Fungal Endophytes of Grasses in Japan : Benefits to the Host and Problems

Abstract

Among the perennial ryegrass and tall fescue in Japan, the turf-type grasses, ecotype collections and imported grasses were found to be infected with Neotyphodium endophytes, but few commercial pasture-type grasses were infected. The occurrence of ryegrass stag-gers was limited to the beef cattles and cows which had been fed with the imported ryegrass straw. Therefore, it was strongly suggested that the ryegrass staggers occurring in Japan was caused by the imported endophyte-infected grasses. On the other hand, the endophyte-infected grasses showed feeding deterrence to insects such as bluegrass webworm and Tribolium confusum, and disease resistance to Bipolaris sorokiniana, Rhizoctonia solani, Drechslera dictyoides f. sp. perenne and so on. In Japan, Neotyphodium endophytes have been isolated from 27 species of cool-season grasses in 13 genera during the last three years, and most of them belonged to the subfamily Pooideae. Among the warm season grasses, Ephelis endophytes were detected in 15 species such as bermudagrass, Pangola-grass and paragrass. Paspalum thunbergii infected with Ephelis sp. showed feeding deterrence to a rice grass hopper, and Digitariaa decumbens (Pangola-grass) also had acquires tolerance to Japanese army worm (Pseudaletia separata) and grasshopper (Aiolopus thalassimus). However, the toxicity of the endophyte-infected grasses to animals is not known. It is important to know whether non-host plants acquired the resistance to insects and plant pathogens by artificial inoculation with fungal endophytes or not, which depends on the specificity between plant and endophyte associations. Here the compatibility and incompat-ibility between them are discussed.