Random primed polymerase chain reaction differentiates Codonopsis pilosula from different localities

DNA barcoding, microarrays and next generation sequencing: recent tools for genetic diversity estimation and authentication of medicinal plants

DNA barcoding, microarray technology and next generation sequencing have emerged as promising tools for the elucidation of plant genetic diversity and its conservation. They are proving to be immensely helpful in authenticating the useful medicinal plants for herbal drug preparations. These newer versions of molecular markers utilize short genetic markers in the genome to characterize the organism to a particular species. This has the potential not only to classify the known and yet unknown species but also has a promising future to link the medicinally important plants according to their properties. The newer trends being followed in DNA chips and barcoding pave the way for a future with many different possibilities. Several of these possibilities might be: characterization of unknown species in a considerably less time than usual, identification of newer medicinal properties possessed by the species and also updating the data of the already existing but unnoticed properties. This can assist us to cure many different diseases and will also generate novel opportunities in medicinal drug delivery and targeting.

Molecular authentication of geo-authentic Scrophularia ningpoensis

Scrophularia ningpoensis has long been used in the Chinese Materia Medica for inflammation. Like other herbal medicines, S. ningpoensis collected from different localities may considerably differ in their therapeutic efficacy, and the one grown in Zhejiang Province is recognized as geo-authentic. However, it is difficult to confirm the geographical authenticity by similar morphological characteristics. In the present study, inter-simple sequence repeat (ISSR) markers were conducted to detect S. ningpoensis from different origins. A 1 259-bp fragment amplified by primer UBC874 was found only in geo-authentic ones. By cloning and sequencing that specific band, sequence characterized amplified region (SCAR) markers were designed to distinguish geo-authentic S. ningpoensis from others. This is a rapid and easy method that can be used to identify the geographical authenticity of S. ningpoensis.

DNA barcoding provides distinction between Radix Astragali and its adulterants

Based on variable nuclear and/or organellar DNA sequences among vastly divergent species as well as morphologically indistinguishable species, DNA barcoding is widely applicable in species identification, biodiversity studies, forensic analyses, and authentication of medicinal plants. The roots of Astragalus membranaceus and A. membranaceus var. mongholica are commonly used as Radix Astragali in several Asian countries, including China, Japan, and Korea. However, in addition to the two species recorded in the Chinese Pharmacopoeia, there are twenty-three species from different genera including Astragalus, Oxytropis, Hedysarum, and Glycyrrhiza, which have been used as adulterants not only in trading markets but also by the herbal medicine industry. Therefore, a simple, reliable, and accurate classification method is important for distinguishing authentic Radix Astragali from its adulterants. In this study, we acquired data for 37 samples from four related genera within the family Fabaceae. Then we compared four candidate DNA barcoding markers using ITS, matK, rbcL, and coxI sequences from nuclear, chloroplast, and mitochondrial genomes, all commonly used for plants to identify genetic variations among genera, intraspecies, and interspecies. We observed higher divergences among genera and interspecies for ITS, which have the average Kimura 2-parameter distances of 4.5% and 14.1%, respectively, whereas matK was found to have sufficient divergence at the intraspecific level. Moreover, two indels detected in the matK sequence are useful for PCR studies in distinguishing Radix Astragali from its adulterants. This study suggests that the combined barcoding regions of ITS and matK are superior barcodes for Radix Astragali and further studies should focus on evaluating the applicability and accuracy of such combined markers for a wide range of traditional Chinese herbs.

DNA methods for identification of Chinese medicinal materials

As adulterated and substituted Chinese medicinal materials are common in the market, therapeutic effectiveness of such materials cannot be guaranteed. Identification at species-, strain- and locality-levels, therefore, is required for quality assurance/control of Chinese medicine. This review provides an informative introduction to DNA methods for authentication of Chinese medicinal materials. Technical features and examples of the methods based on sequencing, hybridization and polymerase chain reaction (PCR) are described and their suitability for different identification objectives is discussed.

Molecular identification of Astragalus membranaceus at the species and locality levels

Astragalus membranaceus (Fisch.) Bunge, a commonly used Chinese medicinal material, from certain localities contains more favourable trace elements and fewer harmful trace elements than those from other localities. Therefore, there is a need to distinguish Astragalus membranaceus from different localities. Internal transcribed spacer 1 (ITS1) of the nuclear ribosomal RNA gene of 23 Astragalus membranaceus samples were sequenced to confirm the species of the samples. Arbitrarily primed polymerase chain reaction (APPCR) was then used to obtain unique fingerprints for each sample using several primers. The presence and absence of bands were used for calculating mean similarity indexes among the samples. It was found that the Heilongjiang samples were markedly distinguishable from samples of other localities. In addition, bands common for samples from the same locality were also identified and used to distinguish samples from Neimengu and Shanxi. Therefore, Astragalus membranaceus from these provinces, the major cultivation places in China, can be differentiated.

Application of cytochrome b DNA sequences for the authentication of endangered snake species

In order to enforce the conservation program and curbing the illegal trading and consumption of endangered snake species, the value of cytochrome b sequence in the authentication of snake species was evaluated. As an illustration, DNA was extracted, selected cytochrome b DNA sequences amplified and sequenced from six snakes commonly consumed in Hong Kong. Cataloging with sequences available in public, a cytochrome b database containing 90 species of snakes was constructed. In this database, sequence homology between snakes ranged from 70.68 to 95.11%. On the other hand, intraspecific variation of three tested snakes was 0-0.98%. Using the database, we were able to determine the identity of six meat samples confiscated by the Agriculture, Fisheries and Conservation Department, HKSAR.

Authentication of Panax ginseng and Panax quinquefolius using amplified fragment length polymorphism (AFLP) and directed amplification of minisatellite region DNA (DAMD)

AFLP profiles characteristic to Panax ginseng and Panax quinquefolius were generated using primers E-AGG/M-CAA. P. ginseng samples from different farms in China and Korea are homogeneous genetically [similarity index (SI) = 0.88-0.99], whereas samples of P. quinquefolius from different sources are much more heterogeneous (SI = 0.64-0.96). Detailed analysis of one of the polymorphic bands in P. ginseng led to the identification of a minisatellite Pg2, which contains eight repeats of 5'-AGGACTCATCACATTGTTACTC. The minisatellite DNA was consequently used in directed amplification minisatellite region DNA analysis to authenticate the two ginsengs.