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Crop Biotech Update

Effects of GM Wheat with Resistance to Powdery Mildew on Non-target Insect Herbivores

August 5, 2011

One of the growing concerns about genetically modified crops is that they may affect non-target organisms. Thus, Fernando Alvarez-Alfageme of Agroscope Reckenholz-Tanikon Research Station in Switzerland, together with other researchers analyzed the impact of transgenic spring wheat lines with resistance to powdery mildew on insect herbivores. One of the GM lines contains Pm3b gene from hexaploid wheat, which confers race-specific resistance to powdery mildew. Another line tested had less specific resistance conferred by a barley gene that express the enzymes chitinase/glucanase. Other conventional lines of wheat, barley, and triticale were also used for comparison in the study.

For two consecutive growing seasons, the test plants were exposed to powdery mildew and several naturally-occurring insect herbivores in semi-field conditions. Mildew was found to be reduced in the GM wheat plants with Pm3b gene, but not in the enzyme-expressing line. The number of aphids was negatively correlated with mildew, with Pm3b plants containing more aphids than the mildew-susceptible controls. However, there was no significant difference in the aphid abundance of the other GM lines and their non-transgenic counterparts, probably because of the low mildew and aphid pressure in the area. The abundance and damage caused by insect herbivores cereal leaf beetle (Oulema melanopus) and barley gout fly (Chlorops pumilionis) were not affected by the GM lines.

Read the open-access research article at