British scientists discover antibiotic-producing enzyme in oats

British scientists have discovered an antibiotic-producing enzyme in oats that could be used in the future to protect major cereal crops from fungal diseases such as "take-all."

The enzyme in oats, called Sad2, was discovered by researchers from the Norwich Research Park (NRP) led by Professor Anne Osbourn at the John Innes Center in Norwich.

The researchers found the enzyme helps in producing a chemical that makes the plant resistant to infections, said a press release issued by the Institute of Food Research on Monday.

Take-all is a particularly damaging fungal disease as it infects the roots of the plant and can be passed onto subsequent crops grown in the same field.

According to the researchers, Sad2 has evolved from an ancient family of enzymes that have remained unchanged over millions of years and are almost identical across the plant, fungi and animal kingdoms.

All the other enzymes in this family are involved in producing essential fats called sterols, such as cholesterol in humans, and include targets for cholesterol-lowering drugs, antifungals and herbicides. The discovery of a new member of this enzyme family with a completely different function was therefore surprising.

Many plants produce chemicals called "natural products" that are not essential to growth but have a range of important ecological functions, which can be attractants for pollinating insects or, in this case, protect the plant against diseases.

"Our aim in this work is to understand how these natural products are made and why the ability to produce particular natural products is limited to certain plant species," Osbourn was quoted as saying.

"Our data show that the Sad2 gene has evolved from the most ancient and highly conserved cytochrome P450 family by gene duplication and has then diverged from its original role in making sterols to adopt a new function producing an antimicrobial chemical called avenacin."

The research team has already identified five genes coding for different enzymes in this pathway and are currently isolating the others.

The researchers unexpectedly found that these genes were clustered together in the plant's genetic code; clusters of genes that have connected functions are often found in bacteria or fungi but are extremely rare in plants.

This is only the second gene cluster that has been identified in plants, according to Osbourn. He said if they could transfer this gene cluster from oats into other plants, it might be possible to breed cereals that are resistant to devastating crop diseases such as take-all.

The researchers said their findings also have broad significance for understanding how new metabolic pathways arise in plants, and this is an area that they are now investigating in other plant species such as rice and in the model plant Arabidopsis.

Source: Xinhua