Consortium For Barcode Of Life Research Articles

DNA barcoding, an effective tool for species identification: a review.

DNA barcoding is a powerful taxonomic tool to identify and discover species. DNA barcoding utilizes one or more standardized short DNA regions for taxon identification. With the emergence of new sequencing techniques, such as Next-generation sequencing (NGS), ONT MinION nanopore sequencing, and Pac Bio sequencing, DNA barcoding has become more accurate, fast, and reliable. Rapid species identification by DNA barcodes has been used in a variety of fields, including forensic science, control of the food supply chain, and disease understanding. The Consortium for Barcode of Life (CBOL) presents various working groups to identify the universal barcode gene, such as COI in metazoans; rbcL, matK, and ITS in plants; ITS in fungi; 16S rRNA gene in bacteria and archaea, and creating a reference DNA barcode library. In this article, an attempt has been made to analyze the various proposed DNA barcode for different organisms, strengths & limitations, recent advancements in DNA barcoding, and methods to speed up the DNA barcode reference library construction. This study concludes that constructing a reference library with high species coverage would be a major step toward identifying species by DNA barcodes. This can be achieved in a short period of time by using advanced sequencing and data analysis methods.

DNA barcoding as a valuable molecular tool for the certification of planting materials in bamboo

DNA barcodes developed for selected commercially important bamboo species can be utilized for the certification of planting stock in bamboo nurseries in absence of discriminatory features at the juvenile stage. Planting materials such as micropropagated plantlets, rhizome transplants and culm cuttings, generated at nursery level are directly procured for establishment of commercial plantations without any further verification. Very often misidentification and mixing up occur at nursery level and the error is not discovered until several years have passed. The present study evaluated the potentiality of seven Consortium for Barcode of Life (CBOL) recommended standard DNA barcode regions in commercially important bamboo species of India. Among the analyzed barcode regions, multiple sequence alignment (MSA) of psbA-trnH barcode region showed species-specific nucleotide differences in the studied bamboo taxa. The major nucleotide changes observed were transitions/transversions as well as insertions/deletions of nucleotides. Even though species-specific mononucleotide differences could be identified for most of the studied bamboo taxa, a small amount of sequence similarities were found in some of the Dendrocalamus and Bambusa species, which were grouped together in tree-based analysis. In subtribe Melocanninae, Ochlandra travancorica, Melocanna baccifera and M. clarkei showed unique species-specific psbA-trnH barcodes. Similarly, in the genus Oxytenanthera, unique species-specific psbA-trnH barcodes were obtained for O. monadelpha and O. parvifolia. Thus psbA-trnH barcode region generated distinct species-specific barcodes for commercial bamboo species in genera Bambusa, Dendrocalamus, Melocanna, Oxytenanthera as well as Ochlandra. Any national certification agency set up for the purpose can utilize psbA-trnH DNA barcode region to tag species identity and to establish the authenticity of multiplied planting materials in bamboos.

The loci recommended as universal barcodes for plants on the basis of floristic studies may not work with congeneric species as exemplified by DNA barcoding of Dendrobium species

BackgroundBased on the testing of several loci, predominantly against floristic backgrounds, individual or different combinations of loci have been suggested as possible universal DNA barcodes for plants. The present investigation was undertaken to check the applicability of the recommended locus/loci for congeneric species with Dendrobium species as an illustrative example.ResultsSix loci, matK, rbcL, rpoB, rpoC1, trnH-psbA spacer from the chloroplast genome and ITS, from the nuclear genome, were compared for their amplification, sequencing and species discrimination success rates among multiple accessions of 36 Dendrobium species. The trnH-psbA spacer could not be considered for analysis as good quality sequences were not obtained with its forward primer. Among the tested loci, ITS, recommended by some as a possible barcode for plants, provided 100% species identification. Another locus, matK, also recommended as a universal barcode for plants, resolved 80.56% species. ITS remained the best even when sequences of investigated loci of additional Dendrobium species available on the NCBI GenBank (93, 33, 20, 18 and 17 of ITS, matK, rbcL, rpoB and rpoC1, respectively) were also considered for calculating the percent species resolution capabilities. The species discrimination of various combinations of the loci was also compared based on the 36 investigated species and additional 16 for which sequences of all the five loci were available on GenBank. Two-locus combination of matK+rbcL recommended by the Plant Working Group of Consortium for Barcoding of Life (CBOL) could discriminate 86.11% of 36 species. The species discriminating ability of this barcode was reduced to 80.77% when additional sequences available on NCBI were included in the analysis. Among the recommended combinations, the barcode based on three loci - matK, rpoB and rpoC1- resolved maximum number of species.ConclusionsAny recommended barcode based on the loci tested so far, is not likely to provide 100% species identification across the plant kingdom and thus is not likely to act as a universal barcode. It appears that barcodes, if based on single or limited locus(i), would be taxa specific as is exemplified by the success of ITS among Dendrobium species, though it may not be suitable for other plants because of the problems that are discussed.