Poison Digs Its Own Grave

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http://www.sciencedaily.com/releases/2004/12/041219154204.htm

Source: Netherlands Organization For Scientific Research

Date: 2004-12-22

Poison Digs Its Own Grave

Botrytis cinerea (grey mould) has a large arsenal of molecular pumps

at its disposal to protect it against toxic substances such as

antibiotics, plant defence compounds and fungicides. Dutch

researcher Henk-jan Schoonbeek saw how the fungus started to pump

out certain toxic substances within just 15 minutes.

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Related section: Plants & Animals

Botrytis cinerea causes rot in fruit and vegetables and is therefore

a major problem for growers in horticulture and viniculture.

Unfortunately, it is scarcely affected by natural or synthetic

protective compounds, as it uses minute protein pumps (so-called ABC

transporters) to pump these back out again.

When the fungus comes into contact with toxic substances, these

initially enter it unhindered. About 15 minutes later, an emergency

mechanism starts up and the fungus secretes the toxic substances so

that their concentration in the fungus falls below the lethal dose.

Schoonbeek studied the genes involved in the secretion of toxic

substances by ABC transporters. He discovered that the activity of

the pumps was partly controlled by the toxic substances. Upon

entering the fungus, these stimulate the fungal DNA to produce

certain proteins, which then immediately pump these substances out

of the fungus.

The researcher established that this mechanism in B. cinerea is

comparable to multiple drug resistance in humans. Multiple drug

resistance is when cells that have been treated with one type of

medicine, become resistant to a completely unrelated group of

medicines. Transport proteins also play an important role in

multiple drug resistance.

One of these ABC transporters is the protein BcatrB. This protein is

involved in defending the fungus against many different toxic

substances. For example, it is active against resveratrol, a plant

defence compound from grapevines. Therefore the fungus can easily

break through the defence lines of grape plants. Although antibiotic-

producing bacteria are used to protect plants successfully against

other pathogens, the phenazine antibiotics they contain cannot stop

B. cinerea. This is because they also activate the production of the

BcatrB protein and are therefore immediately pumped back out again.

This new information is helpful in developing new strategies to

control grey mould diseases.

The research was funded by the Netherlands Organisation for

Scientific Research.

Editor's Note: The original news release can be found here.

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This story has been adapted from a news release issued by

Netherlands Organization For Scientific Research.