title: Molecular identification of Uncaria (Gouteng) through DNA barcoding.
abstract: BACKGROUND
  While DNA barcoding is an important technology for the authentication of the botanical origins of Chinese medicines, the suitable markers for DNA barcoding of the genus Uncaria have not been reported yet. This study aims to determine suitable markers for DNA barcoding of the genus Uncaria (Gouteng).
  
  
  METHODS
  Genomic DNA was extracted from the freshly dried leaves of Uncaria plants by a Bioteke's Plant Genomic DNA Extraction Kit. Five candidate DNA barcode sites (ITS2, rbcL, psbA-trnH, ITS, and matK) were amplified by PCR with established primers. The purified PCR products were bidirectionally sequenced with appropriate amplification primers in an ABI-PRISM3730 instrument. The candidate DNA barcodes of 257 accessions of Uncaria in GenBank were aligned by ClustalW. Sequence assembly and consensus sequence generation were performed with CodonCode Aligner 3.7.1. The identification efficiency of the candidate DNA barcodes was evaluated with BLAST and nearest distance methods. The interspecific divergence and intraspecific variation were assessed by the Kimura 2-Parameter model. Genetic distances were computed with Molecular Evolutionary Genetics Analysis 6.0.
  
  
  RESULTS
  The accessions of the five candidate DNA barcodes from 11 of 12 species of Uncaria in China and four species from other countries were included in the analysis, while 54 of total accessions were submitted to GenBank. In a comparison of the interspecific genetic distances of the five candidate barcodes, psbA-trnH exhibited the highest interspecific divergence based on interspecific distance, theta prime, and minimum interspecific distance, followed by ITS2. The distribution of the interspecific distance of ITS2 and psbA-trnH was higher than the corresponding intraspecific distance. Additionally, psbA-trnH showed 95.9 % identification efficiency by both the BLAST and nearest distance methods regardless of species or genus level. ITS2 exhibited 92.2 % identification efficiency by the nearest distance method, but 87 % by the BLAST method.
  
  
  CONCLUSIONS
  While psbA-trnH and ITS2 (used alone) were applicable barcodes for species authentication of Uncaria, psbA-trnH was a more suitable barcode for authentication of Uncaria macrophylla.
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Key Laboratory of Biological Molecular Medicine Research of Guangxi Higher Education, 530021 Nanning, Guangxi China ; Clinical Laboratory, Maternal and Child Health Hospital of Guangxi, 530003 Nanning, Guangxi China.
authors: Yin-Lin
authors: YL
authors: Tang
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Key Laboratory of Biological Molecular Medicine Research of Guangxi Higher Education, 530021 Nanning, Guangxi China.
authors: Yao-Sheng
authors: YS
authors: Wu
authors: Guangxi Academy of Minority Nationality Medicine and Pharmacology, 530001 Nanning, Guangxi China.
authors: Rui-Song
authors: RS
authors: Huang
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Key Laboratory of Biological Molecular Medicine Research of Guangxi Higher Education, 530021 Nanning, Guangxi China.
authors: Nai-Xia
authors: NX
authors: Chao
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; School of Pharmacy, Guangdong Medical College, 523808 Dongguan, Guangdong China.
authors: Yong
authors: Y
authors: Liu
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Liuzhou People's Hospital, 545006 Liuzhou, Guangxi China.
authors: Peng
authors: P
authors: Xu
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Affiliated Cancer Hospital of Guangxi Medical University, 530021 Nanning, Guangxi China.
authors: Ke-Zhi
authors: KZ
authors: Li
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Key Laboratory of Biological Molecular Medicine Research of Guangxi Higher Education, 530021 Nanning, Guangxi China.
authors: Dan-Zhao
authors: DZ
authors: Cai
authors: Department of Biochemistry and Molecular Biology, Guangxi Medical University, 530021 Nanning, Guangxi China ; Key Laboratory of Biological Molecular Medicine Research of Guangxi Higher Education, 530021 Nanning, Guangxi China.
authors: Yu
authors: Y
authors: Luo