Mycorrhizal fungus Coprinellus disseminatus influences seed germination of the terrestrial orchid Cremastra appendiculata (D. Don) Makino

Symbiotic fungi are required to provide nutrients for orchid seed germination and seedling development, underpinning the long-term conservation and reintroduction of species. Cremastra appendiculata is a terrestrial orchid whose asymbiotic seed germination has been studied to some extent, but the role of symbiotic fungi in seed germination is still unclear. We isolated a number of strains of mycorrhizal fungi from the roots of C. appendiculata and used them for in vitro experiments to investigate the role of mycorrhizal fungi in seed germination and seedling establishment. Molecular analysis showed that the seven isolated strains belonged to the genera Candida (DJF-01), Mucor (DJF-06), Coprinellus (DJF-10), Gongronella (DJF-11), Barnettozyma (DJF-13), Penicillium (DJF-15), and Trichoderma (DJF-17). The isolated strain Coprinellus disseminatus DJF-10 was chosen for further experiments because it formed pelotons inside protocorms and promoted seed germination (up to 71.61 ± 0.92% seeds germinated) after 30 days co-cultivation; moreover, some protocorms grew up to seedlings with one leaf and roots after about 6 months. This is the first report that C. disseminatus can promote seed germination and seedling development of C. appendiculata; these findings provide new knowledge to support species conservation.