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

<p dir="ltr"><i>Epichloë </i>(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 <i>Epichloë </i>endophytes have implications for species diversity, food web structures, and fundamental ecological processes. In many managed pastoral systems, selected <i>Epichloë </i>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 <i>Epichloë </i>spp. and the widely used pasture species: perennial ryegrass and tall fescue. Selected <i>Epichloë </i>strains confer invertebrate, especially insect, pest deterrence to their plant hosts from the production of several alkaloidal secondary metabolites. Additional <i>Epichloë</i>-mediated attributes include tolerance against fungal diseases and abiotic stresses, such as those caused by drought and/or nutrient deficiencies. Strains of mutualistic <i>Epichloë </i>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.</p>