Hyeyeon KimP, Ji-Eun Park, Jae-Ein Choi, Yoo-Jung Park, Halam Kang, Kyeong-Sik CheonC

Department of Biological Science, Sangji University, Wonju, Korea

Tripterospermum japonicum is a perennial climbing plant belonging to the genus Tripterospermum (Gentianaceae), distributed in Korea and Japan. In Korea, it is restricted to montane edges of Ulleungdo and Jejudo Islands. T. japonicum is considered a species of high conservation value due to its restricted geographic distribution. Additionally, pharmacological studies have reported the presence of bioactive compounds in its aerial parts, demonstrating its significant value as a medicinal plant resource. This study aimed to decode the chloroplast genome of Japanese T. japonicum and perform comparative analysis with previously reported Korean individuals. The complete chloroplast genome sequence of T. japonicum was 151,266 bp in length, with LSC, SSC, and IR regions measuring 82,511 bp, 17,589 bp, and 25,583 bp, respectively. A total of 112 genes were identified, including 78 protein-coding genes, 30 tRNAs, and 4 rRNAs. Comparative analysis of chloroplast genomes between Korean and Japanese individuals revealed sequence differences of 1 bp in the trnR-ACG gene and 17 bp in the ycf1 gene, while all other regions were identical. Maximum likelihood phylogenetic analysis showed that the genus Tripterospermum formed a strongly supported monophyletic group, with T. japonicum positioned as a sister group to T. nienkui, T. filicaule, and T. membranaceum. This study elucidates the chloroplast genome structure and intraspecific genetic variation of T. japonicum, providing fundamental data for phylogenetic studies of the genus Tripterospermum and biogeographic research of East Asian populations.