ABSTRACT
italic>Gentiana section Cruciata (Gentianaceae) is a medicinally important section of herbs, including Chinese traditional medicine Gentianae Macrophyllae Radix and Tibetan herb Jieji. Here, we assess the taxonomic significance using mtDNA nad1/b-c and nad5/d-e sequence data. A total of 144 nad1/b-c and nad5/d-e sequences from 11 species within Gentianaceae were obtained, including 138 sequences from 10 species within Gentiana section Cruciata and 6 sequences from Halenia elliptica (outgroup). The results showed that mtDNA nad1/b-c has species- level resolution within the section of Cruciata, i.e. the variable in the position 45 “C” could be used as a stable marker locus to distinguish G. robusta from other taxa; the variable in the position 352 and 353 “GA” could distinguish G. crassicaulis and G. tibetica from other taxa within the section. Intraspecies genotype variability was detected in nad1/b-c sequences of G. officinalis and G. siphonantha, respectively. These genotypes could be used as potential DNA barcode. In addition, intraspecies genotype variability was detected in nad5/d-e sequences of G. macrophylla, G. officinalis and G. siphonantha, respectively. Based on the stable marker locus, a species-specific PCR protocol was developed using the primer PF to identifying G. robusta in the section. This study could expand the understanding of the diversity of mtDNA nad1/b-c and nad5/d-e in the genus Gentiana, and provide the essence for the species identification within Gentiana section Cruciata.
ABSTRACT
Located in the transition zone between the Qinghai-Tibet Plateau and the Loess Plateau, Gansu province is one of the distribution centers of Sect. Cruciata, Gentiana (Gentianaceae) in China. Six species in the section, G. crassicaulis, G. straminea, G. siphonantha, G. officinalis, G. dahurica and G. macrophylla, are native to Gansu. In this paper, samples of 6 species and Halenia elliptica (outgroup) were collected. Nuclear DNA ITS, chloroplast DNA matK, rbcL, rpoC1, trnL (UAA) intron, psbA-trnH, atpB-rbcL, trnS (GCU)-trnG (UCC), rpl20-rps12 and trnL (UAA)-trnF (GAA) were sequenced from these samples. Based on the sequence analyses, high intragenomic polymorphisms were detected in ITS regions of G. crassicaulis, G. straminea, G. siphonantha, G. officinalis and G. dahurica, and they showed incomplete concerted evolution. A methodological study to identifying such close-related species as G. macrophylla, G. officinalis and G. dahurica was carried out based on the special genotypes. The results showed that 7 cp DNA sequence fragments could be used to identify G. crassicaulis, G. straminea and G. siphonantha. With nr ITS genotype II, III and IV of G. dahurica, the species can be distinguished from the close-related G. officinalis using 12 cloned sequences in a sample (with statistical significance). The cp DNA sequences of G. macrophylla were classified into two genotypes, and with genotype II, the species can be distinguished from the close-related G. officinalis and G. dahurica using 6 test samples each (with statistical significance). Furthermore, DNA barcode sequences were determined for all 6 species in Gansu. Also, the studies provide some basic data for analyses of genetic diversity and identification of Gentiana species.