BayCEER - Laboratory of Isotope Biogeochemistry, University of Bayreuth, Bayreuth, 95440, Germany.
Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, HI, 96822, USA.
New Phytol. 2023 Aug;239(4):1449-1463. doi: 10.1111/nph.18991. Epub 2023 Jun 21.
Stable isotope signatures of fungal sporocarps have been instrumental in identifying carbon gains of chlorophyllous orchids from a fungal source. Yet, not all mycorrhizal fungi produce macroscopic sporocarps and frequently fungi of different taxa occur in parallel in orchid roots. To overcome this obstacle, we investigated stable isotope signatures of fungal pelotons extracted from orchid roots and compared these data to the respective orchid and reference plant tissues. Anoectochilus sandvicensis and Epipactis palustris represented specialized or unspecialized rhizoctonia-associated orchids. Epipactis atrorubens and Epipactis leptochila are orchids considered ectomycorrhiza-associated with different preferences for Basidio- and Ascomycota. C enrichment of rhizoctonia pelotons was minor compared with plant tissues and significantly lower than enrichments of pelotons from ectomycorrhizal Epipactis species. N values of pelotons from E. leptochila and E. atrorubens showed similar patterns as known for respective sporocarps of ectomycorrhizal Ascomycota and Basidiomycota, however, with an offset towards lower N enrichments and nitrogen concentrations. Our results suggest an explicit fungal nutrition source of orchids associated with ectomycorrhizal fungi, whereas the low C enrichment in rhizoctonia-associated orchids and fungal pelotons hamper the detection of carbon gains from fungal partners. N isotopic pattern of orchids further suggests a selective transfer of N-enriched protein-nitrogen into orchids.
真菌子实体的稳定同位素特征在鉴定叶绿素兰花从真菌来源获得碳增益方面发挥了重要作用。然而，并非所有的菌根真菌都能产生宏观子实体，而且不同分类群的真菌通常在兰花根系中平行存在。为了克服这一障碍，我们研究了从兰花根系中提取的真菌聚集体的稳定同位素特征，并将这些数据与相应的兰花和参考植物组织进行了比较。Anoectochilus sandvicensis 和 Epipactis palustris 代表了专门的或非专门的与 Rhizoctonia 相关的兰花。Epipactis atrorubens 和 Epipactis leptochila 是被认为与 Basidio 和 Ascomycota 有外生菌根联系的兰花，它们对 Basidio 和 Ascomycota 有不同的偏好。与植物组织相比，Rhizoctonia 聚集体的 C 富集程度较小，且明显低于外生菌根 Epipactis 物种聚集体的富集程度。E. leptochila 和 E. atrorubens 聚集体的 N 值表现出与外生菌根的 Ascomycota 和 Basidiomycota 相应子实体已知的相似模式，然而，它们的 N 富集和氮浓度较低。我们的研究结果表明，与外生菌根真菌相关的兰花有明确的真菌营养来源，而 Rhizoctonia 相关兰花和真菌聚集体中低 C 富集则阻碍了从真菌伙伴中检测到碳增益。兰花的 N 同位素模式进一步表明，N 富集的蛋白质氮被选择性地转移到兰花中。
