Re-thinking the free radical

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Re-thinking the free radical

http://masseynews.massey.ac.nz/2006/Press_Releases/03-08-06b.html

Massey News - New Zealand

They have a reputation as damaging chemicals to be fought with anti-

oxidants, but free radicals are naturally-produced by microbes,

plants, and animals for good reasons.

Dr Aiko Tanaka, a molecular geneticist under the supervision of

Professor Barry in the Institute of Molecular BioSciences, has

found that free radicals play a key role in maintaining symbiotic

relationships between microbes and plants.

An inevitable by-product of aerobic respiration, free radicals help

to protect host organisms from pathogens. In animals the deliberate

production of oxygen radicals by the immune system allows the host

to destroy invading bacterial pathogens. This is an important

natural mechanism for controlling disease in humans.

Professor says plants also produce free radicals to kill

invading bacterial and fungal pathogens. This role in defence

mechanisms is well understood but Professor 's latest research

reveals a surprising new function.

The researchers studied a mutually beneficial relationship between a

fungal endophyte and perennial ryegrass. Dr Tanaka and Professor

`switched off' a gene in the endophyte responsible for the

production of free radicals and found that the fungus then grew

unregulated, eventually taking over and killing the ryegrass.

Professor says further research revealed that the production

of free radicals by the fungus is triggered by communication, known

as molecular signalling, from the ryegrass host. The primary purpose

of the signalling is to control the growth of the fungus and

maintain a symbiotic relationship.

The results of this research will be published in the leading plant

science journal The Plant Cell and can be read online at:

www.plantcell.org. Professor will present these research

findings later this year at a Gordon conference in New Hampshire,

USA.

Created: 8 March, 2006