Characteristics of the complete chloroplast genome of Swertia divaricata Harry Sm. (Gentianaceae) and its phylogenetic inference

Abstract

Swertia divaricata Harry Sm., 1965, (Gentianaceae) is a perennial herb endemic to Northwest Yunnan, China, belonging to the species-rich genus Swertia . It possesses unique morphological features but its systematic position remains uncertain. To determine its phylogenetic placement, the complete plastid genome of S. divaricata was assembled utilizing high-throughput sequencing data. The genome is circular, spanning 152,073 bp, and comprises a large single-copy (LSC) region of 82,470 bp, a small single-copy (SSC) region of 18,153 bp, and two inverted repeats (IR) regions, each 25,725 bp. A total of 130 genes were annotated, including 85 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The plastome of S. divaricata exhibits a structure and gene composition highly similar to those of other Swertia plastomes. Phylogenetic analysis indicated that S. divaricata is closely related to S. erythrosticta , sister to a subclade comprising species from sections Swertia and Apterae . The plastome sequence described herein constitutes a valuable contribution to phylogenetic and evolutionary research on Swertia .