ISOZYME RELATIONSHIPS OF ACREMONIUM ENDOPHYTES FROM 12 FESTUCA SPECIES

The relationships of 159 isolates of Acremonium endophytes from twelve Festuca host species, representing five subgenera, were investigated using starch gel electrophoresis of 11 enzymes. Cluster analysis of is ozyme genotypes identified six distinct groupings with genetic identit ies (I) of 0.5 or less among groupings. Three groupings were previousl y described taxa associated with a single Festuca host species, A. coe nophialum from F. arundinacea, A. uncinatum from F. pratensis, and A. starrii from F. obtusa. On F. arundinacea a second distinct grouping ( FaTG-2) was recognized. All genotypes associated with species of fine fescue (subgenus Festuca) or with F. gigantea and F. pulchella formed another distinct grouping with identical or very similar genotypes. Th e endophyte from F. altissima appeared to be most divergent from all o ther isolates studied and may represent a separate species. Most of th e gene diversity within the total isolate sample was due to differenti ation among subgroups from different hosts (H(T) = 0.484; G(ST) = 0.80 1). In addition, morphological and cultural characteristics of represe ntative isolates from each host were studied and found to be distincti ve for all major isozyme groupings. The possibility of coevolution of endophytes along host subgenera of Festuca is discussed based on genet ic relationships of endophytes and subgeneric classification of their hosts.