Watanabe Shin, Fučíková Karolina, Lewis Louise A, Lewis Paul O
Department of Biology, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan.
Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Storrs, Connecticut 06269 USA.
Am J Bot. 2016 May;103(5):865-75. doi: 10.3732/ajb.1500481. Epub 2016 Apr 27.
Discovery and morphological characterization of a novel epiphytic aquatic green alga increases our understanding of Chaetopeltidales, a poorly known order in Chlorophyceae. Chloroplast genomic data from this taxon reveals an unusual architecture previously unknown in green algae.
Using light and electron microscopy, we characterized the morphology and ultrastructure of a novel taxon of green algae. Bayesian phylogenetic analyses of nuclear and plastid genes were used to test the hypothesized membership of this taxon in order Chaetopeltidales. With next-generation sequence data, we assembled the plastid genome of this novel taxon and compared its gene content and architecture to that of related species to further investigate plastid genome traits.
The morphology and ultrastructure of this alga are consistent with placement in Chaetopeltidales (Chlorophyceae), but a distinct trait combination supports recognition of this alga as a new genus and species-Koshicola spirodelophila gen. et sp. nov. Its placement in the phylogeny as a descendant of a deep division in the Chaetopeltidales is supported by analysis of molecular data sets. The chloroplast genome is among the largest reported in green algae and the genes are distributed on three large (rather than a single) chromosome, in contrast to other studied green algae.
The discovery of Koshicola spirodelophila gen. et sp. nov. highlights the importance of investigating even commonplace habitats to explore new microalgal diversity. This work expands our understanding of the morphological and chloroplast genomic features of green algae, and in particular those of the poorly studied Chaetopeltidales.
一种新型附生水生绿藻的发现及其形态特征描述，增进了我们对绿藻纲中一个鲜为人知的目——毛鞘藻目的了解。该分类单元的叶绿体基因组数据揭示了一种绿藻中前所未知的独特结构。
我们利用光学显微镜和电子显微镜对一种新型绿藻分类单元的形态和超微结构进行了描述。利用核基因和质体基因的贝叶斯系统发育分析来检验该分类单元在毛鞘藻目中的假定归属。通过下一代测序数据，我们组装了这个新型分类单元的质体基因组，并将其基因含量和结构与相关物种进行比较，以进一步研究质体基因组特征。
这种藻类的形态和超微结构与毛鞘藻目（绿藻纲）的分类一致，但独特的性状组合支持将这种藻类认定为一个新属和新物种——螺旋毛鞘藻属新属新种（Koshicola spirodelophila gen. et sp. nov.）。分子数据集分析支持其在系统发育中作为毛鞘藻目一个深度分支的后代的位置。该叶绿体基因组是绿藻中报道的最大的基因组之一，与其他已研究的绿藻不同，其基因分布在三条大染色体上（而非一条）。
螺旋毛鞘藻属新属新种的发现凸显了调查即使是常见生境以探索新的微藻多样性的重要性。这项工作扩展了我们对绿藻形态和叶绿体基因组特征的理解，特别是对研究较少的毛鞘藻目的理解。
