Comparative and phylogenetic analyses of Swertia L. (Gentianaceae) medicinal plants (from Qinghai, China) based on complete chloroplast genomes.

Xin Xu,Shixia Wei,Hongyu Wang,Zhen Wei,Ran Chu,Kexin Song,Yuhua Shi,Jinping Li,Mengjie Luan,Shixin Zhu

doi:10.1590/1678-4685-gmb-2021-0092

Xin Xu, Shixia Wei + Show 8 more

Open Access

https://doi.org/10.1590/1678-4685-gmb-2021-0092

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Abstract

Swertia L. is a large genus in Swertiinae (Gentianaceae). In China, many Swertia species are used as traditional Tibetan medicines, known as “Zangyinchen” or “Dida”. However, the phylogenetic relationships among Swertia medicinal plants and their wild relatives have remained unclear. In this study, we sequenced and assembled 16 complete chloroplast (cp) genomes of 10 Swertia species, mainly distributed in Qinghai Province, China. The results showed that these species have typical structures and characteristics of plant cp genomes. The sizes of Swertia cp genomes are ranging from 149,488 bp to 154,097 bp. Most Swertia cp genomes presented 134 genes, including 85 protein coding genes, eight rRNA genes, 37 tRNA genes, and four pseudogenes. Furthermore, the GC contents and boundaries of cp genomes are similar among Swertia species. The phylogenetic analyses indicated that Swertia is a complex polyphyletic group. In addition, positive selection was found in psaI and petL genes, indicating the possible adaptation of Qinghai Swertia species to the light environment of the Qinghai-Tibet plateau. These new cp genome data could be further investigated to develop DNA barcodes for Swertia medicinal plants and for additional systematic studies of Swertia and Swertiinae species.

Highlights

Swertia L., a large genus of plants in Swertiinae (Gentianaceae) with about 170 species, are mainly distributed in Asia, Africa, North America and Europe (Ho et al, 1994)
Some Swertia species are often used as Tibetan medicines, known as ‘Zangyinchen’ or ‘Dida’ to treat hepatobiliary diseases (Zhong et al, 2009)
Gene deletion and additional pseudogenes were found in some Swertia cp genomes, as results of additional termination codons, complete or partial gene loss (Table S5)

Summary

Introduction

Swertia L., a large genus of plants in Swertiinae (Gentianaceae) with about 170 species, are mainly distributed in Asia, Africa, North America and Europe (Ho et al, 1994). We assembled and annotated the complete chloroplast (cp) genomes of 16 Swertia taxa (10 Swertia species) mainly distributed in Qinghai province, China. The chloroplast genomes of these Swertia species were compared and used to study the phylogenetic relationships and selection pressure.

Results

Conclusion