ABSTRACT
Basic research discoveries in the 1980s related to the genomic transformation of crop species led to the commercial introduction of transgenic crops in the 1990s. In recent years molecular biologists and biochemists have begun unraveling the molecular basis of the more complex processes in plants. The past five years have seen major advances in our understanding of the biosynthetic pathways leading to the major classes of natural plant products – the phenylpropanoids, isoprenoids and alkaloids. With the cloning of the genes encoding many of the important biosynthetic enzymes involved in these complex pathways, the genetic manipulation of end products, both qualitatively and quantitatively, is now feasible. Production of the antibiotic cephalosporin C by a fungal production strain has been improved by giving increased gene dosages of a rate-limiting enzyme. Several novel antibiotics have been produced by transferring all or part of their biosynthetic pathways to heterologous host micro-organisms, as well as by targeted disruption of a biosynthesis gene (Weber et al., 1991).
