ENDOPHYTIC FUNGI IN INDIGENOUS AUSTRALASIAN GRASSES ASSOCIATED WITH TOXICITY TO LIVESTOCK

Grazing of Echinopogon spp. by livestock in Australia has caused sympt oms similar to those of perennial ryegrass staggers. We observed an en dophytic fungus in the intercellular spaces of the leaves and seeds of New Zealand and Australian specimens of Echinopogon ovatus. Culture o f surface-sterilized seeds from New Zealand specimens yielded a slow-g rowing fungus. An examination in which immunoblotting and an enzyme-li nked immunosorbent assay (ELISA) were used indicated that E. ovatus pl ants from Australia and New Zealand were infected with fungi serologic ally related to Neotyphodium lolii (the endophyte of perennial ryegras s) and other Epichloe and Neotyphodium spp. endophytic in pooid grasse s. No lolitrems (the indole-diterpenoids implicated as the causative a gents of perennial ryegrass staggers), peramine analogs, or ergot alka loids were detected in the infected specimens by high-performance liqu id chromatography or ELISA. However, in endophyte-infected E. ovatus p lants from New Zealand, analogs of the indole-diterpenoid paxilline (t hought to be a biosynthetic precursor of the lolitrems and related tre morgens) were detected by ELISA and N-formylloline was detected by gas chromatography. Endophyte-free specimens of New Zealand E. ovatus did not contain detectable paxilline analogs or lolines and were more pal atable than infected specimens to adults of the pasture pest Listronot us bonariensis (Argentine stem weevil). Hyphae similar to those of the E. ovatus endophyte were also found in herbarium specimens of Echinop ogon nutans var. major, Echinopogon intermedius, Echinopogon caespitos us, and Echinopogon cheeli. This appears to be the first time that an endophytic Neotyphodium species has been identified in grasses endemic to New Zealand or Australia.