Stable isotope natural abundances of fungal hyphae extracted from the roots of arbuscular mycorrhizal mycoheterotrophs and rhizoctonia‐associated orchids

Novel insights into orchid mycorrhiza functioning from stable isotope signatures of fungal pelotons

“…Together with Gomes et al . (2023), this study provides the first 15 N and 13 C natural abundance stable isotope composition data of fungal pelotons, the typical morphological feature of mycorrhizal fungi in orchid roots (Fig. 1b,c).…”

“…Indeed, as hypothesized, enrichment in 13 C of pelotons extracted from A. sandvicensis and E. palustris was similar irrespective of fungal specificity and considerably smaller than ɛ 13 C of pelotons isolated from the forest‐dwelling, ECM‐associated E. leptochila and E. atrorubens . Although pelotons of all investigated orchid species (including Ophrys insectifera and Orchis militaris , Gomes et al ., 2023) displayed by c . 3‰ higher mean ɛ 13 C values than leaves of respective reference plants, the relatively small 13 C enrichment of rhizoctonia pelotons extracted from A. sandvicensis and E. palustris may explain the inconspicuous 13 C enrichment of rhizoctonia‐associated orchids.…”

“…As suspected, 15 N values of pelotons extracted from E. leptochila and E. atrorubens roots showed the same array as fruit bodies of ECM Ascomycota and ECM Basidiomycota, their dominant mycorrhizal root fungi (Gebauer et al ., 2016; Schiebold et al ., 2017). However, pelotons of rhizoctonia‐associated orchids ( A. sandvicensis and E. palustris ) were least enriched in 15 N, a pattern being reflected in the 15 N isotopic signature of the orchid leaves and also reported for rhizoctonia‐associated O. insectifera L. and O. militaris L. (Gomes et al ., 2023).…”

“…With this investigation, we present the first natural abundance of 15 N and 13 C data of fungal pelotons isolated from rhizoctonia‐associated orchids (contemporaneous with Gomes et al ., 2023) and of pelotons extracted from orchids entangled in ectomycorrhizal networks with Ascomycota and/or Basidiomycota. Because small 13 C enrichment of rhizoctonia pelotons is obviously not suited as a nutrition indicator of rhizoctonia‐associated orchids, we suggest refining the 2 H approach with regards to pelotons.…”

“…Gomes et al . (2023) focused on arbuscular mycorrhizal fungi and orchid mycorrhizal rhizoctonia fungi and thus on gaining stable isotope data of mycorrhizal fungi which do not produce fruit bodies and can only be extracted from plant roots. In this study, we centred specifically upon orchid mycorrhiza.…”