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Monday, June 28, 2010 @ 1:53 AM

Microbiological problems with GM wheat

The specific microbes that could affect the growth and produce of GM wheat is yet to be found. As most of the Genetically Modified food are after all resistance to disease and contamination.

But those that could possibly be linked to wheat, this is it:
(Research data are taken from GMO Compass website: http://www.gmo-compass.org/eng/grocery_shopping/crops/22.genetically_modified_wheat.html)

Poisonous Fusarium infestations: New solutions with genetic engineering?

Septoria, Fusarium, and common bunt are fungal diseases that often cause problems for wheat growers. These fungal diseases can spread rapidly when conditions are mild and moist.

One disease that poses particularly serious problems is Fusarium. Infected ears will either fail to produce grains or will produce grains that are small and stunted. Problems with Fusarium, however, don’t end there. A crop affected by Fusarium infection can also contain dangerous substances that can impact the health of humans and livestock.

Certain strains of Fusarium produce mycotoxins. Mycotoxins is a general term for poisonous compounds produced by fungi, which are thought to protect germinating spores from microbial infection. Mycotoxins remain in food during processing and can lead to chronic and acute diseases. In high concentrations, they can cause nausea and vomiting. Certain Fusarium toxins are implicated in cancer and have been known to affect hormonal balances.

Right now, there is no efficient way of stopping Fusarium infection. Although management strategies using resistant cultivars, crop rotation, and chemical fungicides are helpful, they are still not enough to stop the disease when conditions are conducive to infection. Fusarium is responsible for yield losses and mycotoxin contamination in wheat grown around the world.

Genetic engineering opens the door to new strategies for managing Fusarium and other fungal diseases. Scientists are currently developing genetic approaches to conferring resistance to fungal diseases and are testing their effectiveness on wheat. Field trials are underway in many countries, including countries in Europe, to find out if experimental GM wheat plants are actually resistant to fungal infection and thereby produce grains won’t be laden with dangerous mycotoxins.

GM wheat has resistance against pathogens

• fungal resistance, in particular against infections with fusarium or mildew. Infestation of plants with these fungi can lead to contamination of the wheat products with strong toxins ( mycotoxins). Resistance against smut fungi (Ustilaginomycetes; loose smut, stinking smut).
Fungal Resistance

Fungi are responsible for causing many plant diseases. Genetic engineering is being used to create fungus resistant crops.
For some plant species (potatoes, maize, cereals, grapes) fungal infestations - e.g. blight, grey mould, or Phytophthora - can lead to significant yield losses.

Fungal diseases are usually combatted with chemical fungicides or heavy metal compounds (e.g. copper vitriol). For some crops, fungus resistant cultivars have been developed using conventional breeding methods.
Intensive work is underway to develop transgenic plants with acquired fungal resistance. So far, none of these efforts have resulted in commercially viable varieties.

Several approaches are under investigation:
• Transfering bacterial genes encoding anti-fungal enzymes, e.g. chitinase or glucanase.
• Transferring genes for anti-fungal substances already produced by some plants.
• Augmenting the hypersensitive reaction: Many plants cause individual, infected plant cells to die at the site of fungal infection, effectively stopping the infection in its tracks. This mechanism can be recruitred or enhanced by genetic engineering.

Virus resistance

Viruses cause many plant diseases and are often responsible for extensive crop losses. This makes virus resistance an important goal for crop improvement.
Although chemicals can be used to manage most plant pest and diseases, there are no practical ways of eliminating plant viral infections. In some cases, pesticides can be use to manage insects that spread viruses. Virus resistant varieties of some plants have been developed by conventional breeding techniques.
Various strategies can be used to achieve virus resistance with the aid of genetic engineering:
• Viruses are enclosed by a protein coat composed of what are known as capsid proteins. If a plant is genetically transformed with a virus' capsid protein, it can be made resistant to the respective virus. All virus resistant plants commercially grown today are based on this concept.
• Other concepts target cell to cell virus movement or virus reproduction.
• Genes taken from plants that are known to produce antiviral proteins may be transferred to crops.

Glucanase

Enzymes that break down glucanase
Glucans are important structural compounds in the cell walls of plants and fungi. Chemically, glucans are a type of carbohydrate. They consist of the same basic building blocks (monosaccharides) as starches, but the units are arranged differently.

Many microorganisms produce glucanases, which enable them to digest glucans and use them as a source of nutrients. Industrially, bacteria are used to produce glucanases on a large scale for use in applications such as beer brewing. Glucanase supplements help beer yeasts break down glucans in barley, which can often block filters. (In Germany, glucanase additives are not permitted because they do not conform to the German Beer Purity Act.)

Genes for certain glucanases (usually b-1,3-glucanases) have been transferred to plants to enable them to degrade the glucans in disease-causing fungi. Researchers are developing grapes, wheat, and barley with glucanase-conferred fungus resistance.
Genetically modified barley with a novel gene for glucanase can help improve the quality of animal feed. Some animals lack the glucanases needed to break down long chain glucanes present in barley cell walls. Therefore, poultry raised with barley without added glucanase remain small.

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