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Transgenes Going Wild?
Risk Assessment of Transgene Introgression from Crops into Wild Relatives
Description and Aim
We could not survive and have colorful lives without domestic plants and animals. The Food and Agriculture Organization of the United Nations (FAO) predicted that we may need 70% more food by 2050 with the increasing human population, diminishing resources and shifting dietary patterns and longevity. The rapid development of biotechnology offers new opportunities for improving food security. Novel traits can be introduced more efficiently and swiftly into crops by genetic engineering than by conventional crop breeding technology. However, transgenes could escape from crops into wild relatives via gene flow and introgression. This may have unwanted ecological and evolutionary consequences in wild populations, depending on the nature of the transgene and its effect. The European Food Safety Authority (EFSA) will soon, probably in 2012, update the guidance on Environmental Risk Assessment (ERA) of Genetically Modified (GM) plants. Therefore, the objectives of the workshop were to:
1) Present relevant research findings about transgene introgression risk assessment;
2) Discuss the most effective methodology for transgene introgression risk assessment;
3) Make suggestions for risk assessment frameworks.
The workshop gathered 40 participants in the Lorentz Center including ecologists, molecular biologists, population geneticists, environmental scientists, mathematicians and policy makers from seven European countries, United States and China. In particular, policy makers from EFSA attended the workshop. Dr. Ellstrand from University of California at Riverside, who initiated studies about crop-wild hybridization and its consequences 10 years ago, gave a nice summary talk of this field. New case studies in carrot, oilseed rape, radish, rice, and lettuce were presented. New molecular methods were introduced for detecting crop-to-wild introgression in nature. The roles of mathematical modeling in understanding the mechanisms of introgression and in estimating the risks of transgene introgression were discussed. The new EFSA guidance for risk assessment of GM plants was introduced and discussed. There were lively active interactions among the participants during the workshop. Many new ideas were produced in the group discussions. New cooperation networks have been established.
In general, we agreed that hybridization and gene flow between crops and their wild relatives had occurred for a very long time since the beginning of the crop domestication (10 thousand years ago). Gene flow itself is a neutral process and does not need to have adverse consequences. Therefore, from the point of view of risk assessment, where risk = hazard ´ exposure, gene flow is not necessarily a risk. Introgression is the permanent incorporation of genes from one set of differentiated populations into the other. Introgression involves not only hybridization and gene flow but also the genes need to be incorporated into new populations. Scientists tended to believe that spontaneous introgression had occurred from many crops into one or more wild populations somewhere in the world though solid evidence, excluding alternative explanations, was rare. With the new high-throughput sequencing and genotyping technologies, conclusive evidence about crop-to-wild introgression can be found. Still, introgression may not be evolutionarily or ecologically significant leading to a possible “hazard”. Crop-to-wild introgression usually results in increased genetic diversity of wild populations, but only occasionally leads to the evolution of increased weediness/invasiveness or extinction risks. There were well-substantiated reports of more than 14 transgene events “escaping” into the “wild” but they were mostly in agriculture fields or along the road sides under strong human disturbances. Crop-to-crop transgene flow generally should occur more often than crop-to-wild gene flow and should receive more consideration. We should focus more on the possible “hazard” of introgression for risk assessment. Mathematical modeling can provide powerful tools for risk assessment and management but we need to be very careful not to overestimate the power of modeling. For regulations, there is a tendency to ask for more detailed data for risk assessment and management, but we need to keep in mind that what we need to know and what data are indeed necessary. Based on the outcomes of the workshop, we decided to write three publications together to summarize the workshop and to provide guidance for both scientific researchers and regulations in the future.
We are very grateful to the Lorentz
Center for great supports to our workshop, especially Corrie Kuster, Sietske
Kroon, Dr. Henriette Jensenius and Dr. Mieke Schutte. We thank all participants
for their contributions to the workshop, all the brilliant ideas in the
presentations of the speakers and during the discussion sessions. We thank
co-organizers Dr. Klaas Vrieling,
Jun Rong (Leiden, Netherlands)
Patsy Haccou (Leiden, Netherlands)
Tom de Jong (Leiden, Netherlands)
Allison Snow (Columbus, USA)
Detlef Bartsch (Berlin, Germany)
Bao-Rong Lu (Shanghai, China)
Geert De Snoo (Leiden, Netherlands)
Hans Bergmans (Bilthoven, Netherlands)