J Syst Evol ›› 2025, Vol. 63 ›› Issue (2): 245-267.DOI: 10.1111/jse.13130  cstr: 32099.14.jse.13130

• Research Article • Previous Articles     Next Articles

Chromosome-level genome assembly of a rare karst-growing Rhododendron species provides insights into its evolution and environmental adaptation

Sulin Wen1,2, Xiaowei Cai1, Kun Yang1, Yi Hong1, Fuhua Fan3, Qian Wang1, Bingxue Zhang4, Qiandong Hou1, Yuxing Leng1, Guang Qiao1*, Xiaopeng Wen1*, and Xiaohui Shen2*   

  1. 1Key Laboratory of Mountain Plant Resources Protection and Germplasm Innovation (Ministry of Education), Institute of Agro‐bioengineering/College of Life Sciences, Guizhou University, Guiyang 550025, China
    2School of Design, Shanghai Jiao Tong University, Shanghai 200240, China
    3Institute for Forest Resources and Environment of Guizhou, Guizhou University, Guiyang 550025, China
    4Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences and Medicine, Zhejiang Sci‐Tech University, Hangzhou 310018, China

    *Authors for correspondence. Guang Qiao. E‐mail: gqiao@gzu.edu.cn; Xiaopeng Wen. E‐mail: xpwensc@hotmail.com; Xiaohui Shen. E‐mail: shenxh62@sjtu.edu.cn
  • Received:2024-02-25 Accepted:2024-05-27 Online:2024-09-29 Published:2025-03-01
  • Supported by:
    We gratefully acknowledge the financial support for this project by the Special Programme for Seed Engineering of the Guizhou Department of Agriculture and Rural Area (2022‐2023), the Innovation Talent Programme of Guizhou Province (2016‐4010), the National Guidance of Local Science and Technology Development Fund of China (2023)009, as well as the Guizhou Provincial Science and Technology Projects of China (YQK [2023]008).

Abstract: Rhododendron is a significant plant genus, with over 600 identified species in China. The subgenus Hymenanthes holds the largest number of Rhododendron germplasms and showcases strong environmental adaptability. However, there remains a lack of understanding regarding Rhododendron's evolution and environmental adaptations. Rhododendron bailiense Y.P.Ma, C.Q.Zhang & D.F.Chamb., an exceedingly rare species, thrives in the alkaline karst landforms of Guizhou, southwest China, different from the typical growing environment of other Rhododendron species. In this study, we present a chromosome-level genome assembly of R. bailiense, revealing a genome size of 923.3 Mb, a contig N50 of 24.5 Mb, and a total of 47 567 predicted genes. An evolutionary analysis indicated that R. bailiense diverged from its ancestors prior to the other subgenus Hymenanthes rhododendrons, with the expanded and contracted genes being notably enriched in “stress response” and “growth,” respectively. Rhododendron bailiense is predominantly found on limestone soil in the mountains of Guizhou, with only two wild populations known. The genome of R. bailiense contained a high copy number of ankyrin repeat (ANK) and Ca2+-ATPase (CAP) genes, primarily involved in Ca2+ transport, shedding light on how R. bailiense copes with karst high-calcium stress. In contrast, the structures of the ANKs displayed unique characteristics, while the CAPs showed conservatism. The R. bailiense genome provides new insights into the adaptation and evolutionary history of Rhododendron plants in karst environments, potentially offering valuable information for adaptive breeding and ecological enhancement in such challenging settings.

Key words: adaptive evolution, ankyrin repeats protein, Ca2+‐ATPase, karst, Rhododendron bailiense.