Seeds of hope

GM technology overcomes its main drawback

Published: Tuesday 15 July 2003

-- farmers from developing countries may no longer be forced to buy expensive seeds of genetically modified (gm) plants. A new variety of gm plant will produce fertile seeds that carry desirable traits, but are incapable of spreading engineered genes into the environment.

Environmentalists have long warned about the dangers of gm plant transmitting their traits to other flora species. Genes intended to make crops resistant to weed killers have already spread to other crops on farms, notably in Canada. To avoid this, biotech companies proposed making their gm crops sterile, using the so-called 'terminator' technology. But the idea raised another problem: poor farmers would no longer be able to save seeds from one harvest to sow the following year. The resulting outcry forced biotech companies to abandon the terminator technology.

Now it is back on the agenda in the shape of a tobacco plant that can self-pollinate and produce viable seeds. The work has been accomplished at the Eastern Cereal and Oilseed Research Centre, Canada. The modified tobacco contains two extra genes in addition to those added to provide beneficial traits such as disease-resistance. Both the genes originate in bacteria. The first, from the soil-dwelling Agrobacterium tumefaciens, inhibits seed germination. This gene is directly linked to the dna that confers beneficial traits, so any seed with just the added genes cannot germinate. The second bacterial gene, from Escherichia coli, blocks the action of the first one. With both genes present, germination proceeds normally and the seeds can grow into mature gm plants and self-pollinate, generation after generation. The key feature of the gm plant is that the two bacterial genes separate when the plant makes pollen. This means that if the gm pollen fertilises a wild plant or conventional tobacco, any resulting seeds with the disease-resistant trait will also have the germinator blocker. They may inherit the second gene, but by itself this is harmless.

etc group, a Canadian lobby organisation, is not convinced of the plant's benefits. "Poor farmers will not be able to breed their own varieties from their saved seeds," asserts Hope Shand, etc's research director.

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