Ex situ symbiotic seed germination, isolation and identification of effective symbiotic fungus in Cymbidium mannii (Orchidaceae)
硬叶兰种子的迁地共生萌发及有效共生真菌的分离和鉴定

Aims The in situ and ex situ seed baiting techniques, which have been developed in recent years, are effective methods to study the compatible mycorrhizal fungi of orchids. Our aim was to obtain the compatible mycorrhizal fungi of epiphytic Cymbidium mannii using the ex situ seed baiting technique. Methods Bark, moss, litter and humus around the roots of adult plants of C. mannii were collected as substrate to cultivate C. mannii seeds in the laboratory. The fungi were isolated from developed protocorms and identified by morphological and molecular characteristics. The effects of different mycorrhizal fungi and light on seed germination were examined by in vitro symbiotic germination. Important findings The isolated fungus was identified as a species of the genus Epulorhiza and was named as FCb4. After 58 days cultivation, seeds inoculated with FCb4 strain and FDaI7 strain (Tulasnella, isolated from Dendrobium aphyllum) had a high germination ratio, whereas seeds without the fungus failed to germinate. There was no significant difference between the germination ratios of seeds inoculated with FCb4 and FDaI7 strains, but FCb4 was significantly superior for seedling formation and development compared with FDaI7 in light. This indicated a lower degree of symbiotic fungal specificity on seed germination than the protocorm development stage in C. mannii. The fungus we obtained was effective for seed germination, and protocorm and seedling development for C. mannii. Germination and protocorm production were higher in the dark (0/24 h light/dark) than the light condition (12/12 h light/dark), whereas the subsequent protocorm development was better with light. These findings will aid in seedling production and reintroduction of C. mannii.