Systematics, distribution, and host specificity of grass endophytes.

Clavicipitaceous endophytes (Ascomycetes) are distributed worldwide in many grasses and sedges forming a perennial and often mutualistic association with their hosts. Most endophytes appear to produce alkaloid toxins in infected plants. The high frequency of infection in many grasses and in certain grassland communities may indicate a selective advantage of infected over non-infected host plants due to their toxic effects on grazing animals and insects. Field observations and artificial inoculations of seedlings have demonstrated a high degree of specificity of most endophytes to their host plant, particularly in asexual, seed-borne endophytes. Specific isozyme genotypes found on several host species suggest that host-specific physiological races may occur. Knowledge of host range and host specificity is vital for potential applications of endophytes in pest control.