ACS Distance Education UK
DNA barcoding is a taxonomic method used to identify plants by extracting DNA from a tiny sample of plant material. DNA barcodes are small sections of DNA code (between 400 and 800 base pairs) that are identifiable as belonging to a particular species. In land plants, standardised regions of DNA found on genes in the chloroplasts, are typically used. DNA barcoding offers a quick and accurate analysis of plant samples, allowing the user to retrieve information about known plant species.
The main problem with identifying plants using anatomical characteristics is the limitations of identifying plant samples correctly in a quick and repeatable manner. Plants of the same species can differ dramatically in their appearance depending on their stage of life, condition, habitat etc, so this adds to the difficulty in identifying plants based on their anatomy.
DNA barcoding was initially developed as a taxonomic tool to counteract the limitations faced in order to facilitate species identification. DNA barcoding makes it possible to identify a plant species at all life stages, for example through sampling a fruit, seed, immature plant and mature plant. It can also be used to analyse plant samples that are damaged and may otherwise be unidentifiable. Furthermore, DNA barcoding may even be used to identify species in the gut contents and faeces of animals.
Using DNA barcoding as a method to identify plants requires the following:
Known plant species are recorded in a database that serves as a DNA barcode library.
The DNA barcode of a plant specimen that requires identification is matched against the DNA barcode library.
Using DNA barcoding as a taxonomic tool has many applications including:
A problem with DNA barcoding at the time of writing is that not all species are in the barcode library and so a negative result may be interpreted as a new species.