Plant Diversity ›› 2022, Vol. 44 ›› Issue (03): 262-270.DOI: 10.1016/j.pld.2021.08.004

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Lycophyte transcriptomes reveal two whole-genome duplications in Lycopodiaceae: Insights into the polyploidization of Phlegmariurus

Zeng-Qiang Xiaa,b,c,d, Zuo-Ying Weia,e, Hui Shenc, Jiang-Ping Shua, Ting Wanga, Yu-Feng Gua,f, Amit Jaisig, Yue-Hong Yana,d   

  1. a Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, Shenzhen, 518114, China;
    b CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China;
    c Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, 3888 Chenhua Road Songjiang, Shanghai, 201602, China;
    d University of Chinese Academy of Sciences, Beijing, 100049, China;
    e College of Life and Sciences, Shanghai Normal University, Shanghai, 201602, China;
    f Life Science and Technology College, Harbin Normal University, Harbin, Heilongjiang 150025, China;
    g Drug and Cosmetics Excellence Center, School of Pharmacy, Walailak University, Nakhon Si Thammarat, 80160, Thailand
  • Received:2021-03-24 Revised:2021-08-12 Online:2022-05-25 Published:2022-06-21
  • Contact: Yue-Hong Yan,E-mail:yhyan@sibs.ac.cn
  • Supported by:
    This research was funded by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA19050404) and National Natural Science Foundation of China (No. 31800174).

Abstract: Lycophytes are an ancient clade of the non-flowering vascular plants with chromosome numbers that vary from tens to hundreds. They are an excellent study system for examining whole-genome duplications (WGDs), or polyploidization, in spore-dispersed vascular plants. However, a lack of genome sequence data limits the reliable detection of very ancient WGDs, small-scale duplications (SSDs), and recent WGDs. Here, we integrated phylogenomic analysis and the distribution of synonymous substitutions per synonymous sites (Ks) of the transcriptomes of 13 species of lycophytes to identify, locate, and date multiple WGDs in the lycophyte family Lycopodiaceae. Additionally, we examined the genus Phlegmariurus for signs of genetic discordance, which can provide valuable insight into the underlying causes of such conflict (e.g., hybridization, incomplete lineage sorting, or horizontal gene transfer).We found strong evidence that two WGD events occurred along the phylogenetic backbone of Lycopodiaceae, with one occurring in the common ancestor of extant Phlegmariurus (Lycopodiaceae) approximately 22–23 million years ago (Mya) and the other occurring in the common ancestor of Lycopodiaceae around 206–214 Mya. Interestingly, we found significant genetic discordance in the genus Phlegmariurus, indicating that the genus has a complex evolutionary history. This study provides molecular evidence for multiple WGDs in Lycopodiaceae and offers phylogenetic clues to the evolutionary history of Lycopodiaceae.

Key words: Lycophytes, Whole genome duplication, Polyploidization, Phylogenomics, Gene tree conflict