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Glyphosate drift promotes changes in fitness and transgene flow in canola (Brassica napus) and hybrids
Londo, J. P., N. S. Bautista, C. L. Sagers, E. LEE, AND L. S. WATRUD. Glyphosate drift promotes changes in fitness and transgene flow in canola (Brassica napus) and hybrids. Annals of Botany. Oxford University Press, Cary, NC, 106(6):957-965, (2010).
With the advent of transgenic crops, genetically modified, herbicide resistant B. napus has become a model system for examining the risks of escape of transgenes from cultivation and for evaluating potential ecological consequences of novel genes in wild species.
1. With the advent of transgenic crops, genetically modified, herbicide resistant B. napus has become a model system for examining the risks of escape of transgenes from cultivation and for evaluating potential ecological consequences of novel genes in wild species. 2. We examined the effects of a drift level (1/10ththe field application rate) of glyphosate herbicide and varied levels of plant competition on plant fitness traits and gene flow in a common garden experiment that included transgenic, glyphosate resistant B. napus, its weedy ancestor B. rapa, and hybrid and advanced generations derived from them. 3. These experiments demonstrated an overall reduction in fitness due to glyphosate drift in the weedy B. rapa species, and a contrasting increase in plant fitness for transgenic genotypes. Additionally, the selective pressure of drift level glyphosate contributed to significant changes in the pattern of gene flow within the plant community. 4. Drift-level glyphosate appears to have altered the flowering phenology of B. rapa and contributed to a decrease in transgenic seed numbers on B. rapa plants relative to control plants. Concurrently, gene flow to F1 hybrids increased under selective pressure resulting in an increase in transgenic seeds. 5. These results suggest that a drift level of glyphosate spray can influence the movement of transgenes among transgenic crops and weeds and alter the processes of hybridization and introgression in non-agronomic habitats. 6. Synthesis and applications. Glyphosate pressure extends beyond crop field boundaries, and a drift-level of glyphosate functions as a selective agent on the fitness of nearby weedy species. Escape and persistence of transgenes to wild and weedy species can be impacted by the effects of glyphosate spray drift both by direct reductions in plant fitness and by alterations in the dynamics of gene flow between compatible crops and weeds.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY
WESTERN ECOLOGY DIVISION
ECOLOGICAL EFFECTS BRANCH