By Ben Harder
Canadian researchers have demonstrated that, in principle, they can engineer genetically modified (GM) crops to be incapable of breeding with conventional crops or wild relatives. The new approach could help contain the unintended spread of artificial traits, which is a major source of public concern about GM crops.
Although several alternative strategies for such containment exist, “there is no perfect solution,” says Johann P. Schernthaner of Agriculture and Agri-Food Canada in Ottawa.
To engineer a crop that would theoretically require no intervention by farmers to keep it reproductively contained, Schernthaner and his colleagues inserted into some tobacco plants a genetic element called a seed-lethal trait. That element prevents the plants’ seeds from germinating under any circumstances.
To enable the GM plants to reproduce amongst themselves, the researchers then inserted another artificial trait that represses the seed-lethal construct. GM plants with both traits develop and reproduce normally, the researchers report in the May 27 Proceedings of the National Academy of Sciences.
To create an inherently containable GM crop, the researchers suggest that a different seed-lethal construct be placed on each member of a pair of chromosomes, so the constructs wouldn’t be inherited together. Each chromosome would also receive a repressor trait that inactivates the seed-lethal construct on the other chromosome. That way, unintended crossings of the GM crop with related plants should produce nonviable seeds because they’d contain only one of the two engineered chromosomes.
The new approach faces several potential problems, says Henry Daniell of the University of Central Florida in Orlando. For example, it’s still possible that with certain chromosomal rearrangements, both the seed-lethal and the repressor traits could spread to a non-GM plant.
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