Science - November 11, 2004

GM potato not bad for soil life

Potatoes that have been genetically modified to resist nematodes have a negligible effect on soil life. Wageningen researchers state in Nature this week that the introduction of this crop in the homeland of the potato, the Andes, is likely to have only a very small effect on nature there, but may be able to help poor subsistence farmers improve their situation.

Scientists in Wageningen, Carolina Celis and Professor Richard Visser, worked with scientists at the Peruvian institute Senasa and the University of Leeds in England on the risks of introducing genetically modified potatoes in the Andes. They used a gene that makes potatoes inedible for the potato cyst nematode.

Greenhouse tests showed that the gene has almost no influence on organisms living in and above the soil. Field tests in England showed that the nematode population in the soil took no notice of the presence of the GM potato. The same cannot be said of fields treated with pesticides, the most common way of preventing potato diseases caused by nematodes.

The researchers also note that the spread of genes from genetically modified potatoes to local wild populations cannot be prevented, but there are ways to limit the spread. These include the use of varieties that do not produce pollen and making sure there is a buffer zone between the GM potatoes and their wild relatives. Using varieties that do not make pollen does not however stop pollen from the wild varieties from getting to the GM potatoes, and leading to seed formation.

Opponents to the introduction of transgenic crops often cite the precautionary principle as the reason for their opposition. The researchers refer in their article to advice published by the Nuffield Council on Bioethics. This think tank concludes that the precautionary principle does not take into consideration the risk of doing nothing, and that poor farmers are likely to suffer more if no action is taken. Visser: ‘You can’t exclude spread but you can limit it. Would I advocate the cultivation of GM potatoes in the Andes? It depends on the trait you introduce. We show that you should always take into account how a gene can be spread, and whether that is undesirable. For the gene we have examined, the effects are very small. Other crops have a far greater effect on flora and fauna, as does the use of pesticides.’ / KV

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