Actin phylogeny identifies Mesostigma viride as a flagellate ancestor of the land plants
Actin phylogeny identifies Mesostigma viride as a flagellate ancestor of the land plants
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DOI：
10.1007/pl00006410
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发表时间：
1998-11-01
影响因子：
3.9
通讯作者：
Berning-Koch, W
中科院分区：
文献类型：
--
作者：
Bhattacharya, D;Weber, K;Berning-Koch, W
绿藻和陆地植物的进化史可以追溯到一个独特的共同祖先。这个“绿色谱系”在系统发育上被细分为两个不同的组合，绿藻和链藻。绿藻门包括绿藻门、绿藻门、绿藻门和绿藻门，而链藻门包括藻门、苔藓植物、蕨类植物和所有其他多细胞陆地植物（胚植物）。Prasinophyceae被认为包含绿色谱系中最早的分化。利用rDNA序列进行系统发育分析，确定了该植物是一个在绿藻底部分化的副植物分类群。然而，关于链门的鞭毛祖先的身份，rDNA分析提供了模糊的结果。我们测序了来自dubia Scherffelia (Prasinophyceae), Coleochaete scutata, Spirogyra sp. （Charophyceae）的肌动蛋白编码cdna，以及Mesostigma viride （Prasinophyceae）的单拷贝肌动蛋白基因。系统发育分析表明中柱头是链门中最早的分支，并为该谱系的鳞片、双鞭毛、单细胞祖先提供了直接证据。这一结果得到了两个保守的肌动蛋白编码区内含子（位置20- 3,152 -1）和一个位于肌动蛋白基因5'-未翻译区域的内含子的支持，这是中柱头和胚胎共有的。
Green algae and land plants trace their evolutionary history to a unique common ancestor. This ''green lineage'' is phylogenetically subdivided into two distinct assemblages, the Chlorophyta and the Streptophyta. The Chlorophyta includes the Chlorophyceae, Trebouxiophyceae, Ulvophyceae, and Prasinopohyceae, whereas the Streptophyta includes the Charophyceae plus the bryophytes, ferns, and all other multicellular land plants (Embryophyta). The Prasinophyceae is believed to contain the earliest divergeneces within the green lineage. Phylogenetic analyses using rDNA sequences identify the prasinophytes as a paraphyletic taxon that diverges at the base of the Chlorophyta. rDNA analyses, however, provide ambiguous results regarding the identity of the flagellate ancestor of the Streptophyta. We have sequenced the actin-encoding cDNAs from Scherffelia dubia (Prasinophyceae), Coleochaete scutata, Spirogyra sp. (Charophyceae), and the single-copy actin gene from Mesostigma viride (Prasinophyceae). Phylogenetic analyses show Mesostigma to be the earliest divergence within the Streptophyta and provide direct evidence for a scaly, biflagellate, unicellular ancestor for this lineage. This result is supported by the existence of two conserved actin-coding region introns (positions 20-3, 152-1), and one intron in the 5'-untranslated region of the actin gene shared by Mesostigma and the embryophytes.