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

doi:10.1016/j.pld.2021.05.005

Abstract

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, H_E=0.0742 ±0.002). Both F_ST 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

Xiu-Jiao Zhang, Xiong-Fang Liu, De-Tuan Liu, Yu-Rong Cao, Zheng-Hong Li, Yong-Peng Ma, Hong Ma. Genetic diversity and structure of Rhododendron meddianum, a plant species with extremely small populations[J]. Plant Diversity, 2021, 43(06): 472-479.

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