Phylogenetic Position of Parasitic Chytrids on Diatoms: Characterization of a Novel Clade in Chytridiomycota
Phylogenetic Position of Parasitic Chytrids on Diatoms: Characterization of a Novel Clade in Chytridiomycota
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DOI：
10.1111/jeu.12373
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发表时间：
2017-05
影响因子：
2.2
通讯作者：
K. Seto;M. Kagami;Yousuke Degawa
中科院分区：
文献类型：
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作者：
K. Seto;M. Kagami;Yousuke Degawa
壶菌是一种真正的真菌，以后部单鞭毛游动孢子繁殖。在过去的十年中，环境DNA调查揭示了大量未培养的壶菌以及壶菌门中未描述的目的级新分支。虽然许多物种已被形态学描述，只有一些寄生壶菌的DNA序列数据可从数据库。我们在此讨论了五个文化的寄生壶菌对硅藻Aulacoseira种。和福尔摩沙星藻。为了鉴定所检查的壶菌，使用光学显微镜观察菌体形态。我们还进行了系统发育分析，使用18S，5.8S和28S rDNA序列，以获得它们的系统发育位置。根据其形态特征，两种文化寄生在As。福尔摩沙经鉴定为Rhizophydium acetonicum和Zygorhizidium acetonicum。另外三种感染Aulacoseira spp. (two在Aulacoseira ambigua和Aulacoseira granulata上发现的两个菌株）被认为是Zygorhizidium aff。旋律分子系统发育分析结果表明，该菌与中国的红曲霉属（R. Zygorhizidium属于已知的壶菌目（Chytridiales），而Zygorhizidium的两个物种被置于一个新的分支中，该分支先前被报道为一个未描述的分支，仅由未培养壶菌的环境序列组成。
Chytrids are true fungi that reproduce with posteriorly uniflagellate zoospores. In the last decade, environmental DNA surveys revealed a large number of uncultured chytrids as well as undescribed order‐level novel clades in Chytridiomycota. Although many species have been morphologically described, only some DNA sequence data of parasitic chytrids are available from the database. We herein discuss five cultures of parasitic chytrids on diatoms Aulacoseira spp. and Asterionella formosa. In order to identify the chytrids examined, thallus morphologies were observed using light microscopy. We also conducted a phylogenetic analysis using 18S, 5.8S, and 28S rDNA sequences to obtain their phylogenetic positions. Based on their morphological characteristics, two cultures parasitic on As. formosa were identified as Rhizophydium planktonicum and Zygorhizidium planktonicum. The other three cultures infecting Aulacoseira spp. (two on Aulacoseira ambigua and the other on Aulacoseira granulata) were regarded as Zygorhizidium aff. melosirae. The results of the molecular phylogenetic analysis revealed that R. planktonicum belonged to the known order Chytridiales, while the two species of Zygorhizidium were placed in a novel clade that was previously reported as an undescribed clade composed of only the environmental sequences of uncultured chytrids.