Résumé
The family Gentianaceae are found mostly on the Qinghai-Tibet Plateau in China, which have important medicinal properties. Based on 27 published complete chloroplast genome sequences from Gentiana, Swertia, Halenia, Menyanthes, and Nymphoides of Gentianaceae, the chloroplast genome structure was analyzed. The cp genome sizes of 27 taxa range from 137 to 154 kb, and they contain 101-114 unique genes, including 67-80 protein-coding genes, 30 tRNA genes and four rRNA genes. Also, a Bayesian phylogenetic tree was constructed based on the 27 cp genome sequences with Pentalinon luteum (Apocynaceae) as the outgroup. The tree was topologically consistent with the treatments of traditional taxonomy, and the cp genome sequences have genus- or section-level resolution. In addition, we reviewed the significance of species identification within the family. These cp genome sequences could provide basic data for the endangered species conservation, the genetic analysis and pharmacognostic researches of herbs from Gentianaceae.
Résumé
The circular double-stranded cpDNA sequence consists of two inverted repeat (IR) regions, a large single-copy region (LSC) and a small single-copy region (SSC). The function of some genes within the genome is clear. However, it is unknown for such chloroplast genes as hypothetical chloroplast reading frames (ycfs) and so on. As one of ycf s, ycf15 gene is located within IR regions with length of 250-550 bp, conserved among plants and also, its function is often unclear. The gene has attracted an intense attention during the past decade. This review presents an overview of ycf15 gene including its basic type, structural features, and the application to phylogenetic analyses. As a potential DNA marker for species identification, future implications of the gene are also introduced.