Chimeras in context: An ecological approach to understand the fate of transgenes in and out of maize.

摘要

The widespread release of genetically modified (GM) crops continues despite a lack of basic scientific understanding of the implications for human health, the environment, and food security. As scientific knowledge on gene expression continues to evolve, new perspectives are necessary to conceptualize how transgenes behave in different biological and ecological contexts. In this thesis, an ecological approach was used to investigate the fate of transgenes in and out of GM Maize to better understand their potential ecological and evolutionary consequences.;Ecological approaches help determine what the "relevant" questions are for GM biosafety research that have been historically lacking. I conducted a molecular analysis of a commercial variety of MON810 transgenic maize, and found an unexpected rearrangement and interspersion of both genomic and plasmid DNA within the construct that was not reported by the developing company. The results highlight the need for accurate information on GM crops for effective and useful post-release biosafety monitoring.;From there, investigations into different routes of gene movement---whether vertically (through inheritance), or horizontally (to microbial associates)---can be better informed. Here I report evidence of vertical transgene introgression into traditional varieties of Mexican maize in Oaxaca, Mexico, and discuss the implications of the controversial scientific discourse that followed the publication of this work. For horizontal gene transmission, I investigated the potential transfer of transgenic DNA from GM maize to its common fungal pathogen, Ustilago maydis. Low frequency transfer of transgenic sequences was detected, suggesting the possibility that bulk DNA transmission to the pathogen is a viable source of secondary form horizontal gene transfer (escape) of heterologous DNA.;These results can then be used in biosafety research to address the potential ecological and evolutionary significance GM crops. Lastly, I synthesize my dissertation findings and their utility in designing effective GM crop regulatory policy, and discuss a way forward for biosafety research using an ecological approach to studying the metaphorical epigene. In this light, asking relevant questions on the safety of GM crops, in a new conceptual milieu, may offer new insights for basic biology and biosafety for a sustainable ecological and agronomic future.