TRANSFORMATION SYSTEMS FOR GENERATING MARKER-FREE TRANSGENIC PLANTS

The ability to efficiently introduce foreign genes into plants is key to the success of the emerging plant biotechnology industry. Genetic transformation of crop plants is becoming increasingly routine both in terms of the number of plant species which can be transformed and the frequency of transformation, resulting in a number of transgenic products which are ready or close to market introduction(1). The imminent commercialization of transgenic plants has generated debate about the desirability of the transgenic products containing selectable marker genes, os in fact any other ancillary DNA sequences not directly contributing to the final product(2-6). In this review, we discuss these issues and examine transformation systems recently developed to selectively eliminate particular transgene sequences from the final transgenic plant.