Clavicipitaceae: Free-Living and Saprotrophs to Plant Endophytes

Fungi of the family Clavicipitaceae show diversity in life styles that range from free-living soil saprotrophs to biotrophic endophytes of grasses. Individual species of the family are important because they produce toxins and other secondary metabolites. Among the metabolites in this group are the ergot alkaloids, common in ergot (Claviceps purpurea). Some species are parasites of insects and have applications as insect biocontrol agents. Among the plant biotrophic species of the family are the endophytes of the genera Epichloe and Neotyphodium. These endophytes grow within tissues of grass leaves, stems, and seeds and produce metabolites that make grasses resistant to insects and other herbivores. Endophytes also increase resistance to fungal diseases and improve drought tolerance of hosts. Endophytes thus protect hosts from biological and environmental stresses and are often considered defensive mutualists of hosts. Because of the diversity in the family Clavicipitaceae, the group may be an ideal model system for work targeted at understanding the dynamics of endophytism ecology and evolution of plant biotrophy and defensive mutualism.