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Plant pathologist Peter Cotty (left) examines
cotton in an Arizona research field with University of Arizona graduate student
Alejandro Ortega-Beltran. Click the image for more information about
it.
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Friendly Fungus Helps Keep Aflatoxin Out of
Cotton
By Linda Tokarz
August 13, 2007 In a brutal battle for food and
space, two fungal cousins are currently duking it out across the nation's
cotton fields. Thanks to biological control strategies developed by the
Agricultural Research Service (ARS), the
better of these two microscopic relatives is winning.
Plant pathologist
Peter
Cotty, who is part of the
ARS
Food and Feed Safety Research Unit at New Orleans, La., but is located at
the University of Arizona-Tucson,
instigated this competition. By pitting a benign strain of Aspergillus
against its noxious kin, he's helping rid U.S. cotton of a harmful and costly
toxin.
While invisible and odorless, the Aspergillus fungi that Cotty is
focused on can churn out potent poisons called alfatoxins. These carcinogenic
compoundslinked to impaired growth, cancer and deathwould threaten
human health if stringent food safety standards, set by the
U.S. Food and Drug Administration, weren't in
place to screen out contaminated products.
When cottonseed becomes infested with toxin-making fungi, it must be
discarded or severely downgraded. That's because the seed is a major feed of
dairy cows, and any toxins that might be present could transfer to the animals'
milk. Every year, aflatoxin is responsible for ruining $3 million to $8 million
worth of cottonseed in the American Southwest.
Knowing that few control options exist for farmers, Cotty set out two
decades ago to find an environmentally sound and effective solution.
Eventually, he discovered one, in the form of a benign strain of Aspergillus
flavus that, when applied correctly to cotton fields, can outgrow and
outlive its more menacing cousins.
After years of rigorous studies with the strain, which is dubbed AF36, ARS
obtained approval from the U.S. Environmental
Protection Agency in 1996 to test the new biocontrol in Arizona cotton
fields.
At that time, only 120 acres of commercial cotton were treated with AF36.
Now, more than 100,000 acres of U.S. cotton have been treated, greatly reducing
levels of harmful aflatoxins.
Read
more about the research in the August 2007 issue of Agricultural
Research magazine.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.