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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (2): 72-81.doi: 10.11707/j.1001-7488.20210208

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Phylogenomic Analysis of Rhododendron Species in Guizhou Baili Rhododendron Reserve Based on RAD Sequencing

Chengling Huang1,Gang Yao2,Xiaoling Tian3,Yongquan Ren1,Jiayong Huang4,Yongpeng Ma2,*   

  1. 1. College of Eco-Environment Engineering, Guizhou Minzu University Guiyang 550025
    2. Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations Kunming Institute of Botany, Chinese Academy of Sciences Kunming 650201
    3. College of Humanities and Sciences, Guizhou Minzu University Guiyang 550025
    4. Guizhou Baili-Rhododendron Scientific Research Institute Bijie 551614
  • Received:2020-03-23 Online:2021-02-25 Published:2021-03-29
  • Contact: Yongpeng Ma

Abstract:

Objective: Accurate species definition is the premise for development and utilization of wild plant resources. Due to the fact that chloroplast DNA fragments cannot distinguish Rhododendron species of the Baili Rhododendron Reserve in Guizhou reported before, the present study attempted to explore the phylogenetic relationships of Rhododendron in this region based on genome-level RAD(restriction-site associated DNA) sequencing technology, aiming to detect the power of RAD for species definition of complicated plant groups. Method: RAD-seq sequencing was performed on 34 species of Rhododendron from the reserve, and the basic characteristics of the data such as depth, coverage and polymorphic sites were evaluated. De novo method was employed to call SNPs which were subsequently evaluated to be neutral or selective by Tajima's D. Based on these neutral SNPs, fastStructure, PCA, GCTA and IQ-Tree software were finally employed to perform genetic separation, clustering and phylogenetic tree construction. Result: A total of 42 083 SNPs were obtained, among which 28 983 SNPs were detected to be neutral. The analyses of PCA, fastStructure and phylogenetic tree supports the morphological classification of 34 species of Rhododendron at the subgenus level. Subgen. Hymenanthes, Subgen. Azaleastrum, Subgen. Pentanthera and Subgen. Tsutsusi of the 6 subgenera can be distinguished, whereas Subgen. Pseudorhodorastrum and Subgen. Rhododendron cannot, suggesting that the 2 subgenera are closely related. In addition, at species-level most species can be distinguished, indicating a great improvement compared to previous studies, but the species with very similar morphological characteristics are indistinguishable, such as R. floribundum and R. denudatum. Conclusion: RAD-seq data produced a large number of SNPs that can distinguish most Rhododendron species in the reserve at the subgenus and species levels, proving that RAD technology had significant advantages over traditional molecular markers in the classification of complicated plant groups.

Key words: RAD-seq, Rhododendron, Baili Rhododendron Reserve, SNPs, phylogenetic classification

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