Carbon and nitrogen gain during the growth of orchid seedlings in nature.
Carbon and nitrogen gain during the growth of orchid seedlings in nature.
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DOI：
10.1111/nph.12688
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发表时间：
2014-04
期刊：
影响因子：
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通讯作者：
Marcus Stöckel;T. Těšitelová;J. Jersáková;M. Bidartondo;G. Gebauer
中科院分区：
文献类型：
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作者：
Marcus Stöckel;T. Těšitelová;J. Jersáková;M. Bidartondo;G. Gebauer
兰花的发芽和生长依赖于菌根真菌提供的碳 (C) 和养分。成年后，大多数兰花似乎变得自养。为了比较真菌异养幼苗和成虫中真菌的碳和氮 (N) 增益比例，我们在现场检查了与外生菌根和腐生真菌相关的兰花幼苗和成虫中的 C 和 N 稳定同位素组成。使用一种新的高度敏感的方法，我们测量了属于不同功能群的四种兰花的幼苗和成虫的同位素组成：与狭窄或广泛的外生菌根真菌相关的完全和部分菌异养兰花，以及两种仅与腐生真菌相关的假定自养兰花的成虫。与外生菌根真菌相关的兰花幼苗富含 (13) C 和 (15) N，与完全霉菌异养成虫相似。腐生相关兰花的幼苗也富含 (13) C 和 (15) N，但出乎意料的是，它们的富集量显着较低，使得它们很难与各自的成年阶段和邻近的自养植物区分开。我们得出的结论是，仅根据 C 和 N 同位素组成不能明确鉴定腐生相关兰花中的部分真菌异养。因此，部分真菌异养在兰花中的分布可能比迄今为止假设的要广泛得多。
For germination and establishment, orchids depend on carbon (C) and nutrients supplied by mycorrhizal fungi. As adults, the majority of orchids then appear to become autotrophic. To compare the proportional C and nitrogen (N) gain from fungi in mycoheterotrophic seedlings and in adults, here we examined in the field C and N stable isotope compositions in seedlings and adults of orchids associated with ectomycorrhizal and saprotrophic fungi. Using a new highly sensitive approach, we measured the isotope compositions of seedlings and adults of four orchid species belonging to different functional groups: fully and partially mycoheterotrophic orchids associated with narrow or broad sets of ectomycorrhizal fungi, and two adult putatively autotrophic orchids associated exclusively with saprotrophic fungi. Seedlings of orchids associated with ectomycorrhizal fungi were enriched in (13) C and (15) N similarly to fully mycoheterotrophic adults. Seedlings of saprotroph-associated orchids were also enriched in (13) C and (15) N, but unexpectedly their enrichment was significantly lower, making them hardly distinguishable from their respective adult stages and neighbouring autotrophic plants. We conclude that partial mycoheterotrophy among saprotroph-associated orchids cannot be identified unequivocally based on C and N isotope compositions alone. Thus, partial mycoheterotrophy may be much more widely distributed among orchids than hitherto assumed.