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Fighting Fungi in the Field

Animals grazing in a grassy field might appear to be safe from harm, but a certain fungus could be turning their food against them.

Christopher Schardl, recipient of one of three University Research Professorships at the University of Kentucky this year, plans to investigate microscopic fungal endophytes living in tall fescue, the most common forage grass in the Bluegrass area. These endophytes, which grow within the plant tissues, help the grass by making it more robust and warding off insects and drought. Similar endophytes in most grasses are friendly to plant and animal life.

But tall fescue is an unfortunate exception—the fungus in tall fescue can prove toxic to wildlife or livestock, causing animals to gain weight slowly, have lower conception rates, and to possibly contract gangrene of the feet.

Schardl, a professor of plant pathology, plans to research ways to eliminate the genes in the fungus that cause it to produce toxins harmful to animals, thus generating a useful endophyte without undesirable traits.

"The concept is to have an endophyte with benefits but without the ability to produce the ergot alkaloids that cause the poisoning symptoms," Schardl says. "We've cloned the key gene for these alkaloids and will mutate that gene to nullify its function. We will then use the technique of genetic transformation to swap out the good gene and leave the nullified gene in its place."

The mutated endophyte can easily be put back into tall fescue plants to replace the original endophyte. Once in the plant this tiny fungus is transmitted through seed, so that plant breeders can conveniently use this endophyte in producing new grass varieties. The livestock farmer will benefit by having a hearty forage grass that is protected from insects, drought and other stresses, and is highly nutritious and nontoxic to the animals.

Jonathan Riggs