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The influence of the environment on genetically modified wheat

Differences between greenhouse and field trial results

In the greenhouse, lines of genetically modified wheat carrying a resistance gene against the fungal disease mildew have a yield which is up to twice as high as that of control plants. In the field however, this ratio is reversed for certain, but not all, wheat lines. A study performed within the National Research Programme «Benefits and Risks of the Deliberate Release of Genetically Modified Plants» (NRP 59) concludes from these results that data from the greenhouse cannot be applied to the situation in the field and that therefore field trials are important.

Thanks to a natural resistance gene from an old Asian wheat variety genetically modified wheat is more resistant to the fungal disease mildew, also in the field. But in field trials, some wheat lines show a reduced yield or a modified ear shape, which had not been observed in the greenhouse. Such accompanying variations have been known for some time in breeding processes, but now, for the first time, researchers working at the University of Zurich have described in PLoS One (*) how significant the differences between greenhouse and field trials really are.

Reduced yield In the greenhouse, where many plants are a target for mildew when not treated with fungicides, the genetically modified wheat has an advantage due to its enhanced resistance. Its yield is up to twice as high as that of the untreated non-transgenic control plants. In the field however, the wheat plants are up against droughts, insect infestation and competition with other plants. In this environment, the genetically modified wheat plants are still more resistant, but this leads to a drop in yield for some wheat lines. Furthermore, in field trials the ears of certain genetically modified wheat lines take on a different shape, which favours infestation with rye ergot, another fungus. These side effects do not show up in some wheat lines, in others the degree of the effects varies. This might have to do with variations in the position and activity of the resistance gene.

Field trials are necessary The experiments show that it is not always possible to identify plants which will be able to assert themselves in a natural environment by performing trials in the protected setting of a greenhouse. The complex relationships between plants and their environment are only revealed in field trials.

(*) Simon Zeller, Olena Kalinina, Susanne Brunner, Beat Keller und Bernhard Schmid (2010). Transgene - Environment Interactions in Genetically Modified Wheat. PLoS One, online: http://dx.plos.org/10.1371/journal.pone.0011405

National Research Programme «Benefits and Risks of the Deliberate Release of Genetically Modified Plants» (NRP 59) Within the NRP 59, researchers active in a total of 29 research projects are investigating the benefits and risks of genetically modified plants with regard to the ecological, social, economic, legal and political situation in Switzerland. In one of these projects, an association of research groups belonging to various higher education institutions - the wheat-cluster.ch - is analyzing the fungal resistance of genetically modified wheat in a field trial at the Agroscope Reckenholz-Tänikon ART research station. www.nrp59.ch

Contact: Prof. Bernhard Schmid Institute of Evolutionary Biology and Environmental Sciences Universität Zürich Winterthurerstrasse 190 8057 Zürich Phone: ++41 (0)44 635 52 05 E-mail: bernhard.schmid@ieu.uzh.ch

This press release is available at the Swiss National Science Foundation website: www.snf.ch > E > Media > Press releases

idw :: 13.07.2010