DNA super-barcoding of several medicinal species in Gentiana from Yunnan province / 中国中药杂志

Gentiana is an important but complicated group in Gentianaceae. The genus covers numerous medicinal plants which are difficult to be identified. In the present study, several medicinal species in Gentiana from Yunnan province, including G. rigescens, G.rhodantha, and G. delavayi, were sequenced using the Illumina HiSeq 2500 system. Three complete chloroplast genome sequences were obtained after assembly and annotation. According to several published genome sequences of G. crassicaulis, the DNA super-barcoding of species in Gentiana was preliminarily carried out. The results revealed that chloroplast genomes of the three species were conservative with short lengths(146 944, 148 992, and 148 796 bp, respectively). The genomes encoded 114 genes, including 78 protein-coding genes, 30 tRNA genes, 4 rRNA genes, and 2 pseudogenes. Furthermore, these medicinal species in Yunnan province were identified using DNA super-barcoding based on chloroplast genomes. The results showed that the Gentiana species could be gathered into monophyletic branches with a high support value(100%). It indicated that DNA super-barcoding possessed obvious advantages in discriminating species in complicated genera. This study is expected to provide a scientific basis for the identification, utilization, and conservation of Gentiana species.

Transcriptome analysis and validation of key genes involved in biosynthesis of iridoids in Gentiana lhassica / 中国中药杂志

As the main chemical constituents, iridoids are widely distributed within Gentiana, Gentianaceae, with promising bioactivities. Based on the previous work, the transcriptome of G. lhassica, an original plant of Tibetan herb "Jieji Nabao", was sequenced and analyzed in this study, and the transcriptome databases of roots, stems, leaves, and flowers were constructed so as to explore unigenes that may encode the key enzymes in the biosynthetic pathway of iridoids. Then, qRT-PCR was used to validate the relative expression levels of 11 genes named AACT, DXS, MCS, HDS, IDI, GPPS, GES, G10H, 7-DLNGT, 7-DLGT, and SLS in roots, stems, leaves, and flowers. Also, the total contents of gentiopicroside and loganic acid were determined by HPLC, respectively. The results are as follows:(1)a total of 76 486 unigenes with an average length of 852 bp were obtained;(2)335 unigenes were involved in 19 stan-dard secondary metabolism pathways in KEGG database, with phenylpropanoid biosynthesis having the maximum number(75 unigenes), and no isoflavone biosynthetic pathway was annotated;(3)171 unigenes participatedin 27 key enzymes encoding in the biosynthetic pathway of iridoids, and 1-deoxy-D-xylulose-5-phosphate reductoisomerase(DXR) gene was highly expressed;(4)qRT-PCR results were approximately consistent with RNA-Seq data and the relative expression levels of the 11 genes were higher in the aboveground parts(stem, leaf, and flower) than in the underground part(root);(5)the total contents of gentiopicroside and loganic acid were higher in the aboveground parts(stem, leaf, and flower) than in the underground part(root), and the difference was significant. This study provides basic scientific data for accurate species identification, evaluation of germplasm resources, research on secondary pro-duct accumulation of medicinal plants within Gentianaceae, and protection of endangered alpine species.