Identity and specificity of the fungi forming mycorrhizas with the rare mycoheterotrophic orchid Rhizanthella gardneri
Identity and specificity of the fungi forming mycorrhizas with the rare mycoheterotrophic orchid Rhizanthella gardneri
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DOI：
10.1016/j.mycres.2009.07.007
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发表时间：
2009-10-01
影响因子：
--
通讯作者：
Grierson, Pauline
中科院分区：
文献类型：
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作者：
Bougoure, Jeremy;Ludwig, Martha;Grierson, Pauline
完全地下的Rhizanthella gardneri（兰科）是专性的真菌异养意味着它在营养上依赖于与它形成菌根的真菌。此外，R. gardneri据称参与营养共享三方关系，其中其菌根真菌同时与Melaleuca uncinata s.l.虽然R. gardneri在形态学上被鉴定为Thanatephorus gardneri（来自单一分离株），但这种鉴定最近受到质疑。我们试图澄清的菌根真菌的鉴定R。gardneri，使用分子方法，并确定其菌根关系的具体程度。真菌分离物取自所有地点，其中R。gardneri已知存在几乎相同的核糖体DNA（rDNA）序列。真菌分离的rDNA最接近匹配的其他Ceratobasidiales物种，特别是在Ceratobasidium属。然而，结果的解释是困难的，因为我们发现两个不同的ITS序列中的所有菌根真菌菌株的R。我们评估的gardneri。所有R. gardneri很容易形成外生菌根，M. uncinata有限公司物种因此，R. gardneri可以形成营养共享的三方关系，其中R. gardneri与M. uncinata有限公司一种常见的菌根真菌这些发现对于更好地理解R。gardneri分布、演化及其菌根真菌的生态学意义，特别是与养分获取的关系。(C)2009年英国真菌学会。由爱思唯尔有限公司出版。保留所有权利。
Fully subterranean Rhizanthella gardneri (Orchidaceae) is obligately mycoheterotrophic meaning it is nutritionally dependent on the fungus it forms mycorrhizas with. Furthermore, R. gardneri purportedly participates in a nutrient sharing tripartite relationship where its mycorrhizal fungus simultaneously forms ectomycorrhizas with species of Melaleuca uncinata s.l. Although the mycorrhizal fungus of R. gardneri has been morphologically identified as Thanatephorus gardneri (from a single isolate), this identification has been recently questioned. We sought to clarify the identification of the mycorrhizal fungus of R. gardneri, using molecular methods, and to identify how specific its mycorrhizal relationship is. Fungal isolates taken from all sites where R. gardneri is known to occur shared almost identical ribosomal DNA (rDNA) sequences. The fungal isolate rDNA most closely matched that of other Ceratobasidiales species, particularly within the Ceratobasidium genus. However, interpretation of results was difficult as we found two distinct ITS sequences within all mycorrhizal fungal isolates of R. gardneri that we assessed. All mycorrhizal fungal isolates of R. gardneri readily formed ectomycorrhizas with a range of M. uncinata s.l. species. Consequently, it is likely that R. gardneri can form a nutrient sharing tripartite relationship where R. gardneri is connected to autotrophic M. uncinata s.l. by a common mycorrhizal fungus. These findings have implications for better understanding R. gardneri distribution, evolution and the ecological significance of its mycorrhizal fungus, particularly in relation to nutrient acquisition. (C) 2009 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.