Transgene expression and control

The relative ease of producing transgenic plants is ail enormous experimental advantage for studies into the organization, function and evolution of plant genes and their expression systems. Transgenes are usually chimeric assemblies of cloned or synthetic DNA from diverse organisms that are introduced into plants. Using current transformation strategies their insertion sites within the plant genome are unpredictable. Although many experimental variables influence the final expression pattern of the transgene, reproducible patterns can often be achieved. Several components that are essential for predictable and efficient transgene expression have been described in the literature. The strategies and options for enhanced control of transgene expression are expanding rapidly; however, knowledge is needed in certain areas, such as the mechanism of transcription and chromatin remodeling, to fully exploit the possibilities. These areas will therefore receive greater attention in this article. The possibilities for biotechnology will grow enormously as new mechanisms for controlling transgene expression in crops species are developed.