Complete chloroplast genome of Gentianopsis barbata and comparative analysis with related species from Gentianaceae

Gentianopsis barbata is an essential medicinal plant in China with high ornamental and medicinal values. Unfortunately, the study of the chloroplast genome of this plant still has a gap. This study sequenced and characterized the complete chloroplast genome of G. barbata. The complete chloroplast genome of G. barbata is a typical circular structure of 151 123 bp. It consists of a large single-copy region (82 690 bp) and a small single-copy region (17 887 bp) separated by a pair of inverted repeats (25 273 bp), which covers 78 protein-coding genes, 30 tRNAs, and 4 rRNAs. The long repeat sequence analysis showed that the P-type (palindromic) sequences were the major long repeat sequences. Thirty-seven simple sequence repeats were identified, most of which were single nucleotides. The Bayesian inference tree, maximum likelihood tree, and neighbor-joining tree suggested that G. barbata is grouped with Gentianopsis grandis and Gentianopsis paludosa. The divergence time analysis showed that G. barbata diverged at 1.243 Mya. Comparative analysis of chloroplast genomes can reveal interspecific diversity, and regions with high variation can be used to develop molecular markers applicable to various research areas. Our results provide a new insight into plastome evolution and a valuable resource for further studies on G. barbata.