Presentation of the Thematic Issue on Horizontal Gene Transfer

Abstract

Questions concerning the fate and potential biological activity of transgenes from transgenic plants in bacteria have motivated considerable research that attempts to provide some answers. Some of the scientific difficulties with this research are due to the relatively low (if at all) frequencies of gene transfer from transgenic plants to environmental bacteria. Therefore, a range of different model systems have been constructed and tested in order to try to determine possible scenarios of transgene transfer to bacteria in the environment. One such model is the fate of transgenes from transplastomic plants to environmental micro-organisms, which was investigated in the frame of a European Union-funded project TRANSBAC. The objectives of this project were to understand and quantify gene transfer under optimum conditions and develop tools for reducing (or augmenting) gene transfer. A range of conditions and biological models were examined for a better overview of the probability of gene transfer. Gene transfer is expected to be a function of the genetic environment of the gene, the number of copies, its persistence in the environment, and physical conditions that increase selective pressure and enhance gene transfer. When experiments do not demonstrate measurable gene transfer, the tendency is to avoid publication. Negative results are seldom appreciated, but in a rigorous evaluation of the likelihood of different transfer events, one must recognize that the detection limits are not always sufficiently low. This was in part the motivation for engineering experimental systems to increase the likelihood of gene transfer in order to have at least a baseline (albeit maybe not an environmentally validated one).