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Grains have a built-in defence mechanism against fungal infections

Researchers from Aarhus University have identified a gene in wheat and barley that can protect the cereals against attacks from the fungi Fusarium and Aspergillus.

[Translate to English:] Svampesygdomme fører til store tab i både mark og lager, så det er vigtigt at finde effektive værktøjer til at bekæmpe dem. Foto: Janne Hansen

Farmers have a few aces up their sleeves to prevent fungal disease infections in cereals. These measures include application of fungicides, crop rotation, and growing of cereals that are resistant to the fungi.   

Researchers from Aarhus University have now discovered a new defence mechanism in barley and wheat that might be added to the arsenal against fungal diseases: a gene that codes for a certain protein. 

Professor Henrik Brinch-Pedersen and his research group from the Department of Molecular Biology and Genetics at Aarhus University were actually not on the lookout for a gene against fungal diseases, but were working on using genetic traits in wheat that can improve the utilisation of phosphorous and other minerals in cereals.

Read the article Unique wheat passes the test.

- We found the specific genes that are important for phytase activity in cereals. In addition, we found a mutant in which the genes for phytase are more strongly expressed than in regular cereals, which gave a higher phytase activity, says Henrik Brinch-Pedersen.

Enzyme opens doors to nutrients

Phytase is an enzyme that opens the door to essential minerals that are tucked away in food and feed. Minerals such as phosphorous are often locked away in a chemical bond with phytate. The enzyme phytase unlocks this phytate bond and makes the minerals more accessible.

The fungus Fusarium also has phytase activity. When the fungus attacks a plant, it uses its own phytase to make the plant’s nutrients accessible and use them for its own growth. This phytase activity is essential for the fungus’ ability to establish itself in the plant.

- We speculated if the cereal plant contained something that inhibits the fungi’s phytase activity so it can protect itself against infections from Fusarium and Aspergillus, says Henrik Brinch-Pedersen. We found that barley and wheat contain an enzyme that breaks down protein, i.e. a protease, called HvNEP-1. Not only that, we also succeeded in identifying the gene that codes for HvNEP-1.

- When plant cells in barley and wheat are attacked, their pH decreases. It is not until then that HvNEP-1 becomes active and inhibits the phytase activity of the fungus, explains Henrik Brinch-Pedersen. Laboratory and greenhouse trials have shown that barley containing the HvNEP-1 gene is significantly better protected against Fusarium and Aspergillus. The enzyme inhibits fungal growth and completely stops the creation of fungal toxins. 

From research to real life

It is one thing to discover a gene. Another thing is whether the gene can be used efficiently in real life plant protection against fungi. Future studies will therefore show if HvNEP-1 also acts against other fungal toxins than Fusarium and Aspergillus, whether the gene is found in other crops, and how great the natural variation of the gene’s occurrence is with regard to realising its breeding potential. 

- Fungal diseases lead to great losses in the field and in storage so it is important to find efficient tools to protect against them – and the solutions need to be ones that do not lead to development of resistance to the fungi, says Henrik Brinch-Pedersen. 

For more information please contact: Professor Henrik Brinch-Pedersen, Department of Molecular Biology and Genetics, email: hbp@mbg.au.dk, telephone: +45 8715 8268