Abstract
In the mycorrhizal symbiosis, plants exchange photosynthates for mineral nutrients acquired by fungi from the soil. This mutualistic arrangement has been subverted by hundreds of mycorrhizal plant species that lack the ability to photosynthesize. The most numerous examples of this behaviour are found in the largest plant family, the Orchidaceae. Although these non-photosynthetic orchid species are known to be highly specialized exploiters of the ectomycorrhizal symbiosis, photosynthetic orchids are thought to use free-living saprophytic, or pathogenic, fungal lineages. However, we present evidence that putatively photosynthetic orchids from five species which grow in the understorey of forests: (i) form mycorrhizas with ectomycorrhizal fungi of forest trees; and (ii) have stable isotope signatures indicating distinctive pathways for nitrogen and carbon acquisition approaching those of non-photosynthetic orchids that associate with ectomycorrhizal fungi of forest trees. These findings represent a major shift in our understanding of both orchid ecology and evolution because they explain how orchids can thrive in low-irradiance niches and they show that a shift to exploiting ectomycorrhizal fungi precedes viable losses of photosynthetic ability in orchid lineages.
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Selected References
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- Bidartondo M. I., Bruns T. D. Extreme specificity in epiparasitic Monotropoideae (Ericaceae): widespread phylogenetic and geographical structure. Mol Ecol. 2001 Sep;10(9):2285–2295. doi: 10.1046/j.1365-294x.2001.01358.x. [DOI] [PubMed] [Google Scholar]
- Bidartondo M. I., Bruns T. D. Fine-level mycorrhizal specificity in the Monotropoideae (Ericaceae): specificity for fungal species groups. Mol Ecol. 2002 Mar;11(3):557–569. doi: 10.1046/j.0962-1083.2001.01443.x. [DOI] [PubMed] [Google Scholar]
- Bidartondo Martin I., Bruns Thomas D., Weiss Michael, Sérgio Cecília, Read David J. Specialized cheating of the ectomycorrhizal symbiosis by an epiparasitic liverwort. Proc Biol Sci. 2003 Apr 22;270(1517):835–842. doi: 10.1098/rspb.2002.2299. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bidartondo Martin I., Redecker Dirk, Hijri Isabelle, Wiemken Andres, Bruns Thomas D., Domínguez Laura, Sérsic Alicia, Leake Jonathan R., Read David J. Epiparasitic plants specialized on arbuscular mycorrhizal fungi. Nature. 2002 Sep 26;419(6905):389–392. doi: 10.1038/nature01054. [DOI] [PubMed] [Google Scholar]
- Gardes M., Bruns T. D. ITS primers with enhanced specificity for basidiomycetes--application to the identification of mycorrhizae and rusts. Mol Ecol. 1993 Apr;2(2):113–118. doi: 10.1111/j.1365-294x.1993.tb00005.x. [DOI] [PubMed] [Google Scholar]
- Selosse Marc-André, WEIss Michael, Jany Jean-Luc, Tillier Annie. Communities and populations of sebacinoid basidiomycetes associated with the achlorophyllous orchid Neottia nidus-avis (L.) L.C.M. Rich. and neighbouring tree ectomycorrhizae. Mol Ecol. 2002 Sep;11(9):1831–1844. doi: 10.1046/j.1365-294x.2002.01553.x. [DOI] [PubMed] [Google Scholar]
- Taylor D. L., Bruns T. D. Independent, specialized invasions of ectomycorrhizal mutualism by two nonphotosynthetic orchids. Proc Natl Acad Sci U S A. 1997 Apr 29;94(9):4510–4515. doi: 10.1073/pnas.94.9.4510. [DOI] [PMC free article] [PubMed] [Google Scholar]
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