Enzymology of Alkaloid Production in Plant Cell Cultures

The art of plant cell culture has developed in the past 15 years to such an extent that we can now recognize at least four categories of cell or callus cultures with regard to their ability to produce secondary plant products: a) cultures which invariably produce the compounds in question (e.g. anthraquinones in the case of Morinda, Galium, etc.), b) cultures which contain variant cells producing compounds in the presence of a majority of non-producing cells (e.g. ajmalicine and solasonine in the case of Catharanthus or Solanum (3)), c) cultures which invariably do not produce the compounds which are elaborated by the original differentiated plant (e.g. morphine, scopolamine in Papaver somniferum (4) and Datura, respectively), d) cell cultures which produce compounds which are not found in the differentiated plant (5). The handicap for the commercial use of plant cell cultures is the fact that the majority of medicinal plants yield cell cultures which are unable to produce the desired compounds (e.g. codeine, digoxin, ginkgolides, morphine, pilocarpine, quinidine, scopolamine, sennosides). The plant systems which would yield these highly priced and necessary compounds have been studied extensively in this and other laboratories without success. The most important question is how to achieve in suspension cultures chemical differentiation without morphological differentiation.