The complete chloroplast genome of Tibetan folk medicinal plant Swertia franchetiana

Abstract

Asone of the original plants of traditional Tibetan folk medicinal ‘Zangyinchen’, Swertia franchetiana (S. franchetiana) was used to treat a variety of ailments. Large amount of fruiting harvesting has led to a sharp decrease and gradual depletion of its resources. As a result, the wild resource is on the verge of extinction, it needs urgent conservation. Here, we report the complete sequence of the chloroplast genome of S. franchetiana. The genome was 153,087 bp in length with 130 genes comprising 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The overall GC content of G. paludosa chloroplast genome was is 38.17%. Phylogenomic analysis suggested that S. franchetiana formed a clade with Swertia mussotii with high bootstrap values, indicating that the S. franchetiana was closely related to S. mussotii

Keywords:

• Swertia franchetiana
• chloroplast genome
• Gentianaceae

Swertia franchetiana (S. franchetiana), belonging to the family Gentianaceae, is one of original plants of traditional Tibetan folk medicinal species called ‘Zangyinchen’ (Yang 1991). It is mainly distributed in Qinghai, Xizang, Sichuan, and the south of Gansu with high altitude (2300–3800 m) (He et al. 1988). It is well known for the treatment of a variety of ailments, including bilious hepatitis, cholecystitis, hepatogenous jaundice, and hypoglycemia (Wang et al. 1994, 2005; Sun et al. 2009). Owing to its therapeutic activities against diseases, the resource demand of S. franchetiana has increased rapidly. In particular, large amount of fruiting harvesting has led to a sharp decrease and gradual depletion of its resources (Liu et al. 1996). As a result, its geographical distribution has become increasingly narrow, and the wild resource is on the verge of extinction. So far, the research of S. franchetiana has mainly focused on its chemical composition (Li et al. 2008; Liu et al. 2008; Sun et al. 2009; Li et al. 2017), cultivation (Chen et al. 2005), and mineral elements (Li et al. 2005). Therefore, it is beneficial to understand more genetic information about S. franchetiana to perform conservation, genetic improvement, and sustainable management for this risk species.

We collected a wild individual of S. franchetiana from Xinping village (101°37.556′E, 36°34.460′N, 2510 m), Huangzhong country in Qinghai province of China (Voucher specimen: QHGC20190821, HNWP). We used the following process to sequence the complete chloroplast genome of S. franchetiana: extraction of Genome DNA, fragmentation of DNA, construction of Illumina pair-end library, sequencing, assembling and annotation. The annotated genomic sequence had been submitted to GenBank with the accession number MT188728.

The total length of complete chloroplast genome of S. franchetiana is 153,087 bp, which consisted of a large single-copy region (LSC, 83,220 bp) a small single-copy region (SSC, 18,369 bp) and two inverted repeats (IR, 25,749 bp). The overall CC content is 38.17%. The chloroplast genome includes a total of 130 functional genes including 85 protein-coding genes, 37 tRNA, and 8 rRNA. A total of 18 genes were duplicated in the IR regions including seven tRNA, four rRNA, and seven protein-coding genes. The genome organization, gene/intron content and gene relative positions of the newly sequenced plastid genome were almost identical to other Gentianaceae species.

Phylogenetic tree was reconstructed using the complete chloroplast genomes of S. franchetiana and 18 other species from Gentianaceae, and Carissa macrocarpa (Apocynaceae) was used as an out-group. Maximum-likelihood (ML) analysis showed that S. franchetiana formed a clade with Swertia mussotii with high bootstrap values (Figure 1), indicating that the S. franchetiana was closely related to S. mussotii.

Figure 1. Maximum likelihood phylogenetic tree based on 20 complete chloroplast genome sequences.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by The Key R&D and Transformation Projects in Qinghai Province and The National Key Research and Development Program of China.