GM – Non - GM Crops Coexistence in Western Canada : Can it Work ?

The pending approval of the unconfined release of Roundup Ready wheat in North America has brought to the attention of regulators and scientists in North America the issue of coexistence of genetically engineered (GM) and non-GM crops. In Canada, there has been great adoption by farmers of Roundup Ready and other GM canola varieties. At the time of commercial release of GM canola in Canada no specific GM, non-GM coexistence plans were considered or implemented. GM traits (transgenes) have since become ubiquitous in canola crops in Canada and this has led to some problems. For example, although Roundup Ready canola provides direct operational value to adopting farmers, controlling volunteer Roundup Ready canola in low disturbance direct seeding systems adds cost for farmers. The spread of the Roundup Ready trait in canola means that this added cost is borne by both adopters and nonadopters of the technology. The factors and conditions which led to the spread of the Roundup Ready transgene in canola in Canada appear to be similar for wheat if Roundup Ready wheat were to be released in Canada in the same way that Roundup Ready canola has been. To minimize potential negative impacts from movement of the gene conferring glyphosate (Roundup) tolerance among volunteer wheat populations after the release of Roundup Ready wheat, a coexistence plan must be created and implemented. The plan must be species and trait specific and based on knowledge of biology, ecology and agronomy. The plan must be made functional by legislation and regulation and must provide formal routes of recourse for non-adopters affected by transgene movement. Coexistence plans are progressive and will facilitate the introduction of new traits into crops both by GM and non-GM means. Introduction In Canada and the United States, approvals for the unconfined release of Roundup Ready spring wheat (Triticum aestivum L.) are pending. Roundup Ready wheat is modified through recombinant DNA technology to be herbicide-tolerant and is considered genetically engineered wheat (GM wheat). There has been some debate and controversy in North America surrounding the pending approval of Roundup Ready wheat. Proponents of this product suggest that it will simplify weed control in spring wheat, reduce herbicide injury to wheat, improve control of current herbicide-resistant weed biotypes, eliminate off-type wheat within a given wheat crop, and increase in-crop opportunities for the control or suppression of perennial weeds (Harker et al. 2003; Van Acker and Entz 2002). Those concerned about the unconfined release of Roundup Ready wheat suggest a number of risks associated with its release including difficulty and cost of controlling volunteer Roundup Ready wheat in low-disturbance direct seeding (no tillage prior to seeding) cropping systems, the evolution of glyphosate resistant weeds in glyphosate dependent cropping systems, the loss of farm saved seed for wheat (Ogg and Jackson 2001; Van Acker et al. 2003), and the adventitious presence of GM-wheat in non-GM wheat segregated for sale to satisfy domestic and export customers of North American wheat who are unwilling to purchase GM wheat (Rosher 2003). At the core of most of the concerns are questions about movement of the transgene conferring Roundup tolerance from GM to non-GM wheat crops and whether coexistence of Roundup Ready and non-Roundup Ready wheat is possible. In western Canada, Roundup Ready canola (Brassica napus L.) has been grown commercially for 8 years on large acreages. Experiences with Roundup Ready canola can be used as a valuable reference for consideration of possible intraspecific transgene movement in wheat and the creation of a functional coexistence plan for Roundup Ready and non-Roundup Ready wheat.