Jul 26, 2010
Results of the safety research
Fungus-resistant barley – No effects on beneficial fungi
Genetically modified barley, which through the introduction of new genes is resistant to harmful fungi, does not negatively affect beneficial fungi or therefore plant growth. In addition, according to the results of a multi-year study at the University of Giessen, it appears that targeted gene modifications affect plants far less than classic breeding or environmental factors. From 2005 to 2010 in the course of biosafety research, two genetically modified barley lines were tested in the field, greenhouse and laboratory. GMO Safety spoke with Karl-Heinz Kogel from the University of Giessen.
“The result is that genetically modified plants are also colonised by beneficial mycorrhiza fungi.” Prof. Karl-Heinz-Kogel, Institute for Phytopathology and Applied Zoology (IPAZ) of the Justus-Liebig University Giessen in interview with GMO Safety
Barley on the trial field under a safety net. Considerable areas of the release area were repeatedly vandalised by gene technology opponents.
Small barley plants on culture medium
Barley in the greenhouse
Barley naturally forms glucanases and chitinases. However, during the plant’s development the corresponding genes are activated so late that its defence is not sufficient to combat pests in time. Glucanases from barley have already been introduced into other organisms such as vines so that they attain fungal resistance.
The hyphal networks of the beneficial mycorrhiza fungi are visualised under a microscope with staining techniques.
Fungal infections, particularly Fusarium fungi, are a frequent problem in crop growing. Some Fusarium strains produce highly toxic metabolites, so-called mycotoxins, that can mix with the harvest and can cause great problems for example for animal feed and in the beer breweries. However, barley is less susceptible in comparison to wheat, oats or maize.
Two safety research projects supported by the Federal Ministry for Education and Research have looked at genetically modified barley that possesses increased resistance against fungi. These barley strains were developed at the Washington State University and have already been tested in the field.
Two barley lines were investigated:
- Into one of the two lines a gene was introduced that originated from a soil fungus (Trichoderma harzianum) and formed a chitinase. This fungus has been used for many years as a biological plant protection. Chitinases break down chitin which is also a component of the cell walls of fungi.
- In the second line a gene from a soil bacterium (Bacillus amyloliquefaciens) was introduced that forms glucanase. The gene was transferred to barley to improve the brewing characteristics and the digestibility in animal feed. Glucanases also have fungal resistance properties – it destroys certain fungi.
One of the research projects investigated whether the formation of chitin- and glucan-degradation enzymes also damaged beneficial fungi. Approximately 70–80% of outdoor plants live symbiotically with so-called mycorrhiza fungi, through which the plant and fungi benefit one another. The fungi supply the plants with nutrients such as phosphate, and the plants offer the fungi a protected habitat and also provide them with carbohydrates.
In long-term trials in the greenhouse and outdoors, no differences in the colonisation through the beneficial mycorrhiza fungi were seen between the transgenic and non-transgenic barley plants. In the laboratory, the amounts of mycorrhiza fungi in the roots were exactly recorded using molecular analyses. To determine whether these fungi were still functional in the genetically modified plants, i.e. they still supported plant growth, the structures of the fungi were microscopically examined. It was shown that the formation of the hyphal networks and the nutrient-providing cells (arbuscles) were not affected by the gene technological modification.
A further project looked at the question of whether the formation in the plant of both these fungus-targeting enzymes had other undesired effects on the plant characteristics and components. It was shown that the gene technological modifications in the barley led to only minimal changes in gene activity and the composition of the plants. The differences between the two conventional wild-type strains was considerably greater than that between the transgenic and corresponding parent strain.
In addition, it was shown that the colonisation with mycorrhiza fungi greatly altered the composition of the barley plants – independently of whether the barley was transgenic or non-transgenic.
The results clearly show that classic breeding and environmental factors such as fungal infection (e.g. mycorrhisation) changed cultured plants considerably more than the targeted gene technological introduction of a single gene.
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GM barley: Unintended effects?
Conventional breeding causes more changes in plants than genetic engineering. Uwe Sonnewald discusses the research findings.