EpichloëNeotyphodium

Epichloë and Neotyphodium endophytes are a group of fungal symbionts that inhabit grasses in the Poaceae family. The term often covers both sexual Epichloë species and the asexual lineages formerly treated as Neotyphodium; recent taxonomy generally treats these as Epichloë species with diverse reproductive modes. These fungi live primarily in the intercellular spaces of above-ground plant tissues and are usually transmitted through seeds, enabling widespread and persistent associations within host populations.

Most Epichloë endophytes form mutualistic relationships with their grasses. They can enhance host performance by increasing drought tolerance, growth, and resistance to certain herbivores and pathogens. A key feature is the production of a range of alkaloids, which deter insect herbivores and reduce damage from some pests. However, several of these alkaloids can be toxic to grazing animals, creating a balance between improved plant fitness and livestock safety.

In some species, the fungus can produce stromata, specialized structures on developing inflorescences, a phenomenon known as choking or infectious flowering. This can inhibit seed set and alter the reproductive biology of the host. The diversity of Epichloë endophytes includes many host-specific lineages and hybrids, contributing to a wide range of ecological interactions across grasslands and pastures.

Agricultural relevance is significant: endophyte-infected grasses are used to improve persistence and pest resistance in forage and turf systems, but management must consider animal health risks. Breeding programs often select endophyte-grass combinations that preserve benefits while minimizing toxicoses, including the use of non-toxic or low-toxin endophyte strains.