Submitted to: Mcgraw-Hill Yearbook of Science and Technology
Publication Type: Book / chapter
Publication Acceptance Date: 12/3/2001
Publication Date: 12/10/2001
Citation: Franzluebbers, A.J. 2001. Endophyte grasses. Mcgraw-Hill Yearbook of Science and Technology. Interpretive Summary: This article describes a summary of endophyte associations, the history of how the tall fescue endophyte was discovered, the mechanism for how the fungus spreads, the types of animal responses to consumption of endophyte-infected grass, and the broader ecological responses to endophyte associations. This article was specifically requested to describe how endophyte associations may affect soil biota and subsequent soil carbon an nitrogen. A study is described where grazed tall fescue pastures that had been experimentally designed to contain low and high endophyte levels for 8 to 15 years resulted in differences in the quantity and quality of soil organic matter. Soil organic carbon and nitrogen was greater, but potential soil microbial activity was lower under pastures with high endophyte infection. The endophyte association has ecological implications beyond that of the plant and associated grazing animals, which were the primary areas of most previous research.
Technical Abstract: An endophyte is a mutualistic association of a fungus growing within a plant. Tall fescue and perennial ryegrass are infected with the fungus, Neotyphodium; the association being widespread throughout the world. The association was discovered following the observation that two fields of what seemed to be similar tall fescue led to different responses in cattle performance and productivity. The endophytic association produces an array of alkaloid compounds within leaf tissue that elicit toxic responses from grazing animals. Experimental pastures grazed for 8 to 15 years with high endophyte infection were found to contain 2.1 Mg/ha greater soil organic carbon in the upper 15 cm of soil than similar pastures with low endophyte infection. Potential soil microbial activity, was however lower, suggesting that endophyte infection may inhibit decomposition of organic materials deposited to soil. Endophyte-infected grasses have also been shown to deter insect and microbial pests, indicating their impact beyond that of the plant and grazing animal.