Natural ¹³C and ¹⁵N abundance of field‐collected fungi and their ecological implications

Abstract

The natural abundance of "$C and "&N was measured in basidiocarps of at least 115 species in 88 genera of ectomycorrhizal, wood-decomposing and litter-decomposing fungi from Japan and Malaysia. The natural abundance of "$C and "&N was also measured in leaves, litter, soil and wood from three different sites. "&N and "$C were enriched in ectomycorrhizal and wood-decomposing fungi, respectively, relative to their substrates. Ectomycorrhizal and wood-decomposing fungi could be distinguished on the basis of their δ"$C and δ"&N signatures. Although there was high variability in the isotopic composition of fungi, the following isotopeenrichment factors (ε, meanpSD) of the fungi relative to substrates were observed : ε ectomycorrhizal fungi/litter l 6.1p0.4= "&N ε ectomycorrhizal fungi/wood l 1.4p0.8= "$C ε wood-decomposing fungi/wood l k0.6p0.7= "&N ε wood-decomposing fungi/wood l 3.5p0.9= "$C The basis of isotope fractionation in C metabolism from wood to wood-decomposing fungus is discussed.

Stratégie saprophyte ou symbiotique durant le développement d’ascocarpes de truffes dans une truffière à chêne vert. Une réponse basée sur l’abondance naturelle du 13C et du 15N

“…As reported by several authors (Gebauer and Taylor, 1999;Henn and Chapela, 2001;Hobbie et al, 1999Hobbie et al, , 2001Högberg, 1997;Kohzu et al, 1999;Taylor et al, 2003, Trudell et al, 2004Zeller et al, 2007), δ 13 C values differed between sporophores of saprotrophic and ectomycorrhizal fungi. Sporophores of the two saprotrophic fungi from the Châteauvert site showed a 13 C enrichment compared to their substrates.…”

“…Fungal sheaths were 2.4 to 6.4% enriched compared to the root core. Other studies have confirmed that sporophores of ectomycorrhizal fungi are often more enriched in 15 N than sporophores of saprotrophic fungi, whereas sporophores of saprotrophic fungi are almost always enriched in 13 C compared to sporophores of ectomycorrhizal fungi (Hobbie et al, 1999;2002;Kohzu et al, 1999;2000;Taylor et al, 2003;Trudell et al, 2004). Lilleskov et al (2002) demonstrated that isotope signatures reflect ecophysiological functions.…”

“…Although the relative contribution of the C and N sources and the different internal processes involved in the fractionation of 13 C and 15 N remain unclear, it appears that the analysis of natural abundance of C and N isotopes could provide insight into the respective trophic roles of saprotrophic versus ectomycorrhizal fungi (Gebauer and Taylor, 1999;2005;Högberg et al, 1996;Kohzu et al, 1999;Taylor et al, 2003;Trudell et al, 2004;Zeller et al, 2007).…”

Ectomycorrhizal fungal taxa differing in response to nitrogen deposition also differ in pure culture organic nitrogen use and natural abundance of nitrogen isotopes

“…As in the present study, Tricholoma and Cortinarius had significantly higher δ 15 N than Lactarius, Laccaria and Russula (P < 0.05 for each comparison). By contrast, Kohzu et al (1999) found no taxonomic patterns of N isotopic signature. However, they compared taxa at the family rather than genus level, and compared fungi from different sites, both of which could obscure taxonomic patterns.…”

“…Russula ). EMF taxa differ in their N isotopic signatures (Taylor et al , 1997;Gebauer & Taylor, 1999;Hobbie et al , 1999;Kohzu et al , 1999). Nitrogen isotopes may provide an independent line of evidence regarding N-use patterns if the combination of soil N pool signatures and physiological mechanisms of isotopic alteration during uptake, transformations, transfers and losses lead to a consistent isotopic distinction among physiological classes of fungi.…”