Changing partners in the dark: isotopic and molecular evidence of ectomycorrhizal liaisons between forest orchids and trees
Changing partners in the dark: isotopic and molecular evidence of ectomycorrhizal liaisons between forest orchids and trees
复制标题
DOI：
10.1098/rspb.2004.2807
复制
发表时间：
2004-09-07
影响因子：
4.7
通讯作者：
Read, DJ
中科院分区：
文献类型：
--
作者：
Bidartondo, MI;Burghardt, B;Read, DJ
在菌根共生中，植物将光合产物交换为真菌从土壤中获取的矿质养分。这种互利共生的安排已被数百种缺乏光合作用能力的菌根植物物种所破坏。这种行为的例子最多见于最大的植物科——兰科。尽管已知非光合兰花物种是高度专业化的外生菌根共生利用者，但光合兰花被认为利用自由生活的腐生或致病真菌谱系。然而，我们提出的证据表明，生长在森林下层的五种光合兰花（i）与林树的外生菌根真菌形成菌根，并且（ii）具有稳定同位素特征，表明氮和碳的获取途径与与林树的外生菌根真菌相关的非光合兰花的独特途径相似。这些发现代表了我们对兰花生态和进化的理解的重大转变，因为它们解释了兰花如何在低辐照度生态位中茁壮成长，并且表明，在兰花谱系中光合作用能力明显丧失之前，转向利用外生菌根真菌。
In the mycorrhizal symbiosis, plants exchange photosynthates for mineral nutrients acquired by fungi from the soil. This mutualistic arrangement has been subverted by hundreds of mycorrhizal plant species that lack the ability to photosynthesize. The most numerous examples of this behaviour are found in the largest plant family, the Orchidaceae. Although non-photosynthetic orchid species are known to be highly specialized exploiters of the ectomycorrhizal symbiosis, photosynthetic orchids are thought to use free-living saprophytic or pathogenic fungal lineages. However, we present evidence that putatively photosynthetic orchids from five species that grow in the understorey of forests (i) form mycorrhizas with ectomycorrhizal fungi of forest trees and (ii) have stable-isotope signatures indicating distinctive pathways for nitrogen and carbon acquisition approaching those of non-photo synthetic orchids that associate with ectomycorrhizal fungi of forest trees. These findings represent a major shift in our understanding of both orchid ecology and evolution because they explain how orchids can thrive in low-irradiance niches and they show that a shift to exploiting ectomycorrhizal fungi precedes viable losses of photosynthetic ability in orchid lineages.