The 13C content of the orchid Epipactis palustris (L.) Crantz responds to light as in autotrophic plants
The 13C content of the orchid Epipactis palustris (L.) Crantz responds to light as in autotrophic plants
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DOI：
10.1080/23818107.2017.1418430
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发表时间：
2018-01
期刊：
影响因子：
1.5
通讯作者：
F. Lallemand;Alicja E. Robionek;P. Courty;M. Selosse
中科院分区：
文献类型：
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作者：
F. Lallemand;Alicja E. Robionek;P. Courty;M. Selosse
摘要大多数温带绿色兰花与丝核菌属真菌形成菌根，被认为是自养的。然而，有些兰花与真菌有关，这些真菌也与周围的树木形成外生菌根，并从这些真菌中获得部分碳。这种进化衍生的条件，称为混合营养，其特征是天然的13 C富集和高N含量。一些兰花属显示这两种症状取决于物种。在这里，我们进一步记录的同位素特征的一个丝核菌相关的物种，Epipactis palustris，在一个属，否则包括许多mixotrophic兰花。首先，E. palustris在两个湿地网站从北方欧洲显示出类似的轻微亏损13 C丰度和相同的N含量与周围的自养植物相比，证实了发表的结果对这个物种。第二，在较暗的条件下生长的一些个体（63%的辐射减少）显示出13 C丰度的减少，正如预期的那样（并在同一地点观察到）。后一结果扩展了以前对其他与丝核菌相关的兰花物种的观察。我们讨论了我们的研究结果与当前的观点的两个营养综合征的绿色兰花（特别是，与怀疑的自养的丝核菌属相关物种）和Epipactis的发育框架中，发展次级mixotrophy。后一种观察结果表明，Neottieae族反复进化混合营养。
Abstract Most temperate green orchids form mycorrhizae with rhizoctonias fungi and are considered autotrophic. Some orchids, however, associate with fungi that also form ectomycorrhizae with surrounding trees and derive part of their carbon from these fungi. This evolutionarily derived condition, called mixotrophy, is characterized by natural 13C enrichment and high N content. Some orchid genera display both syndromes depending on species. Here, we further document the isotopic features of a rhizoctonias-associated species, Epipactis palustris, in a genus otherwise encompassing many mixotrophic orchids. First, E. palustris in two wetland sites from Northern Europe displayed similar to slightly-depleted 13C abundance and identical N content as compared with surrounding autotrophic plants, confirming published results on this species. Second, some individuals growing in darker conditions (63% reduced irradiation) revealed a decrease of 13C abundance as expected (and observed at the same place) for autotrophic plants. The latter result expands previous observations on other rhizoctonias-associated orchid species. We discuss our results in relationship with the current views of the two nutritional syndromes of green orchids (especially, with the doubts on autotrophy of rhizoctonias-associated species) and in the framework of the phylogeny of Epipactis that evolved secondarily mixotrophy. The latter observation entails that the tribe Neottieae repeatedly evolved mixotrophy.