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Atropa belladonna is native to dry area from southwestern Europe to West Asia, and has been cultivated as an important source of the pharmacologically useful alkaloids atropine, hyoscyamine, and scopolamine. These alkaloids as plant secondary metabolites cannot be easily artificially synthesized and must be extracted from plants which are not adapted to agriculture. Production of alkaloids by in vitro cultured undifferentiated cells as an alternative to field cultivation is also difficult (Bajaj and Simola 1991), because the undifferentiated cells tend to be genetically unstable in culture and the selection of cell lines producing the alkaloids at a high level has not been achieved. In plants, alkaloids are biosynthesized in the roots and translocated to the leaves. Production of the alkaloids using root culture has been explored as a new type of in vitro culture. Root culture was facilitated by the transformation by Agrobacterium rhizogenes. Actually, in some reports on transformation of A. belladonna, the main purpose is to obtain not transformed plants but hairy roots for the study of alkaloid production (Kamada et al. 1986; Jung and Tepfer 1987; Walton et al. 1990). |
