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Continental-scale distribution and diversity of Ceratobasidium orchid mycorrhizal fungi in Australia


Freestone, MW and Swarts, ND and Reiter, N and Tomlinson, S and Sussmilch, F and Wright, MM and Holmes, GD and Phillips, RD and Linde, CC, Continental-scale distribution and diversity of Ceratobasidium orchid mycorrhizal fungi in Australia , Annals of Botany, 128, (3) pp. 329-343. ISSN 0305-7364 (2021) [Refereed Article]

Copyright Statement

The Author(s) 2021.

DOI: doi:10.1093/aob/mcab067


Background and Aims

Mycorrhizal fungi are a critical component of the ecological niche of most plants and can potentially constrain their geographical range. Unlike other types of mycorrhizal fungi, the distributions of orchid mycorrhizal fungi (OMF) at large spatial scales are not well understood. Here, we investigate the distribution and diversity of Ceratobasidium OMF in orchids and soils across the Australian continent.


We sampled 217 Ceratobasidium isolates from 111 orchid species across southern Australia and combined these with 311 Ceratobasidium sequences from GenBank. To estimate the taxonomic diversity of Ceratobasidium associating with orchids, phylogenetic analysis of the ITS sequence locus was undertaken. Sequence data from the continent-wide Australian Microbiome Initiative were used to determine the geographical range of operational taxonomic units (OTUs) detected in orchids, with the distribution and climatic correlates of the two most frequently detected OTUs modelled using MaxEnt.

Key Results

We identified 23 Ceratobasidium OTUs associating with Australian orchids, primarily from the orchid genera Pterostylis, Prasophyllum, Rhizanthella and Sarcochilus. OTUs isolated from orchids were closely related to, but distinct from, known pathogenic fungi. Data from soils and orchids revealed that ten of these OTUs occur on both east and west sides of the continent, while 13 OTUs were recorded at three locations or fewer. MaxEnt models suggested that the distributions of two widespread OTUs are correlated with temperature and soil moisture of the wettest quarter and far exceeded the distributions of their host orchid species.


Ceratobasidium OMF with cross-continental distributions are common in Australian soils and frequently have geographical ranges that exceed that of their host orchid species, suggesting these fungi are not limiting the distributions of their host orchids at large spatial scales. Most OTUs were distributed within southern Australia, although several OTUs had distributions extending into central and northern parts of the continent, illustrating their tolerance of an extraordinarily wide range of environmental conditions.

Item Details

Item Type:Refereed Article
Keywords:Ceratobasidium, orchid, fungi, scale, distribution, diversity, species distribution model, mycorrhiza
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Population ecology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Horticultural crops
Objective Field:Ornamentals, natives, flowers and nursery plants
UTAS Author:Swarts, ND (Dr Nigel Swarts)
UTAS Author:Sussmilch, F (Dr Frances Sussmilch)
ID Code:151911
Year Published:2021
Web of Science® Times Cited:4
Deposited By:TIA - Research Institute
Deposited On:2022-08-08
Last Modified:2022-09-15

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