Mycorrhizal diversity of the orchid Cephalanthera longibracteata in Japan

Cephalanthera is an orchid genus that harbors mixotrophic species obtaining carbon compounds from nearby trees via ectomycorrhizal fungi. Cephalanthera species show variable levels of fungal dependency and specificity. We identified mycobionts from C. longibracteata. A total of 142 root samples were collected from 68 C. longibracteata individuals at five sites in Japan, and their associated mycobionts were identified based on the DNA sequences of nuclear ribosomal internal transcribed spacer regions using a molecular taxonomical method. Several groups of ectomycorrhizal fungi, including Russulaceae, Sebacinaceae, and Thelephoraceae were identified from the roots of C. longibracteata, suggesting that C. longibracteata has lower fungal specificity than other Cephalanthera species examined previously.