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DNA Barcoding
DNA barcoding quickly became one of the buzzwords in biology. The goal of this international effort is to establish an easy and cost-effective way of species identification, by reading a standardized region of DNA in a biological sample. The idea is not new, of course. For the past several decades, scientists have been using DNA sequences to construct evolutionary history of animals and plants, or identifying pathogens. However, the DNA regions that they have been using are chosen to optimize the resolution for their specific experimental purpose. What makes the DNA barcoding radically different lies in the standardization of the DNA region for all the species in the world, or at least for major taxa such as kingdoms. There is a lot of appeal to it, which I will describe later.
DNA Barcoding Project at IIAR
We have initiated a DNA barcoding project here at the Indian Institute of Advanced Research for several reasons. First, we are a young institute established in 2006 and needed a project that does not require an established infrastructure, and yet that can be a pioneering work in modern science. For animals, a consensus has been reached that a mitochondrial DNA region that code for cytochrome c oxydase (COI) is most suitable for barcoding, but for plants, COI DNA sequence lacks variation to identify samples accurately at the species level. Several alternative regions have been proposed, but the utility of these DNA regions are still under testing. We are hoping to test some of the promising regions in local acacia species, which are prominent in our locale.
Second, after we establish the barcoding standard for acacia species, we want to expand our expertise to the identification of medicinal and aromatic plants. India is home to the biodiversity of these herbs and has a long history of utilizing these plants in traditional folk medicine, such as ayurveda. However, adulteration of medicines by contaminating cryptic (morphologically indistinguishable) species has been a problem. We hope to help solve the problem by successful barcoding of these herbs.
Significance of Barcoding the DNAs
DNA barcoding can potentially change the way people identify species and biological products derived from them. Barcoding requires a very small piece of sample. It can identify species by sampling a small quantity of market products, such as fish meat, which may be illegally caught, or herb mixture which may not have any medicinal value. Another advantage is that barcoding makes the identification easy and accurate for any non taxonomist. For example, many look-alike mosquitoes exit, but only certain species can cause malaria. This will aid epidemiological studies and eradication efforts. In the same token, the identification of local acacia species and subspecies has not been quite straightforward, and available descriptions of acacia species are sometimes confusing. It is hoped that accurate identification will become possible when our study is completed.
To collect acacia samples, we travel to various locations in Gujarat, although so far, we have covered only the locations around Gandhinagar. We first spot acacia trees and tag each tree with metal plate with a sample number, and then collect leaves, flowers, and pods. The specimens are preserved for later deposition in herbaria, and at the same time, genomic DNA is extracted from them. The DNA samples are used for PCR with primers proposed internationally for barcoding and the products are sequenced, and analyzed. Dr. Rajani Nadgauda, who is the group leader of the Plant Science department of the institute, has been very supportive of the project and undertook all the logistics and business part of the work. The main force of the project is Dr. Neeraj Jain and Soni Gupta, whom you can see in some of the pictures. Their expert work has been producing results that are promising for our goals.