15N and 13C natural abundance of autotrophic and mycoheterotrophic orchids provides insight into nitrogen and carbon gain from fungal association
15N and 13C natural abundance of autotrophic and mycoheterotrophic orchids provides insight into nitrogen and carbon gain from fungal association
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DOI：
10.1046/j.1469-8137.2003.00872.x
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发表时间：
2003-10-01
期刊：
影响因子：
9.4
通讯作者：
Meyer, M
中科院分区：
文献类型：
--
作者：
Gebauer, G;Meyer, M
虽然菌根真菌被认为是无叶绿素（菌类异养）兰花中氮（N）和碳（C）的来源，但自养兰花中这些元素的来源尚不清楚。我们测定了 N 和 C 的稳定同位素丰度，以量化这两个功能组和独特菌根类型的非兰科植物中不同来源的增益。每种植物的叶子采集自欧洲的四个森林和四个草原地点。测定了其组织和相关土壤的 N 和 C 同位素丰度以及总 N 浓度。真菌异养兰花的 N-15（epsilon(MHO-R) 11.5 千分之一）和 C-13（epsilon(MHO-R) = 8.4%）比共存的非兰花显着更丰富。自养兰花的 delta(15)N 和 delta(13)C 特征范围从非兰花的典型值到真菌异养兰花的更具代表性。真菌来源的 N 和 C 的利用可能解释了真菌异养植物中 N-15 和 C-13 的相对富集。使用线性双源同位素混合模型来估计自养兰花从其真菌伙伴中获得的 N 和 C 增益。在假定的自养物种中，Cephalanthera damasodium 通过真菌途径获得了最多的 N 和 C，但其他几种物种也属于部分真菌异养类别。
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 N-15 (epsilon(MHO-R) 11.5parts per thousand) and C-13 (epsilon(MHO-R) = 8.4%.) than co-occurring non-orchids. delta(15)N and delta(13)C 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 N-15 and C-13 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.