Deletion of Ergot Alkaloid Production Genes in a Tall Fescue Endophyte-Scope L

Tall fescue cultivar Kentucky 31 (KY31) and its derivatives constitute one of the most important forage grasses in the nation. In most ofthe more than 35 million acres of tall fescue plantings in the U.S. the plants are infected with a seedbome fungal endophyte, Neotyphodium coenophialum. Episodes of livestock toxicosis, termed tall fescue toxicosis, are associated with this endophyte. Symptoms can range from loss of appetite to agalactia, low fertility, and even loss of hooves. Circumstantial evidence suggests that ergot alkaloids, particularly ergo valine, are the most important, and perhaps the only, etiological agents of tall fescue toxicosis. A definitive test of this hypothesis has never been undertaken due to difficulty purifying ergovaline. OUfaim is to embark on a genetically based test by producing endophytes in which the gene for the first step in ergot alkaloid production has been removed, introducing those endophytes into forage grasses, and preparing seeds from the resulting grass-endophyte symbiota (and controls) to use in future grazing trials. We have performed the necessary modification of a perennial ryegrass endophyte, isolate Lpl, which produces ergovaline levels comparable to those of N coenophialum, and the mutant we have generated fails to produce ergot alkaloids or the precursor clavine alkaloids. We have had initial success in generating a similar mutant of N. coenophialum. The proposed research is to complete the genetic alterations of N. coenophialum, test the effects ofthose alterations on alkaloid production, and test agronomic characteristics of tall fescue and perennial rye grass with these genetically modified endophytes. The project will culminate in the production and initial harvest of seed plots, to increase seeds to levels sufficient to plant paddocks for livestock feeding trials. Tall fescue with N. coenophialum specifically altered to eliminate ergot alkaloid production may be highly desirable for pasture and forage in the future.