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A RARE fungus discovered in Western Australia could one day control
some of the common diseases and pests that attack crops. The sterile red
fungus – so-called because it produces no fruiting bodies or spores – establishes
itself inside the roots of a plant. It then appears to both protect and
stimulate the growth of its host.

Å®ÉúСÊÓƵs from the University of Western Australia in Perth discovered
the sterile red fungus in late 1987. They have been carrying out research
and field trials since 1988, together with colleagues from Biotech International,
a company in Perth. The results of the trials are now emerging.

So far, the researchers have tested the sterile red fungus on about
40 species of plant – ranging from cereal crops such as wheat to species
that are native to Australia, such as eucalyptus. The fungus makes plants
grow faster and increases the yield of crops by up to 40 per cent.

In each species, the fungus appears to prevent damaging diseases, such
as fungal infections that rot the plants’ roots. Such diseases are the most
significant cause of lost cereal crops in Western Australia, and there are
many areas in Australia where the risk of root-rotting disease is so high
that farmers have no choice but to avoid growing cereal crops completely.

Peter Keating, Biotech International’s director of research and development,
says that the fungus secretes a protein that appears to have an antibiotic
effect against other fungi. At the same time, it secretes another chemical
that stimulates the growth of roots. ‘There is a principle in microbiology:
first in, best dressed,’ says Keating. ‘So if there is a beneficial fungus
living in the roots of a plant, pathogenic (disease-causing) fungi can’t
get in.’

The fungus has another intriguing property that makes it unique, says
Keating. It appears to infect every type of plant the researchers have tested
it on. Usually, fungi that interact with plants are specific to a particular
group of plants.

The researchers have used a culture of the sterile red fungus in the
laboratory to treat native plants at the micropropagation stage. They applied
the culture directly to crop seeds such as wheat. Field trials also took
place in various areas of Western Australia towards the end of last year.
According to Keating, the trials demonstrated that the growth seen in the
laboratory can also be achieved in the field.

On the strength of the trials, the researchers have won the cooperation
of most state agriculture departments in Australia, and larger-scale field
trials will be carried out in 1990. ‘We expect that by 1991, we’ll be producing
the fungus for the wheat industry and for horticultural applications,’ says
Keating.

The prospect of genetically engineering sterile red fungus has excited
researchers. It could be manipulated to produce tailor-made secretions within
a host plant – resulting in what the team calls ‘indirect genetic engineering
of plants’.

It might be possible, for example, to make the fungus produce a protein
secretion similar to BT Toxin – a chemical which controls budworm and which
is sprayed seasonally on spruce forests in Canada. The host plant of the
fungus would then find itself in possession of a lifelong supply of ‘natural
¾±²Ô²õ±ð³¦³Ù¾±³¦¾±»å±ð’.

This sort of insecticide might protect a plant against a particular
pest or even a class of pests. Some agricultural pesticides could be rendered
obsolete.

Already, the Australian government has provided A$650,000 (Pounds sterling
325,000) for the work, the largest research grant ever received by the university.

There is also some evidence, which has yet to be confirmed, that the
sterile red fungus can fix small amounts of nitrogen from the air. Biologists
believed that only some bacteria and blue-green algae can do this. If the
fungus does indeed fix nitrogen, then this mechanism could be enhanced by
genetic manipulation. A plant infected with such a modified fungus would
possess a built-in source of fertiliser.

Keating believes that genetically engineered varieties of the sterile
red fungus are likely to be environmentally safe. The sterility of the fungus
prevents it from forming spores. The researchers are still puzzled about
how the fungus manages to propagate in the wild. They suspect that it is
a natural mutant of another fungus, so far unidentified. At the moment,
they are attempting to build its ‘genetic profile’, so that they can identify
it by its DNA rather than by its appearance.