Journal Article

Mycoheterotrophy evolved from mixotrophic ancestors: evidence in <i>Cymbidium</i> (Orchidaceae)

Hiroyuki Motomura, Marc-André Selosse, Florent Martos, Akira Kagawa and Tomohisa Yukawa

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 106, issue 4, pages 573-581
Published in print October 2010 | ISSN: 0305-7364
Published online August 2010 | e-ISSN: 1095-8290 | DOI:
Mycoheterotrophy evolved from mixotrophic ancestors: evidence in Cymbidium (Orchidaceae)

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


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Background and Aims

Nutritional changes associated with the evolution of achlorophyllous, mycoheterotrophic plants have not previously been inferred with robust phylogenetic hypotheses. Variations in heterotrophy in accordance with the evolution of leaflessness were examined using a chlorophyllous–achlorophyllous species pair in Cymbidium (Orchidaceae), within a well studied phylogenetic background.


To estimate the level of mycoheterotrophy in chlorophyllous and achlorophyllous Cymbidium, natural 13C and 15N contents (a proxy for the level of heterotrophy) were measured in four Cymbidium species and co-existing autotrophic and mycoheterotrophic plants and ectomycorrhizal fungi from two Japanese sites.

Key Results

δ13C and δ15N values of the achlorophyllous C. macrorhizon and C. aberrans indicated that they are full mycoheterotrophs. δ13C and δ15N values of the chlorophyllous C. lancifolium and C. goeringii were intermediate between those of reference autotrophic and mycoheterotrophic plants; thus, they probably gain 30–50 % of their carbon resources from fungi. These data suggest that some chlorophyllous Cymbidium exhibit partial mycoheterotrophy (= mixotrophy).


It is demonstrated for the first time that mycoheterotrophy evolved after the establishment of mixotrophy rather than through direct shifts from autotrophy to mycoheterotrophy. This may be one of the principal patterns in the evolution of mycoheterotrophy. The results also suggest that the establishment of symbiosis with ectomycorrhizal fungi in the lineage leading to mixotrophic Cymbidium served as pre-adaptation to the evolution of the mycoheterotrophic species. Similar processes of nutritional innovations probably occurred in several independent orchid groups, allowing niche expansion and radiation in Orchidaceae, probably the largest plant family.

Keywords: Mycoheterotrophy; nutritional mode; evolution; Cymbidium; Orchidaceae; symbiosis; mycorrhizal fungi; δ15N, δ13C

Journal Article.  5239 words.  Illustrated.

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

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