Symbioses: Plant, Animal, and Microbe Interactions
Whitridge, Henry O. , Southworth, Darlene .
Partial mycoheterotrophy in Cypripedium fasciculatum.
WE studied three populations of clustered lady’s slipper orchid (Cypripedium fasciculatum) and associated mycorrhizal fungi in Southern Oregon. These orchids maintain a mycorrhizal relationship into maturity. While most fungi forming orchid mycorrhizas are saprophytes or necrotrophic parasites, some non-photosynthetic, achlorophyllous orchids are myco-heterotrophs and gain all their carbon through association with fungi that obtain carbon via ectomycorrhizal relationships with trees. By analysis of fungal DNA with PCR-RFLP and DNA sequencing, we found that C. fasciculatum associates with several fungal species, at least one of which belongs to the family Russulaceae, common ecto-mycorrhizal fungi in coniferous forests. The same fungi were also found in rhizomes of the non-photosynthetic orchid Corallorhiza. Stable isotope analysis of orchid and non-orchid tissues indicates that digestion of fungal biomass in root cells supplies C. fasciculatum with substantial proportions of its carbon and nitrogen. Although C. fasciculatum is green and presumably photosynthetic under favorable conditions, our results indicate that the species also has the ability to parasitize fungi as an intermediate between non-photosynthetic, myco-heterotrophic orchid and non-orchid lifestyles. These results elucidate the ecological connections of C. fasciculatum, and have implications for managing and conserving the species and its accompanying fungi.
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1 - Bureau of Land Management, Medford District, 3040 Biddle Rd., Medford, Oregon, 97504, US
2 - Southern Oregon University, Department of Biology, 1250 Siskiyou Blvd, Ashland, Oregon, 97520-5010, USA
Presentation Type: Poster:Posters for Topics
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM