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 t ransformation 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 produ cts which are ready or close to market introduction(1). The imminent c ommercialization of transgenic plants has generated debate about the d esirability of the transgenic products containing selectable marker ge nes, os in fact any other ancillary DNA sequences not directly contrib uting to the final product(2-6). In this review, we discuss these issu es and examine transformation systems recently developed to selectivel y eliminate particular transgene sequences from the final transgenic p lant.