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2-Plants: US workshop on risk assessment -

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Information Systems For Biotechnology 
National Biological Impact Assessment Program

March 1999

News For The Agricultural And Environmental Biotechnology Community 



A diverse group of about 70 scientists, regulators and research managers gathered in Bethesda, MD early last month to take part in a workshop on "Ecological Effects of Pest Resistance Genes in Managed Ecosystems." The meeting, organized by Information Systems for Biotechnology, brought together ecologists, plant breeders, U.S. and foreign biotechnology regulators, population biologists, weed scientists, plant pathologists, regulatory affairs managers and entomologists.

Their task was to address an important risk assessment issue for crops that have wild or weedy relatives: Does the introduction of pest resistance into a crop species, whether by conventional breeding or by recombinant DNA methods, affect the establishment, persistence, and spread of the crop or sexually compatible species?

Workshop objectives were (1) to review existing evidence that introduced pest resistance traits affect weediness characteristics of either the crop or related species, and (2) to identify strategies to obtain such information where it is lacking. Plenary talks provided background information and set the stage for subsequent interdisciplinary discussions in small breakout groups.

Each breakout group focused on a crop that has wild or weedy sexually compatible relatives growing in the U.S., and that is or will likely be genetically engineered for pest resistance. Prior to the workshop, participants were organized into groups addressing berries, brassicas, cereals (rice and wheat), cucurbits, turf grasses, poplars and sunflowers. Under the coordination of a group leader, they assembled a summary of information pertaining to the major pests and diseases of the crop; weed complexes associated with the crop; pest resistance traits introduced either by breeding or genetic engineering; the type of crop management system and degree of domestication of the crop species; and weed management strategies for the crop and its sexually compatible relatives.

At the workshop, participants met in breakout groups to address the objectives using guidance questions as a framework for their discussions. For the first objective, groups were asked to consider:
- What is the evidence that introduction of a pest resistance trait could increase the ability of the crop to become established, persist, or spread?
- What is the evidence that pests have a significant effect on populations of plant species that are sexually compatible with the crop? Are any such pests common to both the crop and the sexually compatible species?
- If the crop is made resistant to such pests, what are the potential consequences of the pest resistance trait moving from the crop to the sexually compatible relatives? How likely is introgression of the resistance trait?

Questions to address the second objective were:
- What specific information is not currently available, but would be important in providing a stronger scientific basis for evaluating the effect of pest resistance genes on the establishment, persistence and spread of the crop or its sexually compatible relatives?
-What are the available sources and/or experimental approaches that would provide such needed information?
-What characteristics of the crop affect our ability to extrapolate from small-scale field tests to large-scale use in terms of evaluating its establishment, persistence and spread?

All participants met on the final morning of the workshop to share the results of their discussions. Considering the diversity of viewpoints, there was a surprising amount of agreement on the basic conclusions. Most groups found little or no risk of enhanced weediness from pest resistance genes already in use. From an ecological point of view, transgenic crops engineered with one or a few protective genes are essentially the same as conventionally bred crops having the same phenotype. Compared with varieties improved through breeding, today’s genetically engineered crops do not pose new risks.

However, advances in technology and approaches to engineered pest resistance, such as gene stacking to confer resistance against a multitude of pathogens or pests, raised concerns for most participants. Such broad spectrum pest deterring power may have high selective value and lead to ecological consequences which are less predictable than the relatively limited pest resistance traits that constitute much of our experience to date.

Participants agreed that little was known about the ecology of crop-weed complexes, and this shortcoming hampered informed decision making. Recommendations for risk assessment research priorities will be included in the group reports.

Many participants found the multidisciplinary science-based approach used in this workshop to be surprisingly effective in bridging gaps between the disciplines and stimulating new ideas for research. The format could well serve as a model for similar evaluations of other crop-weed systems in the U.S. as well as other countries.

The findings of the workshop will be useful to those who set research priorities, plan breeding programs, make regulatory decisions, or address public concerns regarding the use of genetically engineered crops. A Workshop Proceedings, due out in June, will include papers by the plenary speakers and reports and recommendations from each breakout group. It will be published on the ISB website (; print copies will be available upon request to Pat Traynor (; 540-231-2620). 

-| Hartmut Meyer
-| Co-ordinator
-| The European NGO Network on Genetic Engineering
-| Reinhaeuser Landstr. 51
-| D - 37083 Goettingen
-| Germany
-| phone: #49-551-7700027
-| fax  : #49-551-7701672
-| email:

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