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Researchers, Unique Facility Fight Toxin in Peanuts

Researchers at the Georgia Envirotron in Griffin, Ga., say the unique facility is helping them fight a costly foe of the peanut industry.

Aflatoxin is one of a group of extremely poisonous natural mycotoxins produced by two common fungi, Aspergillus flavus and A. parasiticus.

A Costly Problem

"It's one of the most expensive problems the peanut industry faces," said Keith Ingram, chair of the Georgia Envirotron committee. Ingram is an associate professor with the University of Georgia College of Agricultural and Environmental Sciences.

U.S. peanut products don't contain aflatoxin, a natural carcinogen with tight regulatory limits here and abroad. But the industry figures it costs about $1 billion a year to keep it out, Ingram said. Georgia produces 37 percent of U.S. peanuts.

"Very few peanut seeds contain aflatoxin. But it doesn't take many seeds to cause major health and economic impacts," he said. "If a farmer's load is rejected because of aflatoxin contamination, he can still sell the crop for peanut oil, as aflatoxin can be removed from oil. But oil is a product of much lower value."

Farmers can't even sell the hulls from rejected peanuts for animals' bedding, Ingram said, due to the risk of the animals' eating the hulls.

"Aflatoxin restricts trade, too, which also affects the value of peanuts," he said. "Many countries can't export peanuts because of aflatoxin."

Searching for Resistance

Researchers have found that drought-resistant peanut varieties and varieties with long root systems tend to also be aflatoxin-resistant. Ingram and U.S. Department of Agriculture research geneticist Corley Holbrook are working to identify peanut germ plasm with these qualities.

"We've identified peanut germ plasm lines with lower incidences of aflatoxin and tested them in field conditions at the UGA Coastal Plain Experiment Station in Tifton, Ga.," Holbrook said. "We are now conducting research at the Georgia Envirotron to gather root data."

The envirotron, a $1.26 million facility, allows researchers to study how a number of stresses affect plants.

Using the envirotron's facilities, scientists can control temperature, humidity, light, pollutants and atmospheric gases. Indoor growth chambers can be used to study plants, pests and diseases, while greenhouses allow researchers to simulate field conditions.

Studying Peanut Plants From the Roots Up

"The growth chambers will allow us to gather reliable data on the peanut plant root growth," Holbrook said. Through observation tubes in the growth chambers, the scientists can also observe the roots and pods growing in the soil.

"Gathering root data is extremely difficult in field plots and really isn't even feasible," he said. "We tried to gather data using probes, but we weren't happy with the results."

Peanut farmers worldwide will be happy once the research team pinpoints aflatoxin-resistant germ plasm.

"Once we determine the best choices from the germ plasm, crop breeders across the globe can use this germ plasm to create new resistant peanut varieties," Holbrook said.

The team also plans to study aflatoxin's relationship to drought conditions.

"We know aflatoxin is associated with drought and other stresses," said Ingram. "We want to quantify how it reacts to different temperatures, levels of soil moisture and other environmental variables."

These conditions can all be replicated using the envirotron's growth chambers.

A Year-Round Growing Season

"The envirotron also allows us to conduct our experiments year-round," Ingram said. "We just harvested a crop in the middle of February, and we're ready to plant another crop. Georgia farmers won't plant their peanut crops until May."

Ingram says one of the strangest aspects of this research is creating poor conditions to support the toxins.

"We have to use poor management practices to weaken the pods and make them susceptible to the fungus," he said. "We also have to innoculate the plants with the fungus. This is another reason the envirotron facility is perfect for this type of research. Inside the growth chambers, we know the fungus is contained."

(Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)

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