Biodiv Sci ›› 2021, Vol. 29 ›› Issue (6): 722-734.DOI: 10.17520/biods.2020484

• Original Papers:Plant Diversity • Previous Articles     Next Articles

Dating whole-genome duplication reveals the evolutionary retardation of Angiopteris

Ting Wang1,2,3, Zengqiang Xia1,2,4, Jiangping Shu1,2,5, Jiao Zhang4, Meina Wang1,2, Jianbing Chen1,2, Kanglin Wang6, Jianying Xiang7,*(), Yuehong Yan1,2,*()   

  1. 1 The Orchid Conservation and Research Centre of Shenzhen, Shenzhen, Guangdong 518114
    2 Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, Shenzhen, Guangdong 518114
    3 College of Biodiversity Conservation, Southwest Forestry University, Kunming 650224
    4 CAS Center for Excellence in Molecular Plant Sciences/Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032
    5 South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650
    6 Green Development Institute, Southwest Forestry University, Kunming 650224
    7 Yunnan Academy of Biodiversity, Southwest Forestry University, Kunming 650224
  • Received:2020-12-29 Accepted:2021-04-14 Online:2021-06-20 Published:2021-04-22
  • Contact: Jianying Xiang,Yuehong Yan

Abstract:

Aim: Whole-genome duplication (WGD) plays a positive role in speciation in vascular plants and is considered to be an important mechanism for species adaptation to the extreme environments. Dating whole-genome duplication events in different species is essential for understanding the adaptive evolution of organisms. However, the role that these mechanisms play in vascular plants, especially ferns, is still poorly understood.

Method: Based on the synonymous substitution rates (Ks) and absolute dating of the WGD event, this study used three different transcriptome sequences of Angiopteris fokiensis to analyze the contribution of polyploidy to the evolution of plants, and the silent substitution rate. Gene annotation and functional enrichment were carried out to elucidate the biological processes, molecular function, and cellular component for the genes retained after the WGD.

Results: We found that there was at least one WGD event in A. fokiensis at 159-165 Mya, and most duplicated genes were often related to nutrient metabolism, signal transduction, adaptive regulation and anatomical structure development. The silent substitution rate of A. fokiensis is 1.66 × 10‒9 synonymous substitutions per site per year. Based on the above results, we speculate that the WGD event was associated with gymnosperms flourishing and the emergence of core angiosperms, or the Toarcian extinction event. The retention of particular genes after the WGD may have promoted genetic and morphological innovation in Angiopteris, thus helping it adapt to the drastic changes in environmental conditions. At present, A. fokiensisis the slowest evolving group of land plants except gymnosperms, which may relate to the long generation time, large genome and stable living habitat.

Conclusion: In this study, we analyzed the whole-genome duplication history and the patterns of retention of duplicated genes in A. fokiensis, suggesting that WGD events are of great influence in promoting the adaptation to extreme environmental changes of plants with slower evolutionary rates. These results provide more inspiration for understanding the adaptive evolution of other land plants.

Key words: polyploidization, adaptive evolution, evolution rate, ferns, transcriptome