College of Life Sciences, Nanjing Normal University, Nanjing, China.
Department of Geosciences and Global Change Center, Virginia Tech, Blacksburg, VA, USA.
Nat Commun. 2023 Sep 11;14(1):5542. doi: 10.1038/s41467-023-41137-5.
The Viridiplantae comprise two main clades, the Chlorophyta (including a diverse array of marine and freshwater green algae) and the Streptophyta (consisting of the freshwater charophytes and the land plants). Lineages sister to core Chlorophyta, informally refer to as prasinophytes, form a grade of mainly planktonic green algae. Recently, one of these lineages, Prasinodermophyta, which is previously grouped with prasinophytes, has been identified as the sister lineage to both Chlorophyta and Streptophyta. Resolving the deep relationships among green plants is crucial for understanding the historical impact of green algal diversity on marine ecology and geochemistry, but has been proven difficult given the ancient timing of the diversification events. Through extensive taxon and gene sampling, we conduct large-scale phylogenomic analyses to resolve deep relationships and reveal the Prasinodermophyta as the lineage sister to Chlorophyta, raising questions about the necessity of classifying the Prasinodermophyta as a distinct phylum. We unveil that incomplete lineage sorting is the main cause of discordance regarding the placement of Prasinodermophyta. Molecular dating analyses suggest that crown-group green plants and crown-group Prasinodermophyta date back to the Paleoproterozoic-Mesoproterozoic. Our study establishes a plausible link between oxygen levels in the Paleoproterozoic-Mesoproterozoic and the origin of Viridiplantae.
绿藻门包括两个主要分支，即绿藻纲（包括各种各样的海洋和淡水绿藻）和轮藻纲（由淡水轮藻和陆地植物组成）。与核心绿藻同门的谱系，非正式地称为甲藻，形成了一个主要由浮游绿藻组成的等级。最近，这些谱系之一，被称为前甲藻门，被确定为绿藻纲和轮藻纲的姊妹谱系。解析绿藻植物的深层关系对于理解绿藻多样性对海洋生态和地球化学的历史影响至关重要，但由于多样化事件的时间久远，这一问题已被证明颇具难度。通过广泛的分类群和基因采样，我们进行了大规模的系统基因组分析，以解析深层关系，并揭示前甲藻门是绿藻的姊妹谱系，这引发了关于是否有必要将前甲藻门归类为一个独特门的问题。我们揭示了不完全谱系分选是导致前甲藻门位置不一致的主要原因。分子定年分析表明，冠群绿藻和冠群前甲藻起源于古元古代-中元古代。我们的研究在古元古代-中元古代的氧气水平和绿藻植物的起源之间建立了一个合理的联系。
