New genes in alkaloid metabolism and transport.

The biosynthetic pathway of plant alkaloids is composed of several distinct enzymes of varying substrate specificities. Homology-based cloning of candidate genes and their subsequent functional testing in heterologous expression systems are accelerating the pace at which the gene catalogues of alkaloid biosynthesis are expanding. Availability of diverse genes involved in the biosynthesis, catabolism, transport, and regulation of pharmaceutically important alkaloids should steadily advance our molecular understanding of alkaloid biology and will enable us to devise more rational strategies for metabolic engineering.