Phylogenetic and mutation point analysis of DNA barcoding sequences in Solanum nigrum / 中草药

Objective: In this study, phylogenetic analysis was used to compare the ITSs and trnH-psbA sequences of 17 Solanum nigrum samples, providing the theoretic foundation to utilize their resources and evaluate their genuineness. Methods: PCR method was used to amplify the region of ITS and trnH-psbA, and the seqeucens of ITS1 + ITS2 and trnH-psbA were obtained after the amplified fragment sequences were blasted in NCBI database. The Neighbor joining (NJ) and maximum parsimony (MP) method were used to construct phylogenetic trees and Kimura two-parameter (K2-P) model was used to calculate the genetic distance of different samples. Clustal X and DNAman softwares were applied for multi-alignment of ITS1, ITS2, and trnH-psbA sequences from different samples. Results: The lengths of ITS1 and ITS2 sequences from 17 samples were 230 and 206 bp, respectively, and trnH-psbA sequences were 446 or 447 bp. ITS1, ITS2, and trnH-psbA had seven, two, and three mutation points, respectively. These 17 samples were clustered to three latitude-dependent groups based on both ITS1 + ITS2 and trnH-psbA sequences. Conclusion: Phylogenetic and mutation point analysis will provide the theoretic foundation to utilize the resources of Chinese S. nigrum, investigate their evolution, and evaluate their genuineness. The results of mutation point will also be used in the identification of related S. nigrum resources.

Identification of plants in Mussaenda L. based on DNA barcoding / 中草药

This study aims at developing fast and accurate species identification methods for the plants of Mussaenda L. In the present study, DNA barcoding analysis was carried out on 89 individuals representing 20 species of Mussaenda in order to evaluate the performance of the four candidate barcoding loci (matK, rbcL, trnH-psbA, and ITS) and ITS2 region. Based on sequence similarity and Neighbor-joining (NJ) tree reconstruction, we detected inter-and intra-specific genetic distances using Kimura 2-parameter (K2P). Inter-specific genetic distance of species in Mussaenda was significantly higher than intra-specific genetic distance. The region of ITS2 showed the highest discrimination power among the independent sequences. Comparably high species discrimination power was also revealed by the matK and ITS data set. The candidate barcode of rbcL displayed the lowest identification rate among the others. However, each individual candidate barcode demonstrated significantly lower discrimination power than the barcode of combined data set. Comparable discrimination power was revealed between the two barcodes of combined sequences matK + rbcL + ITS and matK + rbcL + trnH-psbA + ITS, which showed the values around 77% and 75% based on sequence similarity and NJ tree method. Totally 15 species were identified based on NJ analysis of matK + rbcL + ITS. Consequently, the combined sequence of matK + rbcL + ITS provides an effective and fast tool for the identification and authentication of medicinal plant species in the genus Mussaenda L.