Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
3/25/02
Contacts:
Mark Gleason, Plant Pathology, (515) 294-0579, mgleason@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Yard and Garden Column for the Week Beginning March 29, 2002
Fun at the Fungal Frontier
By Mark Gleason
Extension Plant Pathologist
Iowa State University
Some people think science has already exposed all the secrets of the natural world, and there's nothing new to know. That cliché definitely doesn't apply to fungi. Except for the mushrooms on your pizza, you may not have spent much time pondering these humble, versatile organisms. But the most exciting thing about fungi is that we know almost nothing about them.
The fungi that cause plant diseases are especially shrouded in mystery. In the roughly 150 years since science first took notice of them, we have barely scratched the surface in understanding how they live.
Some of you may be yawning by now. But scientists called mycologists think the mysteries of fungi are exciting, since it means there are countless new discoveries waiting to be made. Some of these discoveries will help protect our crops from destructive diseases.
You want drama? Encounters with bizarre phenomena? Fungi can make "The X Files" seem duller than a home-shopping show.
Out on the frontiers of fungal knowledge, nothing is more thrilling than discovering a new fungus. It's the same thrill explorers feel after stumbling onto a plant or animal that nobody ever noticed before: adding a new splash of paint to the giant canvas of the known natural world. It's almost as exciting to find an "old" fungus living in new and unexpected places.
The most exciting moment of my 20-year career in plant pathology happened last year. Naturally, fungi were involved.
A Ph.D. student in my laboratory, Jean Batzer, began to take a close look at the dark-colored fungi that live on the waxy outer coat of apples. If you grow your own backyard apples, you've probably seen these critters as smudgy blotches or groups of tiny black dots when you pick apples in the fall.
These fungi, called sooty blotch and flyspeck (SBFS for short), are a major pain in the wallet for commercial apple growers, to the tune of thousands of dollars per year in pesticide sprays and loss of marketable fruit.
Jean collected 500 individual bits of SBFS fungi from nine orchards in Iowa, Missouri, Illinois and Wisconsin. She grew them on a special fungus food, called agar, in our laboratory. The SBFS fungi don't really enjoy artificial foods, so keeping them alive was a challenge.
Jean then tapped the expertise of Tom Harrington, a fungal genetics expert at ISU, to sort out her captured fungi through the magic of biotechnology. In Harrington's lab, she used polymerase chain reaction (PCR), a bit of chemical wizardry that multiplies an organism's DNA thousands of times in just a few hours.
Jean then delivered her bucketfuls of fungal DNA to ISU's DNA Sequencing Facility, where impressive-looking machines decoded the exact order of amino acids that form the DNA. Revealing this order is like scanning a blueprint to help you understand how a house is built. But Jean's blueprints were for fungi, not houses.
How do you sort through 500 blueprints? Computers helped to match up
similar amino-acid sequences, but the work wasn't done. Jean and Tom's
technician, Wei Chen, did the final matching the old-fashioned way, using
their own eyes to find the final matches.
The results were electrifying. Jean and Wei found nearly 20 new fungi
in the SBFS group, compared to only four that had been described in the
previous 80 years of research on SBFS. It turns out that SBFS fungi are
a lot more diverse than anybody had guessed.
OK, maybe "electrifying" sounds a trifle over the top. But in the small world of fungal research, finding even one fungus is better than finding a diamond. To find 20 new disease-causing fungi at once is so rare it practically never happens.
Now that the new SBFS fungi have been fingerprinted, we need to find out how they operate. The next step involves painstaking experiments to pinpoint the environmental needs of each fungus. We also need to find out where they fit in the grand scheme of fungal classification. These tasks will take years. Finally, we should have enough insights to help apple growers stop SBFS with fewer pesticide sprays.
Meanwhile, Jean is taming her exotic menagerie of captured fungi. Most people may have trouble comprehending the thrill of this pursuit. But for a mycologist, the fun factor beats the Super Bowl and the NCAA basketball final rolled into one.
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ml: isugarden
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