A transgene-centred approach to the biosafety of transgenic plants: overview of selection and reporter genes

Recombinant DNA techniques have given plant breeding a new dimension. No longer hampered by crossing barriers, it is now possible to isolate genetic information from any organism and transfer it to virtually any plant of interest. Plants in which new pieces of DNA are introduced by procedures other than sexual crossing are generally referred to as genetically modified, or transgenic, plants. From the first possibilities to create such transgenic plants, however, discussions began. There is general concern with respect to the relative safety and admissibility of the transgenic plants involved. The novelty of the transgenic approach as well as the apparent concern ask for careful evaluation of the acquired characteristics of any transgenic plant (Dale et al. 1993). Research has been and is devoted to the consequences of the introduction of transgenic plants in the environment. Studies of pollen dispersal and gene transfer from transgenic crops to related species (Kerlan et al. 1992; Scheffler et al. 1993; Dale 1994; Eijlander & Stiekema 1994; Mikkelsen et al. 1996; Timmons et al. 1996; Metz et al. 1997, this issue) can be considered ‘transgene independent’, yielding information irrespective of the transgene applied. Many such ‘transgene independent’ studies conclude that specific transgenic plants should be evaluated on a case-by-case basis. This call for a case-by-case evaluation is the motivation for the alternative, or ‘transgene-centred’ approach (Nap et al. 1995) we propose here. Concentrating on the presence of gene m and gene product XXX allows definite questions to be evaluated and may identify open issues more readily than general considerations. Such a transgene-centred approach to the evaluation of biosafety should provide a useful body of knowledge reflecting the current state of affairs of gene transfer technology for regulatory authorities. That may contribute to discussions and aid in prudent policy-making regarding the transgene under scrutiny. Before embarking on such a transgene-centred approach to the biosafety of transgenic plants, it is important to determine what issues should be considered for each (trans)gene and what gene should be evaluated first.