April 27, 2010

Library of Fungus Diversity

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The Cornell Plant Pathology Herbarium (CUP) is located on the eastern edge of campus in a newly renovated and temperature-controlled facility. In CUP, many rows of large, dark metal cabinets neatly organize 400,000 fungal specimens by species and genus.

Prof. Kathie Hodge, plant pathology and plant microbe biology, is director of the CUP.  She refers to these cabinets as “stacks” because the fungus “herbarium” functions like a library, storing dried and pickled specimens, photographs and watercolor paintings.  The CUP lends these resources to Cornell researchers and other mycologists from around the world to study fungi.

In addition to a large supply of practical samples, the herbarium houses many type samples. A “type” is the first documented sample of any particular genus or species; it provides the first record.  The type provides an example of the key characteristics for the species, and scientists compare the type to any subsequently discovered members of the same genus or species.

Although CUP’s holdings are extensive, from lichen collected in Cuba to fungi collected in China, Hodge pointed out that mycologists estimate that they have “only even named about five percent of fungal species.”

This miniscule percentage is partly due to fungi’s microscopic size and partly due to its ubiquity.  “It’s really hard to think of an environment where there is not fungi,” said Hodge.

Hodge and CUP Curator Robert Dirig both became interested in fungi through fascination with its natural beauty. They’ve devoted their careers to studying its ecology, and they continue to find intrigue in new discoveries on the job.

Dirig’s particular passion focuses on “lichens.” Lichens do not receive their own separate taxonomical subset because, as Dirig explained, lichens make the “lifestyle choice to be fungi that are in a relationship with a photosynthesizing partner.”

Dirig admires the unique and beautiful features of lichens.

For instance, Elvin Script lichen bears distinctive fruiting bodies that look like the fictitious handwriting of magical elves. Another, called Old Man’s Beard, forms long, unique strings for its body.

“In pristine habitats, they tend to be very spectacular,” explained Dirig.  However, many fungi, especially lichens, cannot survive in polluted environments. Old Man’s Beard is one of thirty lichen species now extinct in New York.

The herbarium strives to connect other fungal species to ecological changes. With a three-year grant from the National Science Foundation, CUP will soon begin to database the 109,000 local specimens that Cornell botanist, George Francis Atkinson, collected more than a century ago.

Hodge expects the cataloging project to give mycologists an image of local biodiversity in 1900.  More over, she expects that it will reveal the entrance of invasive species into the area in the past century.

For instance, according to Dirig, the university originally planted a population of American elm tress in 1865.  The trees dominated “all up and down the avenues in the university” until an invasive species entered the area. The fungus, responsible for Dutch Elm’s Disease, wiped out the American elm tree population.

The herbarium preserves fungicide-infested organisms in, as Dirig calls, “Snape’s Cabinet,” a reference to the potions closet of the Hogwarts brew-master.

The deformed tomatoes and potatoes floating in jars of formaldehyde are “relics of a former age,” said Hodge. Scientists, including mycologists, stopped using toxic chemicals, like formaldehyde, in preservation in the past century.

Deformed organisms compose Hodge’s focus. She came to Cornell to write a thesis on a group of fungi that attack insects.

“The fungus gets into the bug, takes the bug over, and when the bug dies, the fungus grows out of it like crazy hair,” Hodge said. She admitted, while these insect pathogens appear creepy and weird, she is strangely attracted to them, just as the general public is often drawn to scientific oddities.

According to Hodge, whether identifying new species of fungi or sifting through existing collections, mycologists have a great deal of work to complete.

Hodge and Dirig agree – they find their jobs rewarding.

“It’s an adventure working in a place like [CUP] because it’s got so many treasures,” Dirig explained.

Original Author: Jing Jin