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A "chemical condom" is being hailed as a possible breakthrough in a war that
could eventually help wipe out Australia's invasive plants and revolutionise
agriculture, August 2005 .

Scientists at the Cooperative Research Centre (CRC) for Australian Weed
Management are working on methods that could achieve contraception in
plants.

Success in the project would see higher food production and grain exports
and reduce herbicides in agriculture and the environment.

A CRC team led by Melbourne University's Associate Professor Ed Newbigin and
the CSIRO's Dr Andrew Young and Dr Steve Swain is exploiting a phenomenon
known as self incompatibility (SI) to create a possible plant contraceptive.

SI is a biological system that prevents some plants from fertilising
themselves with their own pollen.

The team is trying to trick the plants into thinking compatible pollen is
incompatible, and rejecting it.

Professor Newbigin said the aim is to cut back the weeds' production of
fertile seed, eventually reducing their populations to the point where they
become unviable.

"This is not a magic bullet or cure-all for weeds," he said.

"It is intended to be used with other methods of control, but over time we'd
expect to reduce the weed seed bank in the soil, so that farmers will then
have to spray far less."

Scientists are looking at two approaches, one of which is the so-called
chemical condom in which a natural substance is used to stop plants from
accepting compatible pollen.

The other method works like a human vasectomy, using compounds based on
natural plant molecules to stop the transfer of the pollen's sperm to the
plant's egg cells.

Research is currently focusing on wild radish, one of the grain industry's
biggest enemies which costs growers millions of dollars every year in lost
yield and control measures.

The pest, from a family of plants known as crucifiers, is also becoming
resistant to herbicides.

Scientists are using wild radish as the initial target for proving that a
contraceptive approach works.

If they succeed, research will move to identifying similar contraceptive
substances in other invasive plants like perennial ryegrass.

Weeds CRC chief executive Rachel McFadyen said it was one of the most
important research projects undertaken by the centre in its five-year war
against invasive plants.

The benefits could eventually be counted in the hundreds of millions of
dollars, she said.

"It is a highly original solution which has substantial implications, not
just for Australia, but for world food supplies and for the environment in
general," Dr McFadyen said.

"It's the kind of research that will build the scientific reputation of this
country globally and it shows the value of getting the best brains in the
country to co-operate on a particular challenge."

[aap.com.au]

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