Green orchids feed on sunlight and fungi

2016-02-05

Green plants are commonly considered as covering their carbon demand through photosynthesis. Only for very few plants simultaneous carbon gains from photosynthesis and heterotrophic use of carbon from other organisms have previously been identified. With a new isotopic tracer Prof. Gerhard Gebauer and his team from the BayCEER-Laboratory of Isotope Biogeochemistry showed, that green orchids often also use carbon from fungi.

Approaches of elucidating carbon gain by plants from two origins mostly used carbon stable isotope natural abundances. Unfortunately, heterotrophic carbon sources are not always sufficiently distinguished in their isotope abundance from carbon gained through photosynthesis. The researchers used as an alternative approach the analysis of hydrogen stable isotopes to elucidate heterotrophic organic matter gain by putatively autotrophic orchids. Enrichment in heavy hydrogen isotopes without uniform enrichment in heavy carbon isotopes was found for a set of orchid species previously assumed as autotrophic. This finding indicates much wider distribution of partially heterotrophic carbon gain among green orchids from their mycorrhizal fungi than previously assumed and provides perspectives of identifying partial heterotrophy also among other plant groups.

Article "Partial mycoheterotrophy is more widespread among orchids than previously assumed" (New Phytologist, 02/2016):

http://onlinelibrary.wiley.com/wol1/doi/10.1111/nph.13865/full