Specialized mycorrhizal association between a partially mycoheterotrophic orchid Oreorchis indica and a Tomentella taxon

Kenji Suetsugu, Takashi F. Haraguchi, Akifumi S. Tanabe, Ichiro Tayasu

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


The evolution of full mycoheterotrophy in orchids likely occurs through intermediate stages (i.e., partial mycoheterotrophy or mixotrophy), in which adult plants obtain nutrition through both autotrophy and mycoheterotrophy. However, because of its cryptic manifestation, partial mycoheterotrophy has only been confirmed in slightly more than 20 orchid species. Here, we hypothesized that Oreorchis indica is partially mycoheterotrophic, since (i) Oreorchis is closely related to leafless Corallorhiza, and (ii) it possesses clustered, multi-branched rhizomes that are often found in fully mycoheterotrophic orchids. Accordingly, we investigated the nutritional modes of O. indica in a Japanese subboreal forest by measuring the 13C and 15N abundances and by community profiling of its mycorrhizal fungi. We found that O. indica mycorrhizal samples (all 12 samples from four individuals) were predominantly colonized by a single OTU of the obligate ectomycorrhizal Tomentella (Thelephoraceae). In addition, the leaves of O. indica were highly enriched in both 13C and 15N compared with those of co-occurring autotrophic plants. It was estimated that O. indica obtained 44.4 ± 6.2% of its carbon from fungal sources. These results strongly suggest that in the Oreorchis-Corallorhiza clade, full mycoheterotrophy evolved after the establishment of partial mycoheterotrophy, rather than through direct shifts from autotrophy.

Original languageEnglish
Pages (from-to)243-250
Number of pages8
Issue number2
Publication statusPublished - 2021 Mar


  • C natural abundance
  • N natural abundance
  • Calypsoeae
  • Corallorhiza
  • Ectomycorrhizal fungi
  • Mycorrhiza
  • Orchidaceae
  • Partial mycoheterotrophy
  • Tomentella


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