Phylogeny and Comparative Analysis of Chinese <i>Chamaesium</i> Species Revealed by the Complete Plastid Genome
2020
Xian-Lin Guo | Hong-Yi Zheng | Megan Price | Song-Dong Zhou | Xing-Jin He
<i>Chamaesium</i> H. Wolff (Apiaceae, Apioideae) is a small genus mainly distributed in the Hengduan Mountains and the Himalayas. Ten species of <i>Chamaesium</i> have been described and nine species are distributed in China. Recent advances in molecular phylogenetics have revolutionized our understanding of Chinese <i>Chamaesium</i> taxonomy and evolution. However, an accurate phylogenetic relationship in <i>Chamaesium</i> based on the second-generation sequencing technology remains poorly understood. Here, we newly assembled nine plastid genomes from the nine Chinese <i>Chamaesium</i> species and combined these genomes with eight other species from five genera to perform a phylogenic analysis by maximum likelihood (ML) using the complete plastid genome and analyzed genome structure, GC content, species pairwise Ka/Ks ratios and the simple sequence repeat (SSR) component. We found that the nine species’ plastid genomes ranged from 152,703 bp (<i>C. thalictrifolium</i>) to 155,712 bp (<i>C. mallaeanum</i>), and contained 133 genes, 34 SSR types and 585 SSR loci. We also found 20,953–21,115 codons from 53 coding sequence (CDS) regions, 38.4–38.7% GC content of the total genome and low Ka/Ks (0.27–0.43) ratios of 53 aligned CDS. These results will facilitate our further understanding of the evolution of the genus <i>Chamaesium</i>.
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