After Air, Light, and Water, the Next Most Important Thing Is Grass: An Introduction to the Epichloë–Grass Symbiosis

Epichloë (Clavicipitaceae) is a genus of filamentous fungal endophytes that have co-evolved with cool-season grasses with which they form perpetual, symbiotic associations. In natural ecosystems Epichloë endophytes have implications for species diversity, food web structures, and fundamental ecological processes. In many managed pastoral systems, selected Epichloë strains are regarded as necessary components of the sward as they confer bioprotective traits to their host grasses. The most agriculturally important associations are those between selected strains of asexual, vertically transmitted Epichloë spp. and the widely used pasture species: perennial ryegrass and tall fescue. Selected Epichloë strains confer invertebrate, especially insect, pest deterrence to their plant hosts from the production of several alkaloidal secondary metabolites. Additional Epichloë-mediated attributes include tolerance against fungal diseases and abiotic stresses, such as those caused by drought and/or nutrient deficiencies. Strains of mutualistic Epichloë have been developed into highly efficacious biocontrol products and are widely utilized within the Americas, Australia, and New Zealand for pasture persistence and wildlife deterrence.