Uni-Bayreuth grafik-uni-bayreuth


Gebauer, G; Meyer, M: 15N and 13C natural abundance of autotrophic and myco-heterotrophic orchids provides insight into nitrogen and carbon gain from fungal association, New Phytologist, 160, 209-223 (2003), doi:10.1046/j.1469-8137.2003.00872.x
Stichworte: delta C-13, delta N-15; forest, grassland, myco-heterotrophy,mycorrhiza; orchids,stable isotopes
Whereas mycorrhizal fungi are acknowledged to be the sources of nitrogen (N) and carbon (C) in achlorophyllous (myco-heterotrophic) orchids, the sources of these elements in autotrophic orchids are unknown. We have determined the stable isotope abundance of N and C to quantify their gain from different sources in these two functional groups and in non-orchids of distinctive mycorrhizal types. Leaves of each plant were collected from four forest and four grassland sites in Europe. The N and C isotope abundance, and total N concentrations of their tissues and of associated soils were determined.

Myco-heterotrophic orchids were significantly more enriched in 15N (epsilon(MHO-R) 11.5o/oo) and 13C (epsilon(MHO-R) = 8.4o/oo.) than co-occurring non-orchids. delta15N and delta13C signatures of autotrophic orchids ranged from values typical of non-orchids to those more representative of myco-heterotrophic orchids.

Utilization of fungi-derived N and C probably explains the relative 15N and 13C enrichment in the myco-heterotrophs. A linear two-source isotopic mixing model was used to estimate N and C gain of autotrophic orchids from their fungal associates. Of the putatively autotrophic species, Cephalanthera damasonium obtained the most N and C by the fungal route, but several other species also fell into the partially myco-heterotrophic category.

Letzte Änderung 29.01.2013