Fungal partner shifts during the evolution of mycoheterotrophy in Neottia
Fungal partner shifts during the evolution of mycoheterotrophy in Neottia
复制标题
DOI：
10.3732/ajb.1600063
复制
发表时间：
2016-09-01
影响因子：
3
通讯作者：
Yukawa, Tomohisa
中科院分区：
文献类型：
--
作者：
Yagame, Takahiro;Ogura-Tsujita, Yuki;Yukawa, Tomohisa
研究前提：以前很少有研究探讨了如何在从自养到异养的进化过程中，基于系统发育假说的真菌生物的变化。Neottia（兰科）包括多叶的自养种和相关的无叶的真菌异养种，它们之间的系统发育关系已经阐明。因此，Neottia是研究上述问题的合适分类群。在这里，我们澄清了Neottia植物中的真菌的多样性，并阐明了共生协会的mycoheterotrophy.METHODS的演变过程中的字符的变化：我们测序的核核糖体（nr）DNA的内转录间隔区（ITS）区域的Neottia植物的真菌。此外，我们从每个真菌操作分类单位（OTU）中选择了一个代表性的DNA样品，并用它来扩增大亚基（LSU）nrDNA序列。系统发育分析的Sebacinales（担子菌类），占主导地位的真菌Neottia，进行和样品为基础的稀疏曲线产生的观察到的真菌丰富的每个OTU.KEY结果：在Neottia有叶和无叶的物种分别与Sebacinales组B和Sebacinales组A，分别。真菌的合作伙伴的组成和特异性水平各不相同Neottia species.CONCLUSIONS：真菌的合作伙伴组成和特异性水平的变化与形态在有叶和无叶Neottia物种。特别是，菌根协会可能从Sebacinales组B到A组从自养到mycoheterotrophy的演变过程中。在其他植物类群的真菌异养的进化中也有报道称，向Sebacinales A组的合作伙伴转移，这表明与真菌异养的进化相关的真菌类群的趋同。
PREMISE OF THE STUDY: Few previous studies have examined how mycobionts change during the evolution from autotrophy to mycoheterotrophy based on phylogenetic hypotheses. Neottia (Orchidaceae) comprises leafy species that are autotrophic and related leafless mycoheterotrophic species, and the phylogenetic relationships among them have been clarified. Accordingly, Neottia is a suitable taxon for investigating the question above. Here we clarified the diversity of mycobionts in Neottia plants and elucidated changes in the character of symbiotic associations during the evolution of mycoheterotrophy.METHODS: We sequenced the internal transcribed spacer (ITS) regions of nuclear ribosomal (nr) DNA for mycobionts of Neottia plants. Furthermore, we selected one representative DNA sample from each fungal operational taxonomic unit (OTU) and used it to amplify the large subunit (LSU) nrDNA sequences. Phylogenetic analyses of Sebacinales (basidiomycetes), the dominant mycobiont of Neottia, were conducted and sample-based rarefaction curves generated for the observed mycobiont richness on each OTU.KEY RESULTS: Leafy and leafless species in Neottia were associated with Sebacinales Group B and Sebacinales Group A, respectively. The composition and specificity level of fungal partners varied among Neottia species.CONCLUSIONS: Fungal partner composition and specificity level changed with speciation in both leafy and leafless Neottia species. In particular, mycorrhizal associations likely shifted from Sebacinales Group B to Group A during the evolution from autotrophy to mycoheterotrophy. Partner shifts to Sebacinales Group A have also been reported in the evolution of mycoheterotrophy of other plant groups, suggesting that convergence to this fungal group occurs in association with the evolution of mycoheterotrophy.