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"In the United States, food-grade corn is tested at the grain
elevators for mycotoxins, including fumonisin," said Martin Bohn,
maize breeder and geneticist at the University of Illinois. "If the
mycotoxin is present at an unsafe level, the corn is not sold for
human food consumption. But, in cultures that consume large
quantities of corn in their diet and are in countries that do not
test for the presence of fumonisin, there have been higher cases
reported of embryo abortions and deformities in newborns."
Fusarium ear and kernel rot is primarily a problem in
drought-stricken areas with high humidity. "Farmers in parts of
North Carolina, California and other coastal areas have been forced
to take a loss and sell their entire crop for animal feed instead of
getting the premium prices for human food when the grain is tested
at the elevator and high levels of fumonisin are found," said Don
White, U of I plant pathologist.
Bohn was a member of a team in Germany studying the resistance of
corn cultivars to the European corn borer. They believe that corn
borer larvae feed on the corn, injuring the stalks and ears,
creating an opening for fungi to develop and rotting to occur. The
team also investigated the association between resistant corn
varieties and the presence of fumonisin.
The study evaluated genetically modified Bt corn for its
resistance to the European corn borer. "The study showed that
although insect management did not reduce contamination by some
fungi diseases, using Bt corn did reduce mycotoxins produced from
Fusarium rot," Bohn said. "We believe that at least a short-term
solution is to plant corn carrying the Bt gene in order to increase
the resistance to European corn borer and, in so doing, reduce the
incidence of ear rot and the concentration of fumonisin."
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White believes that the corn borer is just one of the
injury-causing elements that can give fumonisin an opening to take
hold in corn. High levels of fumonisin can be found in corn grain
with little or no evidence of insect damage or kernel rot. He has a
collection of 1,500 inbred lines that have been screened for
resistance to Fusarium ear rot and the production of fumonisin. He
has already narrowed the search to four or five highly resistant
inbreds and knows where the resistance is located in the molecular
makeup of two inbreds. "If we had funding, we could have a
commercial hybrid available in a few years," he said. "Without it,
the process will take a decade."
"It's a big problem, especially for people in Latin American
countries like Guatemala for whom corn is a major part of their diet
and the food systems may not be regulated as closely as they are in
the U.S.," said Bohn.
White hopes that genes for resistance can be added to locally
grown varieties that will replace the currently used local
varieties. "The technology exists to develop resistant varieties,"
said White. "We just need the funding to keep the research moving
forward."
Corn contaminated by fumonisin even at very low levels can be
deadly to horses and cause some diseases in pigs, but it can be sold
to use safely in cattle feed.
Bohn's research was supported by grants from the German Federal
Ministry of Education and Research, Monsanto, and Syngenta Seeds.
The study is scheduled for publication in the January 2005 journal
of the American Society of Agronomy.
[University
of Illinois news release]
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