Infection of Tall Fescue with Acremonium coenophialum by Means of Callus Culture. Mark C. Johnson, Department of Plant Pathology, University of Kentucky, Lexington 40546. Lowell P. Bush, Department of Agronomy, and Malcolm R. Siegel, Department of Plant Pathology, University of Kentucky, Lexington 40546. Plant Dis. 70:380-382. Accepted for publication 24 October 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-380.

Calli initiated from peduncle tissue of endophyte-free tall fescue plants and maintained on a culture medium were inoculated with the endophytic fungus Acremonium coenophialum. This was accomplished by making an incision into the middle of calli 1–2 cm in diameter and inserting a small amount (< 1 mm²) of mycelium followed by a 10-wk incubation. About 17% of the regenerated plants from these calli were infected as determined by microscopic examination of leaf sheaths and by enzyme-linked immunosorbent assay. Additional evidence for the successful establishment of A. coenophialum in these plants was the accumulation of pyrrolizidine alkaloids and conferment of resistance to the oat bird cherry aphid. A. coenophialum was reisolated from leaf sheaths of the artificially inoculated plants. Inoculations of perennial ryegrass calli with Acremonium spp. resulted in only endophyte-free plants upon regeneration of callus. We were unable to induce shoot regeneration in Acremonium-inoculated bluegrass and orchardgrass calli.