Variation in the expression of ergot alkaloids between individual tillers of perennial ryegrass

Abstract

Epichloë fungal endophytes of cool season grasses are well-known to produce a range of alkaloids of benefit to the host. Some of these compounds are advantageous to agriculture due to qualities that promote pasture persistence (e.g., the loline class of alkaloids confer insect protection) while others are detrimental to the well-being of grazing livestock. The ergot alkaloids (e.g., ergovaline), produced in ryegrass and tall fescue associations, causes poor animal health in farming regions in many countries around the world and further study is required to improve our knowledge on this class of compounds. Here we present the application of a quantitative LC-MS/MS (liquid chromatography coupled to mass spectrometry) method measuring eight ergot alkaloids (chanoclavine, agroclavine, elymoclavine, lysergol, lysergic acid, ergine, lysergyl-alanine, ergovaline) produced by endophyte infected grasses, to monitor levels in individual tillers from multiple plants of a single cultivar of perennial ryegrass (Lolium perenne cv. “Grasslands Samson”) infected with a common toxic endophyte strain (Epichloë festucae var. lolii). Monitoring the expression in individual tillers allows an estimation of the variability within a plant (between tillers) as well as between plants. The study showed that there is significant variation in the concentration of the ergot alkaloids between tillers of a single plant, at or exceeding the level of variation observed between individual plants of a population. This result emphasizes the fundamental importance of robust experimental design and sampling procedures when alkaloid expression assessment is required and these need to be rigorously tailored to the hypothesis being tested.

Occurrence of Alkaloids in Grass Seeds Symbiotic With Vertically-Transmitted Epichloë Fungal Endophytes and Its Relationship With Antioxidants

“…The alkaloid ergovaline is mainly known due to its toxicity on mammals (Bush et al, 1997;Saikkonen et al, 2013), although it can also be effective in deterring herbivorous insects (Potter et al, 2008). The concentration of the alkaloid ergovaline varies greatly among plant species, genotypes and tissues (Schardl et al, 2013;Mace et al, 2014). A great variation was previously shown between plants (0-0.47 µg.g −1 ) in stems and leaves of F. rubra (Vázquez- de-Aldana et al, 2007de-Aldana et al, , 2010.…”

“…The seed is the plant structure with the greatest fungus/plant biomass ratio which stores fungal alkaloids (TePaske et al, 1993;Justus et al, 1997;Vázquez-de-Aldana et al, 2003). The profile and concentration of alkaloids varies greatly responding to factors such as species identities, plant tissue/stage, and growth conditions (Bush et al, 1997;Faeth et al, 2002;Rasmussen et al, 2007;Mace et al, 2014). Production of alkaloids can be triggered by herbivory (Sullivan et al, 2007;Fuchs et al, 2017a), although it remains unknown whether alkaloids accumulate in seeds as a consequence (Gundel et al, 2017).…”

Activities and Effects of Ergot Alkaloids on Livestock Physiology and Production

“…Variations in ergot alkaloid type and concentration in the live plant [ 18 , 19 ] and in harvested plants [ 20 ] that are available for consumption will contribute to a varied alkaloid dose, but not necessarily account for the multiplicity of effects that have been generally attributed to ergotism in livestock. Rather, this diversity of effects is due to an interruption of a number of different biological processes by ergot alkaloids.…”

Recent investigations of ergot alkaloids incorporated into plant and/or animal systems

“…This research topic, Recent Investigations of Ergot Alkaloids Incorporated into Plant and/or Animal Systems, epitomizes that reality through diverse scientific approaches addressing the core issue of ergot alkaloids in agriculture. Innovative research articles highlight the numerous effects that ergot alkaloids can have on livestock (Aiken and Flythe, 2014 ; Duckett et al, 2014 ; Egert et al, 2014 ; Eisemann et al, 2014 ), improved characterizations of fungal endophytes (Young et al, 2014 ), clarification of the alkaloid variation within the plant (Mace et al, 2014 ), and how fungal infestations and subsequent alkaloid concentrations interact with the environment (McCulley et al, 2014 ). Furthermore, challenges such as alkaloid stability in collected samples (Lea et al, 2014 ), the generation of a large alkaloid source in the absence of a consistent supply for animal studies (Ji et al, 2014 ), a perspective on interpreting alkaloid concentrations and level of animal response (Craig et al, 2015 ), and rapid screening of livestock are addressed (Rosenkrans and Ezell, 2015 ).…”