Journal Article

Functional and genetic diversity of mycorrhizal fungi from single plants of <i>Caladenia formosa</i> (Orchidaceae)

Tien T. Huynh, Richard Thomson, Cassandra B. Mclean and Ann C. Lawrie

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 104, issue 4, pages 757-765
Published in print September 2009 | ISSN: 0305-7364
Published online June 2009 | e-ISSN: 1095-8290 | DOI: https://dx.doi.org/10.1093/aob/mcp153
Functional and genetic diversity of mycorrhizal fungi from single plants of Caladenia formosa (Orchidaceae)

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Mycorrhizal associations are essential to the plant kingdom. The largest flowering plant family, the Orchidaceae, relies on mycorrhizal fungi for germination, growth and survival. Evidence suggests varying degrees of fungal-host specificity based on a single fungal isolate from a single plant. This paper shows for the first time the diversity of endophytes colonizing in a single plant over consecutive years and the functional significance of this diversity.

Methods

Stem-collars of Caladenia formosa were collected in different seasons and years. Mycorrhizal fungi isolated were tested for their efficacy to induce leafing and genetically determined using ITS-RFLP and sequencing.

Results

Multiple mycorrhizal fungi were repeatedly isolated from a single collar that displayed varying effectiveness in germination percentages and adult leaf length. Additional factors contributed to the isolation of effective mycorrhizal fungi; fungal collection season, year of collection and individual isolates. Surface sterilization only improved the number of isolated mycorrhizal fungi. Dual inoculation did not increase germination. All 59 mycorrhizal fungi effective in germinating seed belonged to one clearly defined ITS (internal transcribed spacer) clade and clustered close to Sebacina vermifera (79–89 % homology). Isolates resulting in the greatest germination were not necessarily those resulting in the greatest survival and growth 1 year after germination.

Conclusion

Single orchid plants contained multiple mycorrhizal fungal strains of one species that had diverse functional differences. These results suggest that our current knowledge of fungal–host specificity may be incomplete due to experimental and analytical limitations. It also suggests that the long-term effectiveness of a mycorrhizal fungus or fungi could only be found by germination and longer-term growth tests rather than genetically.

Keywords: Mycorrhizal fungi; genetic diversity; effectiveness; germination; isolation; ITS; seasonal influences; Caladenia formosa; Orchidaceae

Journal Article.  5926 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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