TAXONOMY, LIFE-CYCLE, REPRODUCTION AND DETECTION OF ACREMONIUM ENDOPHYTES

Endophytes referable to the deuteromycete genus Acremonium section Albo-lanosa have been found to be widespread in the subfamily Pooideae of the Poaceae. Methods used to survey grasses for endophytes are described and a list of hosts infected with endophytes is presented and discussed. Endophytic mycelium is present intercellularly in leaf sheaths, stems, and seeds of grasses, Populations of Acremonium endophytes are classifiable into one of three categories (types) based on the degree to which stromata form in the grass population. It is proposed that the ability of endophytes to form stromata is determined by the capacity of endophyte strains to grow rapidly on sugars available in plants during culm elongation when stromata form on grasses. The mechanism of seed transmission of endophytes is described and evaluated. The mating system of Epichloe and involvement of the symbiotic fly Phorbia phrenione in vectoring conidia is also discussed. Several commonly encountered Acremonium species are described and discussed.