Phylogenetic and mutation point analysis of DNA barcoding sequences in Polygonatum cyrtonema / 中草药

ABSTRACT

Objective: In this work, phylogenetic analysis was used to compare the ITS2 and psbA-trnH sequences of Polygonatum cyrtonema samples from different geographical sources, so as to explore the genetic diversity and genetic relationship of these resources. Methods: PCR method was used to amplify the regions of ITS and psbA-trnH, and the sequences of ITS2 and psbA-trnH were obtained after the amplified fragment sequences were blasted in NCBI database. The neighbor joining (NJ) and maximum parsimony (MP) methods were used to construct phylogenetic trees and Kimura two-parameter (K2-P) model was used to calculate the genetic distance of different samples. Mega and DNAman softwares were applied for mutiple alignment of ITS2 and psbA-trnH sequences of 25 samples of P. cyrtonema. Results: The lengths of ITS2 and psbA-trnH sequences of Anhui Qingyang and Fujian Taining samples of P. cyrtonema were 224 bp and 620 bp, respectively. The lengths of ITS2 and psbA-trnH of the remaining 24 samples were 225 bp and 621 bp, respectively. ITS2 and psbA-trnH had seven and four mutation points, respectively. These 25 samples were clustered into two groups based on ITS2 sequences. Five samples in Hunan and Guizhou were clustered into one group, while the other 20 samples were clustered into another group. The genetic distance showed that the samples from Huaxi and Jianhe in Guizhou Province and Jianyang in Fujian Province had the largest genetic distance. Phylogenetic tree constructed by psbA-trnH sequences were unable to distinguish 25 samples from different geographical sources. Conclusion: Phylogenetic and mutation analysis will provide the theoretic foundation to utilize the resources of P. cyrtonema, investigate their evolution, and evaluate their genuineness. The results of mutation point will also be used in the identification of related P. cyrtonema resources.