Microbial diversity in the rhizosphere of field grown herbicide-tolerant transgenic canola
In Saskatchewan it is becoming a common agricultural practice to include herbicide tolerant transgenic canola (Brassica spp.) varieties in crop rotation. These varieties provide an economic and agronomic benefit to farmers because of their ability to provide superior weed control with the use of a minimal number of herbicides. However, concerns regarding the effects of transgenic plants on soil and rhizosphere microbial communities have been raised. As part of an ongoing three-year field study we assessed the effects of field-grown transgenic canola on soil microbial diversity. Four transgenic and four non-transgenic commercial canola varieties were grown at six field locations across Saskatchewan. The rhizosphere and endophytic microbial communities were characterized through community level physiological profiles (CLPP), fatty acid methyl ester analysis (FAME) and DNA analysis. Results from the first year of our field study indicated that in some cases transgenic canola varieties supported different microbial communities than their non-transgenic counterparts, but in some cases field and soil type significantly influenced these differences. In addition, there were differences among non-transgenic varieties, which implies that microbial communities vary from plant to plant and site to site. Differences between the microbial communities of transgenic and non-transgenic plants may not be due to genetic engineering, but to soil variance.
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