VARIATION OF TRANSGENE EXPRESSION IN PLANTS

Genetic engineering has proved to be a powerful technique for the identification of plant genes and the construction of new genetic traits of agricultural importance. A growing number of transgenic plants is available to the breeder for incorporation into breeding programmes and production of new material for the market. A prerequisite for marketing transgenic material, however, is the control of stable transgene expression. The analysis of mechanisms that influence transgene activity is therefore not only an interesting field in basic research, but also an important aspect for application. This article summarizes work on the analysis of expression variegation in transgenic petunia plants that carry the maize Al transgene. Although far from giving a final answer to the solution of the problem, the description of certain parameters involved in the regulation of transgene expression should provide some guidance for the prevention of expression variegation in transgenic plants.