Strategies for the genetic manipulation of alkaloid-producing pathways in plants

Increasingly, as a result of recent biochemical work, there exists a realistic possibility of taking a molecular genetic approach to the manipulation of alkaloid-producing pathways in plant tissue cultures. In the pathways forming indole alkaloids in CATHARANTHUS ROSEUS, tropane alkaloids in DATURA and HYOSCYAMUS species, and nicotine in NICOTIANA species, recent studies have identified a number of key enzymes and at least some of the factors that regulate their levels of activity. Such knowledge contributes the basis upon which it has become feasible to design a strategy by which the flux in these pathways may be enhanced at the genomic level. This review presents a summary of the state-of-the-art pertaining to these pathways and discusses the strategy to be adopted for a molecular approach to their manipulation, together with some of the pitfalls that may arise when trying to alter their natural regulation.