Print PageFeral species are those that once domesticated have returned to the wild. How frequently this occurs, their ecologies outside of cultivation, or the capacity for evolutionary change among feral species are not well known. Moreover, interest in feral species has grown following the widespread adoption of genetically engineered (GE) varieties. Risks include the transfer of beneficial traits to native plants and naturalization upon escape from cultivation. The oilseed crop, canola, is of special concern in the U.S. because it is sympatric with a number of sexually compatible relatives. We undertook a study designed to document the density and distribution of escaped, transgenic canola (Brassica napus L. (Brassicaceae)) populations across North Dakota, a center for canola production in the U.S. Eleven east-west transects were conducted across the state in 2010. GIS was used to map populations and identify areas of potential risk. Sampling for feral canola was conducted with two, 1 X 50 sampling areas performed every 8.04 km along paved roadways. At each stop, all identifiable B. napus plants were counted and an individual plant was photographed, tested for the expression of transgenes and collected. The expression of two herbicide resistance transgenes was determined with commercially available TraitChek lateral flow test strips (SDIX, Newark, DE). CP4 EPSPS protein confers resistance to glyphosate herbicide (commonly known as RoundUP®). The PAT protein confers resistance to glufosinate herbicide (commonly known as Liberty Link® or Ignite®). Carbon and nitrogen isotopic composition of leaf fragments was completed on a Delta + Finnigan isotope ratio mass spectrometer.
Results/Conclusions
Results of the survey demonstrate widespread escape of transgenic and non-transgenic canola across the state with large, persistent populations being documented. Canola was detected at 46% (288/631) of the sampling locations with 80% (231/288) of this canola expressing at least one transgene for herbicide resistance. On multiple occasions mixed populations, populations containing both forms of herbicide resistance, were documented indicating that seed dispersal from different crop harvests is common. Also, two plants (0.7%) were found containing both transgenes, a trait that has not been commercially released indicating that transgenes are moving between different transgenic crop fields or in feral populations. Isotopic values contain a geographic signal suggesting that regions of the state impose greater physiological stress than others. These results indicate that some populations are more likely than others to persist and thrive outside of cultivation.
