Accumulation of Alkaloids in Different Tall Fescue KY31 Clones Harboring the Common Toxic Epichloe coenophiala Endophyte under Field Conditions

Tall fescue (Lolium arundinaceum) is a highly adaptable forage, pasture and turf grass that is grown on over 14 M ha in the eastern half of the United States and in other temperate regions of the world. A significant factor in adaptability, productivity and stand persistence is in part due to the presence of an intercellular, seed-transmissible, endophytic fungus, Epichloe coenophiala. Epichloe endophytes have been shown to produce a number of alkaloid compounds only in planta, some that are beneficial in repelling insects, while others are toxic to animals. The goal of this work was to monitor the level of the ergot and loline (classified as pyrrolizidine) alkaloid accumulation in individual plants to determine the plant genotype contribution to alkaloid concentrations. The experimental design consisted of sixteen tall fescue KY31 clones in a space-planted, replicated trial over three years. Our results demonstrated that while changes in the alkaloid concentrations for each plant/endophyte genotype were observed over the three years, the overall alkaloid levels remained relatively constant when compared to other plant/endophyte genotypes combinations in the field. Additionally, overall levels of the ergot and loline alkaloid accumulation did not vary in the same way over the three years. Since the E. coenophiala endophyte genotype was the same across all clones, our results indicate that it is the plant genotype that is responsible for determining alkaloid levels in each plant, and suggest that the signal(s) from the plant to the endophyte may not be the same for ergot and loline alkaloid production.