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Evaluating the potential ecological effects of transgene escape and persistence in constructed plant communities
Citation:
Londo, J. P., M. A. BOLLMAN, C. L. Sagers, AND L. S. WATRUD. Evaluating the potential ecological effects of transgene escape and persistence in constructed plant communities. Presented at Botany 2008 Meeting, Vancouver, BC, CANADA, July 26 - 30, 2008.
Impact/Purpose:
To date, published studies with herbicide tolerant transgenic crops have failed to demonstrate that transgene escape to wild relatives results in more competitive hybrids.
Description:
To date, published studies with herbicide tolerant transgenic crops have failed to demonstrate that transgene escape to wild relatives results in more competitive hybrids. However, it is important to consider transgene escape in the context of the types of traits, which will likely provide fitness benefits for weedy species, and which will also be under selection outside of cultivation. In order to assess the consequences of transgene persistence in non-agronomic communities, we have constructed two different plant communities in outdoor sunlight mesocosms to identify and evaluate the potential ecological effects of transgene escape from canola (Brassica napus L.) to compatible weedy relatives. The first type of constructed plant community is defined as a stacked trait community and the second is an herbivore preference and plant competition community. The combining of different types of transgenic traits into a single crop genotype, stacked transgenes, represents a recent approach to transgenic crop development. We are examining the effect of stacked transgenes (Glyphosate resistance and Bt-insect resistance), under three different selection pressures, on fitness traits in B. napus. Gene flow and hybridization ability of stacked vs. single transgene genotypes of B. napus with Brassica rapa and Brassica nigra, two sexually compatible relatives of canola, are also being compared. In a second experiment, we have constructed a field margin plant community to examine the effect of Bt-resistance transgenes in weedy populations of B. rapa on plant communities. Plant communities consist of B. rapa (+/- Bt transgene), as well as five other field margin species with varied palatability to diamondback moth (Plutella xylostella L.). The effects of herbivore resistance, insect pressure, and plant competition are examined by whole community and species level fitness measurements. The presentation details the design and establishment of the constructed communities including breeding of the experimental lines being used in the studies.