Origin of land plants: do conjugating green algae hold the key?
Origin of land plants: do conjugating green algae hold the key?
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DOI：
10.1186/1471-2148-11-104
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发表时间：
2011-04-18
影响因子：
3.4
通讯作者：
Becker B
中科院分区：
文献类型：
--
作者：
Wodniok S;Brinkmann H;Glöckner G;Heidel AJ;Philippe H;Melkonian M;Becker B
陆地栖息地大约在5亿到4.7亿年前被现代陆地植物的祖先殖民。今天，人们普遍认为陆地植物(胚芽植物)是由链藻进化而来的，链藻也被称为轮藻。链藻是绿藻的一种特殊类群，从单细胞鞭毛到形态复杂的形式，如石藻(Charales)。为了更好地了解陆地植物的进化，鉴定与胚芽植物为姊妹群的链藻是至关重要的。轮菌目、鞘毛目或最近的Zygnematales被认为是胚芽植物的姐妹群，然而，尽管多年来的系统发育研究，这个问题仍然没有得到解决，仍然存在争议。在这里，我们使用了来自40个绿色植物分类群(病毒科)的核编码基因(129个蛋白质)的大量数据集，其中包括21个胚芽植物和6个链藻藻类，代表了所有主要的链藻藻类谱系，以研究链藻和胚芽植物的系统发育关系。我们的系统发育分析表明，Zygnematale或由Zygnematale和Coleochaetales组成的一个支系是胚芽植物的姐妹群。我们的分析支持这一观点，即查拉莱斯人不是胚芽植物最接近的近亲。相反，Zygnematales或由Zygnematale和Coleochaetales组成的一个支系最有可能是胚胎植物的姐妹群。尽管这一结果与之前发表的叶绿体基因组系统发育研究一致，但还需要更多的数据来证实这一结论。Zygnematales/胚胎植物姐妹群关系对早期陆地植物进化具有重要意义。如果得到证实，这将使我们能够解决有关病毒植物在征服土地期间的主要适应的重要问题。显然，齐涅马塔目的生物学将在未来重新引起人们的兴趣。
The terrestrial habitat was colonized by the ancestors of modern land plants about 500 to 470 million years ago. Today it is widely accepted that land plants (embryophytes) evolved from streptophyte algae, also referred to as charophycean algae. The streptophyte algae are a paraphyletic group of green algae, ranging from unicellular flagellates to morphologically complex forms such as the stoneworts (Charales). For a better understanding of the evolution of land plants, it is of prime importance to identify the streptophyte algae that are the sister-group to the embryophytes. The Charales, the Coleochaetales or more recently the Zygnematales have been considered to be the sister group of the embryophytes However, despite many years of phylogenetic studies, this question has not been resolved and remains controversial. Here, we use a large data set of nuclear-encoded genes (129 proteins) from 40 green plant taxa (Viridiplantae) including 21 embryophytes and six streptophyte algae, representing all major streptophyte algal lineages, to investigate the phylogenetic relationships of streptophyte algae and embryophytes. Our phylogenetic analyses indicate that either the Zygnematales or a clade consisting of the Zygnematales and the Coleochaetales are the sister group to embryophytes. Our analyses support the notion that the Charales are not the closest living relatives of embryophytes. Instead, the Zygnematales or a clade consisting of Zygnematales and Coleochaetales are most likely the sister group of embryophytes. Although this result is in agreement with a previously published phylogenetic study of chloroplast genomes, additional data are needed to confirm this conclusion. A Zygnematales/embryophyte sister group relationship has important implications for early land plant evolution. If substantiated, it should allow us to address important questions regarding the primary adaptations of viridiplants during the conquest of land. Clearly, the biology of the Zygnematales will receive renewed interest in the future.