Beltsville scientists find fungus fascinating Fungi collections help as researchers seek life form's secrets

August 31, 1998|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

It practically killed off the elm tree, caused the Irish potato famine and has been labeled the world's largest living organism.

Fungus -- a life form that attacks athletes' feet and sprouts as mushrooms -- is nowhere more abundant than in the National Fungus Collections stored at Beltsville Agricultural Research Center.

The collections, put together and owned jointly by the U.S. Agricultural Research Service and the Smithsonian Institution, make up the largest storehouse of fungus in the world, serving as a repository for about 1 million specimens of mushrooms, toadstools and other organisms plucked by government and private scientists over the past century.

The biggest question perhaps is: Why collect fungus?

"Why have this collection? Why do we store fungus? You may as well ask: Why do we store a book in a library?" said David Farr, a research botanist assigned to the ARS Systematic Botany and Mycology Laboratory, where the collections are stored. "It's a source of information."

Scientists familiar with the Beltsville collections -- with specimens lent to private scientists about 150 times a year -- say it is a vital tool for studying a little-understood world that they believe includes 1.5 million species.

It was only in the past few years that DNA research led experts to conclude that fungi -- classified as a life form separate from animals and plants -- are more closely related to animals than plants.

"There's obviously a high leap between fungi and humans, but if you consider the life cycle of a fungus and that of a human it's very similar. We eat food and fungi go out and scavenge for food," said Gary Samuels, a research botanist at the Beltsville lab.

Samuels is using the collections to analyze Trichoderma, a fungus that might be used to kill soil-borne fungi such as crinipellis, which is crippling the African cacao plants used by U.S. chocolate producers.

Samuels, who has traveled the world to collect fungi, considers the collection vital for fighting fungi that eat crops and cost farmers billions of dollars.

"If I want to know what I collected in 1987 in New Zealand, I can go into the collection and look, and compare it to something I just collected yesterday," Samuels said.

Samuels said the problem with fighting fungi is they have an amazing ability to grow just about anywhere they can find moisture. "They're in all living organisms," he said.

Donald Pfister, a professor of systematic botany at Harvard University and the curator of a collection of fungi, lichen and algae at Harvard, said advances in DNA research also make the collections useful in combating organisms like the Irish potato blight of 1845-1850, which resurfaced about nine years ago in the United States in a different strain.

Pfister said extracting DNA from the fungus that caused the original potato famine in Ireland, collected over the past century by scientists around the world, is helping researchers combat the blight attacking U.S. farms. That fungus has cost at least $200 million.

"With DNA, the collection lets you study what happened 150 years ago," Pfister said. "And that helps you understand what's happening today."

The collections are stored in rows of metal filing cabinets in a third-floor section of the mycology lab, where the temperature is kept at 70 degrees, an ideal temperature for holding fungal specimens. A tour of them is like a walk through a Fungal Hall of Fame.

In one drawer lie specimens of the same strain that caused the potato famine 150 years ago. In others lie samples of the fungi that killed most elm and chestnut trees.

They are all frozen for three days before being placed in the collection, to prevent the leaves, twigs and soils that serve as hosts from being eaten by insects, Farr said.

Farr walks past these specimens and stops at a drawer filled with the dried mushroom portion of a giant fungus, an organism made up mostly of underground fibers that grow like tentacles into the earth.

This particular mushroom was plucked in 1939 by a U.S. Department of Agriculture scientist in Berkeley, Calif., Farr says.

"Now this is just the mushroom portion of the overall specimen," Farr says, holding up a sample of Armillaria, a giant fungus that grew to cover 1,500 acres -- almost 2 1/2 square miles -- south of Mount Adams in southwestern Washington state.

Scientists proclaimed the Washington Armillaria the largest living organism in the world when they measured it and released their findings in May 1992.

Fungus experts, known as mycologists, say the discovery should have come as no surprise.

Giant fungi are often found in the western United States, where large stretches of old growth forests make it easier for them to spread, Samuels said.

"If you have an undamaged area, a specimen will keep growing and growing and growing," Samuels said. "They're amazing."

Pub Date: 8/31/98

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