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

• Published in: Journal of integrative plant biology 2023-06, Vol.65 (6), p.1490-1504
• Main Authors: Chen, Chunlin, Ruhfel, Brad R., Li, Jialiang, Wang, Zefu, Zhang, Lushui, Zhang, Lei, Mao, Xingxing, Wang, Ji, He, Dashan, Luo, Yue, Hu, Quanjun, Duan, Yuanwen, Xu, Xiaoting, Xi, Zhenxiang, Liu, Jianquan
• Format: Article
• Language: English
• Subjects: ancient hybridization; Biodiversity; floral diversity; Flowers; Genera; Genomes; Gentianaceae; Phylogenetics; phylogenomics; Phylogeny; Qinghai–Tibet Plateau; Species diversity; Stigmas (botany); subtribe Swertiinae
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.13464

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. Sampling of 60 species from all 15 recognized genera in the subtribe Swertiinae and construction of well‐resolved backbone relationships of the subtribe based phylotranscriptomics revealed that key floral traits were randomly distributed in phylogenies and the likely ancient hybrid origin of a clade with diverse floral morphology.