HOUSTON, Aug. 29, 2005 New research by biologists at Rice University, Indiana University and George Mason University reveals how some non-native fescue grass gets a leg up over competing native plants: it's passed over by plant-eating insects and animals because its leaves are laced with toxic alkaloids, thanks to a symbiotic fungus that has co-evolved with the grass.

In a 54-month study conducted at Indiana University, scientists showed that 'tall fescue,' a common variety that is infected with the symbiotic fungus Neotyphodium coenophialum, tended to choke out uninfected fescue and native plant species. Tall fescue took over test plots much more quickly when herbivores had full access.

The research appears in the Aug. 30 issue of the Proceedings of the National Academy of Science.

"The practical implications of our findings are that the more herbivores there are in an area, the more likely it will be that infected tall fescue grass will spread and suppress native plants," said co-author Jennifer Rudgers, now an assistant professor of ecology and evolutionary biology at Rice.

Fescue, which is native to the Mediterranean, covers an estimated 37 million U.S. acres. It is cultivated for grazing and is often used as turf grass on lawns, golf courses and highway rights-of-way. Ranchers do not typically cultivate tall fescue because the symbiotic fungus it carries, known as an endophyte, produces alkaloids that have negative health effects for livestock. It is estimated that 80 percent of U.S. fescue is endophyte-infected, and in some applications, like turf grass, it's the preferred variety.

Prior research on hereditary plant symbionts like the fescue endophyte have tended to look at plant-fungal pairings in isolation. Rudgers said she, post-doc advisor Keith Clay of Indiana University, and co-author Jenny Holah of George Mason University sought to get a more realistic picture of the ecological effects of symbiosis. <
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Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
29-Aug-2005

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