Find in Library

The <i>Tripterospermum</i>, comprising 34 species, is a genus of Gentianaceae. Members of <i>Tripterospermum</i> are mostly perennial, entwined herbs with high medicinal value and rich in iridoids, xanthones, flavonoids, and triterpenes. However, our inadequate understanding of the differences in the plastid genome sequences of <i>Tripterospermum</i> species has severely hindered the study of their evolution and phylogeny. Therefore, we first analyzed the 86 Gentianae plastid genomes to explore the phylogenetic relationships within the Gentianae subfamily where <i>Tripterospermum</i> is located. Then, we analyzed six plastid genomes of <i>Tripterospermum</i>, including two newly sequenced plastid genomes and four previously published plastid genomes, to explore the plastid genomes’ evolution and phylogenetic relationships in the genus <i>Tripterospermum</i>. The <i>Tripterospermum</i> plastomes have a quadripartite structure and are between 150,929 and 151,350 bp in size. The plastomes of <i>Tripterospermum</i> encoding 134 genes were detected, including 86 protein-coding genes (CDS), 37 transfer RNA (tRNA) genes, eight ribosomal RNA (rRNA) genes, and three pseudogenes (<i>infA</i>, <i>rps19</i>, and <i>ycf1</i>). The result of the comparison shows that the <i>Tripterospermum</i> plastomes are very conserved, with the total plastome GC content ranging from 37.70% to 37.79%. In repeat sequence analysis, the number of single nucleotide repeats (A/T) varies among the six <i>Tripterospermum</i> species, and the identified main long repeat types are forward and palindromic repeats. The degree of conservation is higher at the SC/IR boundary. The regions with the highest divergence in the CDS and the intergenic region (IGS) are <i>psaI</i> and <i>rrn4.5-rrn5</i>, respectively. The average pi of the CDS and the IGS are only 0.071% and 0.232%, respectively, indicating that the <i>Tripterospermum</i> plastomes are highly conserved. Phylogenetic analysis indicated that Gentianinae is divided into two clades, with <i>Tripterospermum</i> as a sister to <i>Sinogeniana</i>. Phylogenetic trees based on CDS and CDS + IGS combined matrices have strong support in <i>Tripterospermum</i>. These findings contribute to the elucidation of the plastid genome evolution of <i>Tripterospermum</i> and provide a foundation for further exploration and resource utilization within this genus.