Protocorms of an epiphytic orchid (Epidendrum amphistomum A. Richard) recovered in situ, and subsequent identification of associated mycorrhizal fungi using molecular markers

Abstract

Epiphytic orchids have received considerable study, yet little has been published on their germination requirements in situ involving mycorrhizal fungi. Such research has been hampered by the small, dust-like size of seeds and leafless seedlings (protocorms) which are difficult to pinpoint on natural substrates, especially those on arboreal substrates (tree limbs). We report a novel seed sowing and retrieval method, modified from one applied to terrestrial orchids, used in the acquisition of epiphytic orchid protocorms from the Florida Panther National Wildlife Refuge. Seeds from two epiphytic orchid species (Epidendrum amphistomum A. Richard, E. nocturnum Jacquin) were placed in separate nylon mesh packets secured within 35 mm plastic slide mounts, and affixed to tree bark using gutter mesh and a staple gun. To confirm that the embryos were viable, some seeds were also sown on asymbiotic media in the laboratory which subsequently germinated after 52 days incubation. Of 60 packets distributed among 18 tree limb sites, one packet – harboring seeds of E. amphistomum affixed to pop ash (Fraxinus caroliniana Mill.) on a moss substrate – harbored protocorms after 267 days. Using molecular markers, a fungus assignable to the Ceratobasidiaceae, appears to be the mycorrhizal associate of these protocorms suggesting that this fungus may be associated with the germination process in situ.