China
Africa
Explore chapters and articles related to this topic
Facts about Standardization of Herbal Medicines
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Vandana Garg, Ghazala Zia, Mahima Chauhan, Rohit Dutt
If the morphology of the two plants is quite similar and it is hard to distinguish or identify them even for an expert then DNA bar-coding is found to be helpful. DNA bar-coding in combination with High Resolution Melting analysis (Bar HRM) is an effectual, way to precisely identification of species in plants. Chloroplast DNA (cpDNA) is another suitable method used in the identification of plants (Kress et al., 2005). There is a region in the chloroplast genome of each plant species which show sufficient variation that will be convenient for identification. The CBOL Plant Working Group have studied about 907 plant species by using a variety of different gene and non-gene regions in the cpDNA and found that the two regions, rbcL, and matK, exhibit a promising efficient role in the discrimination in plant species (CBOL Plant Working Group, 2009). The greatest advantage of DNA metabarcoding is its ability to identify every single species within complex multi-ingredient and processed mixtures simultaneously (Raclariu et al., 2018). Only 15% of investigated Veronica herbal products contained the target species Veronica officinalis L., whereas the main known adulterant, Veronica chamaedrys L., was detected up to 62% (Raclariu et al., 2017).
Chloroplast DNA and Phylogenetic Relationships
Published in S. K. Dutta, DNA Systematics, 2019
Several features make chloroplast DNA a fairly “easy” molecule to use in systematic studies. Typically, several hundred to several thousand molecules of chloroplast DNA are present in a leaf cell.11,96,97 As a result it is relatively straightforward to isolate large amounts of sufficiently pure chloroplast DNA from many angiosperms.98,99 Although plant nuclear DNA is at least as easy to isolate as chloroplast DNA, very little mitochondrial DNA is present in plant cells and its purification is a formidable task for most species. The small size of the chloroplast genome is advantageous in two ways: the entire array of fragments produced by many restriction enzymes is conveniently visualized on a single agarose gel and individual genes can be readily identified and isolated for sequencing studies. The much larger sizes of plant nuclear100 and mitochondrial101 genomes make it impossible to satisfactorily analyze the complex patterns of the total genome as revealed by agarose gel electrophoresis. Instead, cloned sequences must be used as hybridization probes in order to reveal variation in only a portion of the genome. Moreover, the fact that plant nuclear DNAs are several orders of magnitude more complex than chloroplast DNAs makes it relatively difficult to isolate and clone specific nuclear genes.
Ribosomal RNA Processing Sites
Published in S. K. Dutta, DNA Systematics, 2019
Robert J. Crouch, Jean-Pierre Bachellerie
Recent reviews on the subject have been written by Bedbrook and Kolodner163 and by Rochaix.164 Chloroplast DNA from higher plants consists of an homogeneous population of covalently closed circular molecules,165,166 which according to the species, range in size from 120 to 190 kb.163 In most cases studied so far, the arrangement of chloroplast DNA is characterized by the presence of two chloroplast rRNA transcription units located in a long inverted repeat (22 to 25 kb) which separates two large single copy regions (averaging, respectively, 20 and 80 kb) as depicted in Figure 19a. The loss of one segment of the inverted repeat as observed in two legume species,167,168 has been correlated to extensive rearrangements of chloroplast DNA during phylogeny,169 as opposed to high conservation when both segments are present. Several experimental evidences are suggestive of the existence of a correction mechanism operating between the two segments of the inverted repeat, which should play a major role in the evolution of chloroplast genome.170,171
Phylogenetic analysis of Uncaria species based on internal transcribed spacer (ITS) region and ITS2 secondary structure
Published in Pharmaceutical Biology, 2018
Shuang Zhu, Qiwei Li, Shanchong Chen, Yesheng Wang, Lin Zhou, Changqing Zeng, Jun Dong
To summarize, the ITS region has more variable sites to discriminate Uncaria species and thus has better discriminating performance than does the ITS2 region. The phylogenetic relationships of most Uncaria species were able to be resolved, except for U. yunnanensis and U. lanosa. In additional, the chloroplast DNA regions (matK, rbcL, psbA-trnH, et al.) may be candidate barcodes to resolve the phylogenetic relationship between U. yunnanensis and U. lanosa.