We constructed a mixed-species community designed to simulate roadside and field edge plant communities and exposed it to glyphosate drift in order to test three hypotheses: (1) higher fitness in transgenic Brassica carrying the CP4 EPSPS transgene that confers resistance to glyphosate will result in significant changes in the plant community relative to control communities; (2) given repeated years of glyphosate drift selective pressure, the increased fitness of the transgenic Brassica with CP4 EPSPS will contribute to an increase in the proportion of transgenic progeny produced in plant communities; and (3) the increased fitness of Brassica carrying the CP4 EPSPS transgene will contribute to decreased levels of mycorrhizal infection and biomass in a host species (Trifolium incarnatum). Due to regulatory constraints that prevented the use of outdoor plots for our studies, in 2005 we established multispecies communities in five large cylindrical outdoor sunlit mesocosms (plastic greenhouses) designed for pollen confinement. Three of the community members were sexually compatible Brassica spp.
View Article and Find Full Text PDF• Transgenic plants can offer agricultural benefits, but the escape of transgenes is an environmental concern. In this study we tested the hypothesis that glyphosate drift and herbivory selective pressures can change the rate of transgene flow between the crop Brassica napus (canola), and weedy species and contribute to the potential for increased transgene escape risk and persistence outside of cultivation. • We constructed plant communities containing single transgenic B.
View Article and Find Full Text PDFBackground And Aims: With the advent of transgenic crops, genetically modified, herbicide-resistant Brassica napus has become a model system for examining the risks and potential ecological consequences of escape of transgenes from cultivation into wild compatible species. Escaped transgenic feral B. napus and hybrids with compatible weedy species have been identified outside of agriculture and without the apparent selection for herbicide resistance.
View Article and Find Full Text PDFIn this study, genome-wide expression profiling based on Affymetrix ATH1 arrays was used to identify discriminating responses of Arabidopsis thaliana to five herbicides, which contain active ingredients targeting two different branches of amino acid biosynthesis. One herbicide contained glyphosate, which targets 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), while the other four herbicides contain different acetolactate synthase (ALS) inhibiting compounds. In contrast to the herbicide containing glyphosate, which affected only a few transcripts, many effects of the ALS inhibiting herbicides were revealed based on transcriptional changes related to ribosome biogenesis and translation, secondary metabolism, cell wall modification and growth.
View Article and Find Full Text PDFBackground: Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds.
Methodology/principal Findings: We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments.
The importance of understanding the role of atmospheric conditions in pollen dispersal has grown in recent years with increased field-testing of genetically modified (GM) crop plants. An atmospheric model was used to characterize wind trajectories at 10 m and 100 m above GM pollen source fields located within a 4452-ha "control" area north of Madras, Oregon, USA, designated by the Oregon Department of Agriculture (ODA). The area was used in 2003 for the growth of GM creeping bentgrass (Agrostis stolonifera) engineered to be resistant to glyphosate herbicide.
View Article and Find Full Text PDFConcerns about genetically modified (GM) crops include transgene flow to compatible wild species and unintended ecological consequences of potential transgene introgression. However, there has been little empirical documentation of establishment and distribution of transgenic plants in wild populations. We present herein the first evidence for escape of transgenes into wild plant populations within the USA; glyphosate-resistant creeping bentgrass (Agrostis stolonifera L.
View Article and Find Full Text PDFWe compared three methods for estimating fungal species diversity in soil samples. A rapid screening method based on gross colony morphological features and color reference standards was compared with traditional fungal taxonomic methods and PCR-RFLP for estimation of ecological indices of soil microfungal community composition. Normalized counts of colony morphotypes on dichloran rose bengal medium were used to estimate species richness (S) and evenness (J) and to calculate Shannon's diversity (H) and Simpson's (SI) dominance indices.
View Article and Find Full Text PDFSampling methods and results of a gene flow study are described that will be of interest to plant scientists, evolutionary biologists, ecologists, and stakeholders assessing the environmental safety of transgenic crops. This study documents gene flow on a landscape level from creeping bentgrass (Agrostis stolonifera L.), one of the first wind-pollinated, perennial, and highly outcrossing transgenic crops being developed for commercial use.
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