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.”
