Dissertation/Thesis Abstract

Identification of Site-Specific Mycorrhizal Fungi Associates of the Federally Threatened Eastern Prairie Fringed Orchid (Platanthera leucophaea) in Illinois
by Thixton, Hana Lea, M.S., Southern Illinois University at Edwardsville, 2017, 78; 10275470
Abstract (Summary)

The eastern prairie fringed orchid (Platanthera leucophaea) (Orchidaceae) was once a common and widespread species in wet prairies, sedge meadows, bogs, and fens throughout the upper Midwestern United States. The orchid has experienced great declines over time due to habitat loss, over-collection, and competition with non-native taxa and is currently listed as a federally threatened species. It is currently listed as a U.S. federally threatened species. Conservation efforts aimed at its recovery have included habitat restoration, hand pollination to promote genetic outcrossing/increased seed set, and artificial seed sowing into suitable habitats. Despite multiple, and well-coordinated efforts, seedling establishment leading to self-sustaining populations in situ has yet to be verified. All orchids form symbiotic relationships with mycorrhizal fungi for seed germination and early seedling development. Recent research suggests that all orchid conservation efforts focus their research on understanding orchid fungal interactions. Previous research suggests that P. leucophaea depends on associations with basidiomycete fungi assignable to Ceratobasidium (formally Ceratorhiza) throughout its range. The purpose of this study is to determine if specific strains of the fungi associated with the Eastern Prairie Fringed Orchid are widespread, or if sites possess their own unique strains of fungi necessary for the successful reproduction and survival of the taxa. Identification of site-specific mycorrhizal fungi could provide a new approach for the conservation efforts of P. leucophaea and other rare orchid species in North America. Field collections of roots were made from eleven sites from late June through early July 2016. Roots collected were processed for mycorrhizal fungi and fungal DNA was isolated. ITS Primer amplification followed by DNA sequencing was used for identification of the fungal strains. Fungal isolations and culturing was successful for all 11 populations, leading up to over 50 possible candidates. Out of the 11 sites sampled, only 2 sites had successful identification of orchid mycorrhizae, the rest were identified as common soil fungi. The root from the Baldwin Marsh, Iowa contained Ceratobasidium and Helm Road, Illinois contained Tulasnella.

These fungi will germinate seeds of another orchid species, Spirnathes cernua. Seed germination experiments with these fungi and seeds of P. leucophaea have not been completed. Future germination experiments with seeds of P. leucophaea with either of these fungi will need to be done to indicate if they are used by the orchid to reproduce and would be useful for restoration efforts in the species. Why the root samples from so many sites did not contain orchid associates is not known. Our one plant root sample size was very small. We were constrained by the concerns of the fish and wild life service about the dangers of root removal from the plants. Future studies should include the sampling of more root samples from each population. This may reveal if the plants in these sites truly lack orchid fungi or if our initial sample size was too small to capture plants with the fungi.

Indexing (document details)
Advisor: Esselman, Elizabeth
Commitee: Fowler, Thomas, Williams, Jason
School: Southern Illinois University at Edwardsville
Department: Biological Sciences
School Location: United States -- Illinois
Source: MAI 56/05M(E), Masters Abstracts International
Subjects: Biology, Plant biology
Keywords: Conservation, Federally threatened species, Mycorrhizal fungi, Orchid
Publication Number: 10275470
ISBN: 978-0-355-05143-8
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