J Integr Plant Biol.

• Research Article •    

Phylotranscriptomics of Swertiinae (Gentianaceae) reveals that key floral traits are not phylogenetically correlated

Chunlin Chen1†, Brad R. Ruhfel2†, Jialiang Li1, Zefu Wang1, Lushui Zhang1, Lei Zhang1, Xingxing Mao1, Ji Wang1, Dashan He1, Yue Luo1, Quanjun Hu1, Yuanwen Duan3, Xiaoting Xu1*, Zhenxiang Xi1* and Jianquan Liu1*   

  1. 1. Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education & State Key Laboratory of Hydraulics and Mountain River Engineering, College of Life Sciences, Sichuan University, Chengdu 610065, China
    2. Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
    3. Institute Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
    These authors contributed equally to this work.
    *Correspondences: Xiaoting Xu (xiaotingxu@scu.edu.cn); Zhenxiang Xi (zxi@scu.edu.cn); Jianquan Liu (liujq@nwipb.ac.cn, Dr. Liu is fully responsible for the distributions of the materials associated with this article)
  • Received:2022-09-25 Accepted:2023-02-06 Online:2023-03-24

Abstract: Establishing how lineages with similar traits are phylogenetically related remains critical for understanding the origin of biodiversity on Earth. Floral traits in plants are widely used to explore phylogenetic relationships and to delineate taxonomic groups. The subtribe Swertiinae (Gentianaceae) comprises more than 350 species with high floral diversity ranging from rotate to tubular corollas and possessing diverse nectaries. Here we performed phylogenetic analysis of 60 species from all 15 genera of the subtribe Swertiinae sensu Ho and Liu, representing the range of floral diversity, using data from the nuclear and plastid genomes. Extensive topological conflicts were present between the nuclear and plastome trees. Three of the 15 genera represented by multiple species are polyphyletic in both trees. Key floral traits including corolla type, absence or presence of lobe scales, nectary type, nectary position, and stigma type are randomly distributed in the nuclear and plastome trees without phylogenetic correlation. We also revealed the likely ancient hybrid origin of one large clade comprising 10 genera with diverse floral traits. These results highlight the complex evolutionary history of this subtribe. The phylogenies constructed here provide a basic framework for further exploring the ecological and genetic mechanisms underlying both species diversification and floral diversity.

Key words: ancient hybridization, floral diversity, Gentianaceae, phylogenomics, Qinghai-Tibet Plateau, subtribe Swertiinae

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