Conventional, certified canola seedlots were contaminated with genetically
Canola (Brassica napus).
Several genetically engineered (GE) canola lines have been developed with
herbicide resistance traits. Resistance to the herbicide glyphosate
(Roundup) has been engineered with a combination of two genes: (1) a gene
from Agrobacterium strain CP4 that produces a resistant form of
the EPSPS enzyme targeted by glyphosate, and (2) a modified glyphosate
oxidase gene from the bacterium Ochrobactrum, which accelerates
the degradation of glyphosate. Resistance to the herbicide glufosinate
(Liberty) has been engineered using Streptomyces bacterial genes
for the PAT enzyme, which inactivates glufosinate.
Goal of This Study:
"This survey of the purity of pedigreed canola seedlots with respect
to herbicide resistance traits was prompted by complaints from several
farmers regarding glyphosate-resistant canola volunteers occurring
unexpectedly in their fields at densities and in patterns that suggested
that pollen-mediated gene flow from neighboring fields in previous years
was not the source of contamination" (p. 1343).
Results of This Study:
Either glyphosate- or glufosinate-resistant canola plants were
detected in all 16 of the conventional (non-GE), certified canola
In 8 of the 16 seedlots, the concentration of GE seed exceeded 0.25%,
which is the maximum amount of contamination allowed in certified seed.
"The results of this study indicate that the pedigreed canola seed
production system in western Canada is cross-contaminated with the various
herbicide resistance traits at a high level and that purchasing and
planting a pedigreed conventional canola seedlot does not guarantee the
absence of genetically engineered traits. For those producers that grow
canola and practice direct [no-till] seeding, it means that glyphosate
no longer is a nonselective, broad-spectrum herbicide that can be used
alone as a spring burn-off treatment" (p. 1346). Growers have been
responding to this situation by using additional herbicides to achieve
broad-spectrum weed control.
Friesen, L. F., A. G. Nelson, and R. C. van Acker (2003). "Evidence of
Contamination of Pedigreed Canola (Brassica napus) Seedlots in
Western Canada with Genetically Engineered Herbicide Resistance Traits,"
Agronomy Journal vol. 95, pp. 1342-7.
University of Manitoba, Canada.
Genetically engineered canola is grown on millions of acres in the US and
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