April 21, 2020  |  

Liriodendron genome sheds light on angiosperm phylogeny and species-pair differentiation.

Authors: Chen, Jinhui and Hao, Zhaodong and Guang, Xuanmin and Zhao, Chenxi and Wang, Pengkai and Xue, Liangjiao and Zhu, Qihui and Yang, Linfeng and Sheng, Yu and Zhou, Yanwei and Xu, Haibin and Xie, Hongqing and Long, Xiaofei and Zhang, Jin and Wang, Zhangrong and Shi, Mingming and Lu, Ye and Liu, Siqin and Guan, Lanhua and Zhu, Qianhua and Yang, Liming and Ge, Song and Cheng, Tielong and Laux, Thomas and Gao, Qiang and Peng, Ye and Liu, Na and Yang, Sihai and Shi, Jisen

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 determined1-6. 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 level7. 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°?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.

Journal: Nature plants
DOI: 10.1038/s41477-018-0323-6
Year: 2019

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