Alkaloid Quantities in Endophyte-Infected Tall Fescue are Affected by the Plant-Fungus Combination and Environment.

M Helander,I Saloniemi,T Phillips,K Saikkonen,S H Faeth,L P Bush,R Mcculley

doi:10.1007/s10886-016-0667-1

Abstract

Many grass species are symbiotic with systemic, vertically-transmitted, asymptomatic Epichloë endophytic fungi. These fungi often produce alkaloids that defend the host against herbivores. We studied how environmental variables affect alkaloids in endophyte-infected tall fescue (Schedonorus phoenix) from three Northern European wild origins and the widely planted US cultivar ‘Kentucky-31’ (KY31). The plants were grown in identical common garden experiments in Finland and Kentucky for two growing seasons. Plants were left as controls (C) or given water (W), nutrient (N) or water and nutrient (WN) treatments. For 8–10 replications of each plant origin and treatment combination in both experiments, we analyzed ergot alkaloids, lysergic acid, and lolines. In Finland, tall fescue plants produced 50 % more ergot alkaloids compared to plants of the same origin and treatments in Kentucky. Origin of the plants affected the ergot alkaloid concentration at both study sites: the wild origin plants produced 2–4 times more ergot alkaloids than KY31, but the ergot alkaloid concentration of KY31 plants was the same at both locations. Overall lysergic acid content was 60 % higher in plants grown in Kentucky than in those grown in Finland. Nutrient treatments (N, WN) significantly increased ergot alkaloid concentrations in plants from Finland but not in plants from Kentucky. These results suggest that the success of KY31 in US is not due to selection for high ergot alkaloid production but rather other traits associated with the endophyte. In addition, the environmental effects causing variation in alkaloid production of grass-endophyte combinations should be taken into account when using endophyte-infected grasses agriculturally.

Highlights

Grasses (Poaceae) have invaded every continent of the globe, and cover more terrestrial area than any other group of plants
We examined how alkaloid production in wild tall fescues originating from Northern Europe, which are highly infected with Epichloë endophytes, and the widely used US cultivar KY31 depends on variable environmental conditions
Two S origin plants grown in Kentucky and one S and one KY31 origin plant grown in Finland did not produce lysergic acid

Summary

Introduction

Grasses (Poaceae) have invaded every continent of the globe, and cover more terrestrial area than any other group of plants. Instead of producing chemical compounds themselves, many pooid grasses have coevolved with vertically-transmitted, symbiotic Epichloë fungi (Saikkonen et al 2013; Schardl et al 2013) whose asexual forms formerly were referred to as Neotyphodium (Leuchtmann et al 2014). These hereditary symbioses are typically host specific. The fungi grow in intercellular spaces in the above-ground parts of grasses Epichloë endophytes in their host grasses are capable of producing four classes of alkaloids, which may provde the endophyte-grass symbiota with defenses against herbivores. We predicted that overall alkaloid production would be lower in Northern Europe than in Kentucky since in the latter environment the grasses would be exposed to higher temperatures and drought during the summers (Belesky et al 1989; McCulley et al 2014)

Methods and Materials

Results

Discussion