Comparative analysis of complete chloroplast genome of ethnodrug Aconitum episcopale and insight into its phylogenetic relationships

Aconitum episcopale Leveille is an important medicinal plant from the genus Aconitum L. of Ranunculaceae family and has been used as conventional medicine in Bai, Yi, and other ethnic groups of China. According to the available data and Ethno folk applications, A. episcopale is the only Aconitum species that has detoxifying and antialcoholic property. It can detoxify opium, especially the poisoning of Aconitum plants. Aconitum species have been widely used for their medicinal properties, and it is important to be noted that many of the species of this plant are reported to be toxic also. Distinguishing the species of this plant based on the morphology is a tough task and there are also no significant differences in the chemical composition. Therefore, before application of this plant for medicinal usage, it is very important to identify the species which could be life-threatening and exclude them. In this paper, the complete chloroplast (cp) genome sequence of A. episcopale was acquired by Illumina paired-end (PE) sequencing technology and compared with other species in the same family and genus. Herein, we report the complete cp genome of A. episcopale. The whole circular cp genome of A. episcopale has been found to be of 155,827 bp in size and contains a large single-copy region (LSC) of 86,452 bp, a small single-copy region (SSC) of 16,939 bp, and two inverted repeat regions (IRs) of 26,218 bp. The A. episcopale cp genome was found to be comprised of 132 genes, including 85 protein-coding genes (PCGs), 37 transfer RNA genes (tRNAs), eight ribosomal RNA genes (rRNAs), and two pseudogenes. A total of 20 genes contained introns, of which 14 genes contained a single intron and two genes had two introns. The chloroplast genome of A. episcopale contained 64 codons encoding 20 amino acids, with the number of codons encoding corresponding amino acids ranging from 22 to 1068. The Met and Trp amino acids have only one codon, and other amino acids had 2–6 codons. A total of 64 simple sequence repeats (SSRs) were identified, among which mononucleotide sequences accounted for the most. Phylogenetic analysis showed that A. episcopale is closely related with A. delavayi. Cumulatively the results of this study provided an essential theoretical basis for the molecular identification and phylogeny of A. episcopale.