Temporal variations in isolation frequency of endophytic fungi of Japanese beech.
To determine the dominant fungal endophytes of Japanese beech (Fagus crenata) and to monitor their isolation frequency, fungi were isolated from symptomless organs of beech including leaves, petioles and current and old (1- to 5-year-old) twigs after surface sterilization. Of the 13 fungal taxa obtained, 3 were isolated most often. An unidentified species of Discula and an unidentified sterile fungus, Lb, were isolated most frequently from leaves, and an unidentified species of Phomopsis was isolated most frequently from twigs. The isolation frequency over the growing season varied for the 2 dominant fungal species in the leaves, Discula sp. and Lb. These 2 species had similar patterns of isolation, even in petioles and current-year twigs, although isolation frequencies of a given species varied with organs. An organ-specific distribution of the fungal species in the host plant was apparent. The 3 fungal species noted above were considered to be the dominant endophytes of the Japanese beech.