possibilities of increasing the scopolamine content in H. muticus plants by selection during several generations. The quantitative scopolamine and hyoscyamine determinations were performed on the dry leaf material by radio and enzymeimmunoassay. The increased production of these alkaloids by the progenies was an inherited attribute resulting from systematic selection for high‐alkaloid‐containing plants (inbred). The scopolamine content in the F₁ generation was increased by a factor of 3 and in the F₄ generation by a factor of 20 compared to the P generation, respectively. The year‐to‐year fluctuation among the mean scopolamine contents of the control groups was small. The maximal scopolamine content in H. muticus strain Cairo exceeded 4%, which is the highest content so far reported in the literature. When crossing the high and low scopolamine‐producing plants, the scopolamine content of the progenies was found to be intermediate between that of the two parents, thus indicating that scopolamine synthesis is inherited by the progenies from both parents. The alkaloid production of the plants grown in the greenhouse was significantly higher than those grown in the field.