Accumulation of alkaloids in different tall fescue KY31 clones harboring the common toxic Epichloë coenophiala endophyte under field conditions

Authors: Dinkins, Randy; Coe, Brenda; PHILLIPS, TIMOTHY - UNIVERSITY OF KENTUCKY; JI, HUIHUA - UNIVERSITY OF KENTUCKY

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2023
Publication Date: 1/26/2023
Citation: Dinkins, R.D., Coe, B.L., Phillips, T.D., Ji, H. 2023. Accumulation of alkaloids in different tall fescue KY31 clones harboring the common toxic Epichloë coenophiala endophyte under field conditions. Agronomy. 13(2). Article 356. https://doi.org/10.3390/agronomy13020356.
DOI: https://doi.org/10.3390/agronomy13020356

Interpretive Summary: Tall fescue is a highly adaptable forage, pasture and turf grass that is grown in 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 under stress conditions is in part due to the presence of an intercellular seed-transmissible endophytic fungus Epichloë coenophiala. Epichloë endophytes have been shown to produce a number of alkaloid compounds only in planta, some which are beneficial in repelling insects, while others are toxic to animals resulting in production losses for animal producers. The goal of this work was to monitor the level of the ergot and loline alkaloid accumulation in individual plants to determine the plant genotype contribution to alkaloid levels. The experimental design consisted of sixteen tall fescue Kentucky 31 plants harboring the common toxic endophyte in a space planted replicated trial over the course of three years. Our results demonstrated that while changes in the alkaloid concentrations were observed over the three years due to differences in yearly weather conditions, the overall relative plant/endophyte combination levels tended to remain the same relative to other plant/endophyte combinations in the field over the course of the study. Additionally, we observed that overall levels of the ergot and loline alkaloid accumulation did not vary in the same manner over the three years. Since the E. coenophiala endophyte was the same genotype in all the clones, these results indicate that it is the plant genetics that is responsible for determining the levels of the different alkaloids, and suggests that the signal(s) from the plant to the endophyte may not be the same for ergot and loline alkaloid production. Future work is needed to identify these signals and how the plant and fungus communicate to produce the different alkaloid compounds that aid in the fitness of this grass.

Technical Abstract: 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, Epichloë coenophiala. Epichloë 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 alkaloid accumulation in individual plants to determine the plant genotype contribution to alkaloid concentrations. The experimental de-sign 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 re-mained 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 determin-ing alkaloid levels in each plant, and suggests that the signal(s) from the plant to the endophyte may not be the same for ergot and loline alkaloid production.