The complete chloroplast genome of Japanese <i>Tripterospermum japonicum</i> (Gentianaceae) reveals extremely low intraspecific variation from a Korean individual

<i>Tripterospermum japonicum</i> (Gentianaceae) is a twining perennial herb distributed in Korea and Japan, with a restricted, disjunct distribution in both countries that gives it high conservation value. Although the complete chloroplast genome of a Korean individual has previously been reported, the cp genome of Japanese individuals has remained unknown. This study aimed to determine the cp genome of a Japanese individual of <i>T. japonicum</i> for the first time and to characterize its genomic features and intraspecific variation by comparing it with a Korean individual. The results revealed that the cp genome of the Japanese individual is 151,266 bp in length, with a GC content of 37.8%. It consists of a large singlecopy region of 82,513 bp, a small single-copy region of 17,589 bp, and two inverted repeat regions of 25,581 bp each. It contains 112 unique genes, including 78 protein-coding genes, 30 transfer RNA genes, and four ribosomal RNA genes. Comparison with the Korean individual revealed a highly conserved genome structure, differing by only three InDels. A phylogenetic analysis confirmed a close relationship between the two individuals within the genus <i>Tripterospermum.</i>