By Blake Jackson
Researchers at the University of Kentucky Martin-Gatton College of Agriculture, Food and Environment have discovered that a fungus living inside a native Kentucky woodland grass produces an unusual combination of chemicals that may help defend the plant against insects, according to Jordan Strickler, Agriculture Communications Specialist at the University of Kentucky.
The study, published in Applied and Environmental Microbiology, focused on bearded shorthusk, a wild grass commonly found in Kentucky forests. The plant hosts Epichloë brachyelytri, an endophyte that lives within the grass without causing disease.
Instead, the two organisms have a mutually beneficial relationship: the grass provides the fungus with a habitat, while the fungus produces compounds that can discourage insects from feeding on the plant.
The research team, led by Christopher Schardl, Ph.D., and Padmaja Nagabhyru, Ph.D., of the Department of Plant Pathology, identified three alkaloids produced by the fungus.
Two compounds, exo-1-acetamidopyrrolizidine and chanoclavine, are typically intermediate products that fungi use to create more complex chemicals. In this case, however, the fungus retains both compounds rather than converting them further.
“What makes it special is that it is the first fungus ever shown to do this with both chemicals at the same time,” Schardl said.
Researchers collected grass samples from six Kentucky locations spanning 171 kilometers, including the Kentucky River Palisades, Mammoth Cave National Park, Red River Gorge and Carter Caves State Resort Park. They also examined plants cultivated at The Arboretum, State Botanical Garden of Kentucky, with assistance from UK staff members Wes Hansen and Judson Collins.
Using ultrahigh-performance liquid chromatography-tandem mass spectrometry, the scientists measured the alkaloids found in leaves, seeds, and young shoots. Their results indicated that producing these compounds requires substantial energy from the fungus.
“We have intriguing evidence that in young shoots, the endophyte has an internal struggle over which chemical pathways to feed, when those pathways need the same building blocks,” Schardl said.
“That also explains why the endophyte has lost one or another of these chemicals in a few locations where we guess that insects aren’t as much of a problem and the fungus can save energy by skipping some of the chemistry.”
The researchers also traced the unusual chemical combination to different evolutionary processes, including gene exchange and hybridization among fungi. Their findings could help scientists better understand grass-fungus relationships and potentially support the development of safer pasture grasses for livestock.
“Finding it more often than expected by chance motivated us to investigate if this chemical blend is an especially potent protectant from insects,” Schardl said.
Photo Credit: martin-gatton-cafe
Categories: Kentucky, Education