Characterization of mycorrhizal fungi isolated from the threatened Cypripedium macranthos in a northern island of Japan: two phylogenetically distinct fungi associated with the orchid
Characterization of mycorrhizal fungi isolated from the threatened Cypripedium macranthos in a northern island of Japan: two phylogenetically distinct fungi associated with the orchid
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DOI：
10.1007/s00572-009-0251-4
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发表时间：
2009-05
期刊：
影响因子：
3.9
通讯作者：
H. Shimura;Mai Sadamoto;Mayumi Matsuura;T. Kawahara;S. Naito;Y. Koda
中科院分区：
文献类型：
--
作者：
H. Shimura;Mai Sadamoto;Mayumi Matsuura;T. Kawahara;S. Naito;Y. Koda
我们从受威胁的兰花塞浦路斯种群中分离到类丝核菌。在隔膜的超微结构观察中，这些分离物具有扁平的无孔亲缘关系，由两个电子致密的膜组成，中间有一个电子透明带，与许多兰科植物的菌根真菌--细根丝核菌(Rhizoctonia Epens)的隔膜超微结构相同。然而，这些菌株的菌丝没有与已知的Repensand测试菌株的菌丝融合，其生长速度不到Repens的一半。在系统发育分析中，这些分离物的rDNA和内转录间隔区(ITS)区序列与分类鉴定的Tulasnella种的rDNA和ITS区序列不同。根据ITS序列，这些分离物被聚为两个组，这两个组与其他塞浦路斯属的分支完全一致。来自欧亚大陆和北美，尽管地理上分离，这表明在塞浦路斯-真菌联合的高度专一性。此外，这两个系统发育群对应于不同发育阶段的两个不同的植物无性系。一个无性系的真菌组成一个群，不属于从另一个无性系分离的另一个真菌群。讨论了在兰花的一生中切换到新的菌根伙伴的可能性。
We isolatedRhizoctonia-like fungi from populations of the threatened orchidCypripedium macranthos. In ultrastructural observations of the septa, the isolates had a flattened imperforate parenthesome consisting of two electron-dense membranes bordered by an internal electron-lucent zone, identical to the septal ultrastructure ofRhizoctonia repens(teleomorphTulasnella), a mycorrhizal fungus of many orchid species. However, hyphae of the isolates did not fuse with those of known tester strains ofR.repensand grew less than half as fast as those ofR.repens. In phylogenetic analyses, sequences for rDNA and internal transcribed spacer (ITS) regions of the isolates were distinct from those of the taxonomically identified species ofTulasnella. On the basis of the ITS sequences, the isolates clustered into two groups that corresponded exactly with the clades demonstrated for otherCypripediumspp. from Eurasia and North America despite the geographical separation, suggesting high specificity in theCypripedium–fungus association. In addition, the two phylogenetic groups corresponded to two different plant clones at different developmental stages. The fungi from one clone constituted one group and did not belong to the other fungal group isolated from the other clone. The possibility of switching to a new mycorrhizal partner during the orchid’s lifetime is discussed.