Liriodendron genome sheds light on angiosperm phylogeny and species-pair differentiation
Liriodendron genome sheds light on angiosperm phylogeny and species-pair differentiation
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DOI：
10.1038/s41477-018-0323-6
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发表时间：
2019-01-01
期刊：
影响因子：
18
通讯作者：
Shi, Jisen
中科院分区：
文献类型：
--
作者：
Chen, Jinhui;Hao, Zhaodong;Shi, Jisen
鹅毛楸属属于木兰科，属于木兰门，是中被子植物的早期分支。然而，木兰属植物与双子科和单子科植物的系统发育关系尚未得到最终解决，因此仍有待确定（1-6）。Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron Liriodendron然而，这些物种的遗传分化和进化轨迹仍有待在全基因组水平上阐明(7)。在这里，我们报道了木兰科植物L. chinense的第一个从头基因组组装。系统发育分析表明，木兰系是由双子系和单子系组成的分支的姐妹，在这三个谱系的共同祖先中发生了迅速的多样化。种群遗传结构分析表明，羊草在中国已分化为东系和西系两个支系。虽然北美的L. tulipifera在遗传上位于两个L. chinense类群之间，但它更接近东部类群。这一结果与表型观察结果一致，表明中国东部和西部类群可能在很久以前就已经分化，可能在L. chinense和L. tulipifera之间的洲际分化之前。遗传多样性分析表明，中国鹅毛草的遗传多样性比郁金香鹅毛草高10倍，表明东亚东西向山脉和长江流域（特别是北纬30度附近）组成的复杂区域比北美东部南北向的山谷更能提供第四纪冰期的成功避难地。
The genus Liriodendron belongs to the family Magnoliaceae, which resides within the magnoliids, an early diverging lineage of the Mesangiospermae. However, the phylogenetic relationship of magnoliids with eudicots and monocots has not been conclusively resolved and thus remains to be determined(1-6). Liriodendron is a relict lineage from the Tertiary with two distinct species-one East Asian (L. chinense (Hemsley) Sargent) and one eastern North American (L. tulipifera Linn)-identified as a vicariad species pair. However, the genetic divergence and evolutionary trajectories of these species remain to be elucidated at the whole-genome level(7). Here, we report the first de novo genome assembly of a plant in the Magnoliaceae, L. chinense. Phylogenetic analyses suggest that magnoliids are sister to the clade consisting of eudicots and monocots, with rapid diversification occurring in the common ancestor of these three lineages. Analyses of population genetic structure indicate that L. chinense has diverged into two lineages-the eastern and western groups-in China. While L. tulipifera in North America is genetically positioned between the two L. chinense groups, it is closer to the eastern group. This result is consistent with phenotypic observations that suggest that the eastern and western groups of China may have diverged long ago, possibly before the intercontinental differentiation between L. chinense and L. tulipifera. Genetic diversity analyses show that L. chinense has tenfold higher genetic diversity than L. tulipifera, suggesting that the complicated regions comprising east-west-orientated mountains and the Yangtze river basin (especially near 30 degrees N latitude) in East Asia offered more successful refugia than the south-north-orientated mountain valleys in eastern North America during the Quaternary glacial period.