Researchers search for aflatoxin resistant corn

By Holly Jessen | February 09, 2010
Posted March 3, 2010

After identifying a gene that allows aflatoxin contamination in corn, Texas AgriLife Research scientists are harnessing that information to create an aflatoxin-resistant line of corn.

That's good news for a lot of people - from farmers and ranchers to ethanol plant corn buyers. Mycotoxins, mostly aflatoxin, caused losses of about $13 million in Texas last year, the highest in the nation, researchers said. Of course, for ethanol plants, aflatoxin levels must be watched closely because it concentrates in the distillers grains and can be harmful for livestock.

The discovery of the gene (and one linked to drought tolerance) came out of a four-year study funded by the National Science Foundation, said researcher Mike Kolomiets, an associate professor in Texas A&M University Department of Plant Pathology and Microbiology. Now, with a $500,000 USDA grant, Kolomiets, Seth Murray, corn genetics researcher, and Tom Isakiet, plant pathologist, have started another four-year project to apply the information to corn breeding.

Kolomiets learned of the apparently alfatoxin-resistant gene studying a 13-member family of genes referred to as LOX, or lipoxygenase. By shutting down each gene one by one, researchers identified their function. When conditions are ripe for aflatoxins to form, one of the LOX genes appears to be manipulated by the pathogen, Kolomiets said. Mutating the gene to shut it down prevented that hijacking. "In every case, in every year, in every location, we were able to reduce aflatoxin fivefold," he told EPM.

While Kolomiets' research shows that if that gene were mutated and shut down, the resulting corn would be less susceptible to aflatoxin, the scientists aren't sure what side-effects might occur. "We would like to be very careful and not mess up nature too much," Kolomiets said. Instead, researchers will search for a natural gene—one that's not mutated— associated with low incidences of aflatoxins. "We have already found some preliminary data that this is possible," he said.

Although it's good news that researchers have, for the first time, identified the gene associated with aflatoxin contamination, developing new varieties will take years. During the first year of the four-year research project, the team will sequence 400 lines of corn. Once a better gene for aflatoxin-resistant corn is identified, the gene must be coded into elite germoplasm before field testing can begin. It may be six years or more before new aflatoxin-resistant varieties are released, Kolomiets reported.