University of Tasmania
141897 - Specific mycorrhizal associations involving the same fungal taxa in common and threatened Caladenia - manuscript.pdf (2.95 MB)

Specific mycorrhizal associations involving the same fungal taxa in common and threatened Caladenia (Orchidaceae): implications for conservation

Download (2.95 MB)
journal contribution
posted on 2023-05-20, 19:32 authored by Reiter, N, Phillips, RD, Nigel SwartsNigel Swarts, Wright, M, Holmes, G, Frances SussmilchFrances Sussmilch, Davis, BJ, Whitehead, MR, Linde, CC

Background and Aims: In orchid conservation, quantifying the specificity of mycorrhizal associations, and establishing which orchid species use the same fungal taxa, is important for sourcing suitable fungi for symbiotic propagation and selecting sites for conservation translocation. For Caladenia subgenus Calonema (Orchidaceae), which contains 58 threatened species, we ask the following questions. (1) How many taxa of Serendipita mycorrhizal fungi do threatened species of Caladenia associate with? (2) Do threatened Caladenia share orchid mycorrhizal fungi with common Caladenia? (3) How geographically widespread are mycorrhizal fungi associated with Caladenia?

Methods: Fungi were isolated from 127 Caladenia species followed by DNA sequencing of the internal transcibed spacer (ITS) sequence locus. We used a 4.1–6 % sequence divergence cut-off range to delimit Serendipita operational taxonomic units (OTUs). We conducted trials testing the ability of fungal isolates to support germination and plant growth. A total of 597 Serendipita isolates from Caladenia, collected from across the Australian continent, were used to estimate the geographic range of OTUs.

Key Results: Across the genus, Caladenia associated with ten OTUs of Serendipita (Serendipitaceae) mycorrhizal fungi. Specificity was high, with 19 of the 23 threatened Caladenia species sampled in detail associating solely with OTU A, which supported plants from germination to adulthood. The majority of populations of Caladenia associated with one OTU per site. Fungal sharing was extensive, with 62 of the 79 Caladenia sampled in subgenus Calonema associating with OTU A. Most Serendipita OTUs were geographically widespread.

Conclusions: Mycorrhizal fungi can be isolated from related common species to propagate threatened Caladenia. Because of high specificity of most Caladenia species, only small numbers of OTUs typically need to be considered for conservation translocation. When selecting translocation sites, the geographic range of the fungi is not a limiting factor, and using related Caladenia species to infer the presence of suitable fungal OTUs may be feasible.


Publication title

Annals of botany










Tasmanian Institute of Agriculture (TIA)


Oxford Univ Press

Place of publication

Great Clarendon St, Oxford, England, Ox2 6Dp

Rights statement

Copyright 2020 the authors. This is a pre-copyedited, author-produced version of an article accepted for publication in following peer review.

Repository Status

  • Restricted

Socio-economic Objectives

Terrestrial biodiversity; Expanding knowledge in the biological sciences