Safety research on genetically modified barley

Barley: Eliminating undesired side effects

No commercial utilisation of genetically modified barley is at present expected – at least in Europe. Gene technological methods have also opened up new possibilities in the breeding of barley: this concerns primarily resistance to fungal diseases. However, how can one be certain that there will be no undesired side effects? Will the beneficial fungi that live in the roots of the plants be affected? That particularly has been the focus of two safety research projects.

In the USA gene technology has been used in barley breeding for a long while. New barley strains with economically interesting traits are being developed through the transfer of suitable genes, for example with resistance against harmful fungi or with a modified composition of components.

Barley is an important model organism in plant research. The aim is to learn about the development and the characteristics of plants through their genes and gene function.

Barley is one of the oldest crops and probably the oldest cereal grown by a man. Barley can also adapt to unfavourable growing conditions and is used today in many regions of the world.

Winter and summer barley. Protein-rich winter barley is used primarily as animal feed. Beer is brewed mainly from summer barley. It contains a lot of starch that is converted in the brewing process to alcohol and carbon dioxide. Barely is being used increasingly as a renewable raw material for producing bioethanol.

Genetically modified barley: Up to now, 78 field trials with GM-barley have been approved in the USA, 9 in the EU.
Photos: Test field of GM-barley; Giessen

Glucan degradation – Effective exploitation of raw materials for animal feed and brewing

Genes from bacteria that express the enzyme glucanase have been introduced into barley. In the barley grains this enzyme helps to break down the glucan, an important structural material of cell walls. This barley can then be fed to animals, which because of their enzyme endowment are not able to break down the long-chain glucans in the cell walls of the barley.

Chickens that are fed with barley usually show stunted growth and have "sticky" excretions. In trials using chickens it was shown that they could digest barley better if as little as 0.02% genetically modified barley corns were added.

The same approach – transfer of glucanase genes – is also used to improve the characteristics of barley for brewing. Through the transfer of a gene from the widespread soil bacterium Bacillus amyloliquefaciens barley varieties have been developed that can produce a heat-stable glucanase. The result of this is that glucans from the barley are better degraded, providing an additional raw material for the fermentation process. This also helps to reduce costs, since the bulky glucans are broken down during the fermentation by the glucanases from the barley and no longer block the filters.

Fungal resistance in barley: damaging to "bad" fungi, but also to the "good" ones?

Fungal infections, in particular fusarium fungi, are a frequent problem in cereal cultivation. Some fusarium species produce fungal toxins (mycotoxins ), which mix in with the harvest and can cause serious problems in animal feed and also in the brewing industry. Barley, however, is less susceptible than wheat, oats and even maize.

Two safety research projects are currently studying genetically modified barley with increased fungal resistance. The barley strains involved in the project were developed at Washington State University and have already been tested in the field.

Two barley strains are under investigation.

One of the strains contains a gene from a soil fungus (Trichoderma harzianum), which produces a chitinase. Chitinases break down chitin, which is also a component of fungal cell walls.
The other strain contains a gene from a soil bacterium (Bacillus amyloliquefaciens), which produces glucanase. The gene was transferred to barley to improve both its brewing qualities and its digestibility when used as fodder. But glucanase has additional fungal resistance properties - it destroys specific fungi.

One of the research projects now aims to examine whether beneficial fungi are also harmed by the production of the enzymes which break down chitin and glucan. Seventy to eighty percent of land plants form a symbiotic relationship with so-called mycorrhizal fungi which benefits both the plant and the fungi.

Another project is focused on the question of whether the formation of these two fungus-targeting enzymes in the plant has any undesired effects on the plant characteristics and components.

Barley itself produces glucanases and chitinases, but the relevant genes are activated too late in the plant's development, so they fail to offer adequate protection, allowing pests to attack early. Furthermore the chitinases are produced in too small a quantity and their effect is too unspecific. Genes for plant glucanases from barley have however already been transferred to other organisms, e.g. grapevines, to confer fungal resistance.

Barley: Eliminating undesired side effects

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