title: Differentiation of the Chinese minority medicinal plant genus Berchemia spp. by evaluating three candidate barcodes.
abstract: The genus Berchemia comprises important Chinese plants with considerable medicinal value; however, these plants are often misidentified in the herbal medicinal market. To differentiate the various morphotypes of Berchemia species, a proficient method employing the screening of universal DNA barcodes was used in this work. Three candidate barcoding loci, namely, psbA-trnH, rbcL, and the second internal transcribed spacer (ITS2), were used to identify an effective DNA barcode that can differentiate the various Berchemia species. Additionally, PCR amplification, efficient sequencing, intra- and inter-specific divergences, and DNA barcoding gaps were employed to assess the ability of each barcode to identify these diverse Berchemia plants authentically; the species were differentiated using the Kimura two-parameter and maximum composite likelihood methods. Sequence data analysis showed that the ITS2 region was the most suitable candidate barcode and exhibited the highest interspecific divergence among the three DNA-barcoding sequences. A clear differentiation was observed at the species level, in which a maximum distance of 0.264 was exhibited between dissimilar species. Clustal analysis also demonstrated that ITS2 clearly differentiated the test species in a more effective manner than that with the two other barcodes at both the hybrid and variety levels. Results indicate that DNA barcoding is ideal for species-level identification of Berchemia and provides a foundation for further identification at the molecular level of other Rhamnaceae medicinal plants.
authors.affiliation: Hubei University of Chinese Medicine, Wuhan, 430065 China ; Guangxi Institute of Minority Medicine, Nanning, 530001 China.
authors.forename: Li-Cheng
authors.initials: LC
authors.lastname: Guo
authors.affiliation: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700 China ; Medical Laboratory College, Beihua University, Jilin, 132013 China.
authors.forename: Ming-Ming
authors.initials: MM
authors.lastname: Zhao
authors.affiliation: Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700 China.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.affiliation: Guangxi Institute of Minority Medicine, Nanning, 530001 China.
authors.forename: Hong-Li
authors.initials: HL
authors.lastname: Teng
authors.affiliation: Hubei University of Chinese Medicine, Wuhan, 430065 China.
authors.forename: Bi-Sheng
authors.initials: BS
authors.lastname: Huang
authors.affiliation: Guangxi Institute of Minority Medicine, Nanning, 530001 China.
authors.forename: Xiang-Pei
authors.initials: XP
authors.lastname: Zhao
keywords: Berchimia spp.; Chinese minority medicinal plants; ITS2 DNA barcode; Pairwise distance analysis; Species identification