VARIATION IN THE ABILITY OF ACREMONIUM ENDOPHYTES OF LOLIUM-PERENNE, FESTUCA-ARUNDINACEA AND F-PRATENSIS TO FORM COMPATIBLE ASSOCIATIONS IN THE 3 GRASSES

The ability of representative isolates of six recognized taxonomic groups (TGs) of Acremonium endophytes from perennial rye-grass, tall fescue and meadow fescue to form compatible associations following inoculation of seedlings of the three grasses was examined. The six TGs were not specific to their natural hosts and most representative isolates formed associations with all three host species, Incompatibility resulting in hyphal death was noted in A. coenophialum-perennial rye-grass associations. Incompatibility affecting host tissue, resulting in stunted tillers with necrosis in the region of the apical meristem, was present in associations of tall fescue with either A. uncinatum or LpTG-2 (Lolium perenne TG-2). Some associations were unstable with endophyte-free tillers being produced as plants developed. This instability was not confined to endophyte-grass associations showing either of the two types of histological incompatibility reactions. The compatibility of endophyte-grass associations was not related to the percentage of successfully inoculated seedlings obtained. This study provides further evidence that the association between Acremonium endophytes and their host grasses is complex.