MOLECULAR PHYLOGENETIC-RELATIONSHIPS OF NONPATHOGENIC GRASS MYCOSYMBIONTS AND CLAVICIPITACEOUS PLANT-PATHOGENS

Acremonium sect. Albo-lanosa (Fungi Imperfecti) includes beneficial, endophytic mycosymbionts of various grasses of the subfamily Pooideae, and also the anamorph of the grass choke pathogen, Epichloe typhina (Clavicipitaceae, Ascomycotina). These fungi are seed-disseminated, thus stably maintained for many host generations. To investigate the possibility of long-term coevolution, isolates of E. typhina and anamorphs were obtained from eight grass species, sequences of their rRNA gene internal transcribed spacers were aligned with those from other Clavicipitaceae, and cladograms were generated by maximum parsimony. The results indicated that the nonpathogenic endophytes have not necessarily coevolved with their host species and that they arose from E. typhina on multiple occasions.