Morphogenesis and alkaloid biosynthesis in cell cultures of atropa belladonna.

Callus cultures established from seedlings of Atropa belladonna L. and Atropa belladonna cultivar lutea Doll show no visible organ formation on a culture medium containing coconut milk and a-naphth-aleneacetic acid (NAA) as growth components. However, on transfer to medium without NAA they initiate both roots and shoots and continuous cultures of excised roots have been established from such roots and plants from such shoots. Segments of cultured excised roots derived from callus cultures and from seedlings were used to reestablish callus cultures on a synthetic medium and the calluses thus obtained used to initiate suspension cultures. The ability of cells in suspension cultures to exhibit morphogenesis via root or shoot or embryo-like structure formation has been exposed and examined by light microscopy. Root development is enhanced by supplementing an auxin (NAA)-free medium with either tropic or a-naphthoxyacetic acids and both these compounds can promote root initiation in the presence of inhibitory auxin levels. Callus and cell suspension cultures in the absence of visible organization contain choline but no tropane alkaloids. Atropine (hyoscyamine) can be detected in cultured excised roots, in roots initiated from suspension cultures and in plants and plantlets derived from such cell cultures. The nature and frequency of morphogenesis, and thus the alkaloid content of cell cultures, is dependent upon the composition of the culture medium, the length and number of previous culture passages through which the cultures have been propagated and (upon) the cultural techniques. The factors affecting morphogenetic expression and the suppression of alkaloid biosynthesis in organ-free cultures are discussed in relation to theories of morphogenesis in cell cultures.