EXPRESSION OF BACILLUS-THURINGIENSIS INSECTICIDAL PROTEIN GENES IN TRANSGENIC CROP PLANTS (CORRECTED VERSION OF NT932)

The crystals and spores of Bacillus thuringiensis (Bt) have been used for many years as microbially produced insecticides with mixed success . Many of the problems of using Bt as a spray, such as environmental i nactivation of the proteins or poor crop coverage, can be circumvented by modern genetic engineering techniques. These can now be used to tr ansfer the genes for the toxic Bt crystal proteins from the bacteria i nto crop plants and so protect them from attack by economically import ant insect pests. For many years, the two major obstacles limiting the potential commercial use of transgenic plants expressing these insect icidal Bt proteins were the introduction of Bt genes into important ag ricultural species and having them expressed at sufficiently high leve ls to achieve insect control. Many of the technical limitations have n ow been overcome and the first commercial releases of transgenic insec t resistant crops, like cotton are now, or soon will be, in the hands of regulatory bodies. Transgenic seed should hopefully come on the mar ket over the next 4 or 5 years if general approval is given. One of th e major considerations that might delay commercialisation is the possi bility that insects may become resistant to the Bt proteins expressed in transgenic plants. Considerable research into the deployment of tra nsgenic Bt plants on farms and/ or in the production of multiply resis tant transgenic plants will still be needed to ensure the effective us e of this valuable agricultural resource.