Plant Diversity ›› 2021, Vol. 43 ›› Issue (06): 472-479.DOI: 10.1016/j.pld.2021.05.005

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Genetic diversity and structure of Rhododendron meddianum, a plant species with extremely small populations

Xiu-Jiao Zhanga,b,d, Xiong-Fang Liua, De-Tuan Liuc, Yu-Rong Caoa,b, Zheng-Hong Lia, Yong-Peng Mac, Hong Maa   

  1. a Research Institute of Resources Insects, Chinese Academy of Forestry, Kunming, 650224, Yunnan, China;
    b College of Forestry, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China;
    c Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China;
    d Yunnan Key Laboratory of Plant Reproductive Adaption and Evolutionary Ecology, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, Yunnan, China
  • Received:2020-12-15 Revised:2021-05-25 Online:2021-12-25 Published:2022-01-11
  • Contact: Yong-Peng Ma, Hong Ma
  • Supported by:
    This work was supported by the Fundamental Research Funds for the Central Non-profit Research Institution of the Chinese Academy of Forestry (Grant No. CAFYBB2019ZB007); the Biodiversity Survey and Assessment Project of the Ministry of Ecology and Environment, China (Grant No. 2019HJ2096001006); the Ten Thousand Talent Program of Yunnan Province (Grant No. YNWRQNBJ-2019-010; YNWR-QNBJ-2018-174); and the Young and Middle-aged Academic and Technical Leader Reserve Talent Project of Yunnan Province (Grant No. 2018HB066).

Abstract: Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations. In this study, we used double digest restriction-siteassociated DNA sequencing (ddRAD) technology to assess the genetic diversity, genetic structure and demographic history of the three extant populations of R. meddianum. Analysis of SNPs indicated that R. meddianum populations have a high genetic diversity (π=0.0772 ±0.0024, HE=0.0742 ±0.002). Both FST values (0.1582-0.2388) and AMOVA showed a moderate genetic differentiation among the R. meddianum populations. Meanwhile, STRUCTURE, PCoA and NJ trees indicated that the R. meddianum samples were clustered into three distinct genetic groups. Using the stairway plot, we found that R. meddianum underwent a population bottleneck about 70,000 years ago. Furthermore, demographic models of R. meddianum and its relative, Rhododendron cyanocarpum, revealed that these species diverged about 3.05 (2.21-5.03) million years ago. This divergence may have been caused by environmental changes that occurred after the late Pliocene, e.g., the Asian winter monsoon intensified, leading to a drier climate. Based on these findings, we recommend that R. meddianum be conserved through in situ, ex situ approaches and that its seeds be collected for germplasm.

Key words: Rhododendron meddianum, ddRAD, Genetic diversity, Population demography, Conservation implications