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Researchers develop improved test
for soybean sudden death syndrome
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[SEPT.
18, 2004]
URBANA --
Sudden death syndrome, which is
caused by the fungus Furarium solani, has emerged in recent years as
a major disease problem for soybean growers in Illinois. Despite the
increased availability of new resistant soybean varieties, the
information for growers to make decisions on which seed to plant has
been limited by the available methods of testing for this disease.
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To meet the need for better diagnosis
of SDS, researchers at the University of Illinois have recently
developed a new technique for detecting the disease that is faster
and more accurate than the methods currently in use.
"With present methods, you need to grow
a sample on a gel plate to get your results," said Terry Niblack,
nematologist in the Department of Crop Sciences at the U of I. "The
fungus grows so slowly that there is a major lag time before you can
obtain any results. With this new method, the diagnosis can be made
within one day rather than the two or three weeks for current
tests."
Major work in developing the improved
test was conducted by senior research specialist Xuebiao Gao. Field
studies were carried out by graduate student Tamra Jackson.
Additional support was provided by Glen Hartman, USDA plant
pathologist at the U of I, and Susan Li, director of the Soybean
Disease Germplasm Collection at the U of I. Primary funding for the
project came from the Illinois Soybean Checkoff Board.
The new test utilizes a molecular
technique known as real-time polymerase chain reaction. With this
technique, the results can be measured as soon as they show up in
the test rather than only after it is finished, as in other
molecular testing methods
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"That allows us to determine not only
the presence of the fungus but also the exact quantity in a sample,"
Niblack said. "Having detailed information on the amount of fungus
present is important because we are starting to have more and more
soybean varieties with resistance to SDS. The more precisely you can
characterize the disease in a field, the better you can control it."
She points out that one major problem
for growers is the fact that the fungus can be present in a field
without showing obvious symptoms.
"As part of this research, we are
working on relating the amount of the fungus in the roots to the
amount of disease that shows up," she said. "With this test, we can
tell growers how much of the fungus they have in their fields even
when there are no signs of disease. You don't necessarily have to
see symptoms for a resistant variety to pay off."
She notes that the new test should
become affordable for commercial laboratories as the prices for the
new technology come down over time.
"As SDS
becomes more of a problem around the state, it will become
increasingly important to have a fast and accurate test for
diagnosing the disease," Niblack said. "It will also have important
benefits for researchers, especially in looking at the interaction
between SDS and the presence of soybean cyst nematodes."
[University
of Illinois news release]
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