U of G Scientists Help Find Plant DNA Barcode

July 28, 2009 - News Release

It will now be possible to genetically differentiate the more than 400,000 species of land plants in the world thanks to DNA barcoding, a revolutionary technique invented at the University of Guelph.

An international team of 52 scientists - including seven from U of G - has concluded a four-year effort to find a standard “plant DNA barcode.” Their findings appear in this week’s Proceedings of the National Academy of Sciences, one of the world’s most-cited multidisciplinary scientific serials.

The research involved scientists from 10 countries. Significant elements of data gathering and analysis were conducted at the Canadian Centre for DNA Barcoding (CCDB), which is based at U of G’s Biodiversity Institute of Ontario.

Having a standard approach for plant barcoding will accelerate the process of building a shared resource for plant identifications, said integrative biology professor Mehrdad Hajibabaei, CCDB’s associate director.

Peter Hollingsworth, head of genetics and conservation at the Royal Botanic Garden in Edinburgh who led the international research team, added: “Identification is important. It’s not possible to know if a plant is common or rare, poisonous or edible, being traded legally or illegally etc., unless it can be identified. But identification can be difficult: there are a large number of plant species and some look very similar.”

DNA barcoding is one way around the problem. Invented by U of G integrative biology professor Paul Hebert, it involves using a short standardized region of DNA for identifying species. Hebert called the system DNA barcoding, analogous to how retail products are tagged to allow for quick identification. It reduces species identification time to hours and, eventually, to minutes.

The short barcode sequence is used to assign any specimen to a known species or to a new one by matching it against a reference library of sequences. Analysis extends to all life stages and to fragments of organisms.

In animals, DNA barcoding has been used successfully to distinguish among species since 2003. A barcode library of approximately 60,000 animal species has been amassed already, based on the standard region selected six years ago. It’s also led to the discovery of overlooked species of birds, bats, butterflies, fishes and marine algae.

But plant biologists have had a far more difficult time adopting a universal plant barcode. This is because in animals or insects, scientists can identify species with a short DNA sequence from a mitochondrial gene called CO1. But the gene doesn't vary enough in plants to provide reliable species identification. And, until now, there was no consensus as to which DNA regions are the most suitable for plant barcoding.

“Two major principles have made DNA barcoding a success for animal species identification: standardization and minimalism,” Hajibabaei said. "This study presents a major milestone because we now have a DNA barcode standard for plant species as well.”

Scientists involved in the project spent four years pooling their data before agreeing on a standardized approach. The selected plant barcode involves portions of two genes (rbcL and matK) from the plastid genome. Plastids are found in most plant cells and, among other things, are involved in the process of photosynthesis.

Plant DNA barcoding will work with minute amounts of tissue and can be used on fragments of plant material. Applications include identifying illegal trade in endangered species, identifying invasive organisms or poisonous species, and in improving conservation efforts.

The method will be used immediately in global projects such as Tree-BOL which aims to build the DNA barcodes database for the world’s 100,000 tree species, many of which are of economic and conservation importance.

In addition to Hajibabaei, the project also involved U of G integrative biology professors Brian Husband and Steve Newmaster; Sujeevan Ratnasingham, who heads BIO’s informatics group; and post-doctoral researchers Aron Fazekas, Prasad Kesanakurti and Isabelle Meusnier.

Other universities involved in the study are: the University of British Columbia, University of Toronto, University of Johannesburg, Korea University, Universidade Estadual de Feira de Santana, Universidad de Costa Rica, Columbus State University, University of Wisconsin, Universidad de los Andes Aberystwyth University, University of Cape Town, Hallym University, Seoul National University, University of Copenhagen, Universidad Nacional Autónoma de México and Imperial College London.

Agencies that participated in the research include the National Center for Biotechnology Information, the Smithsonian Institution, the Natural History Museum in London, the South African National Biodiversity Institute, the Natural History Museum of Denmark and the New York Botanical Garden.

Prof. Mehrdad Hajibabaei
Biodiversity Institute of Ontario
519 824-4120, Ext. 52487

For media questions, contact Communications and Public Affairs: Lori Bona Hunt, 519-824-4120 Ext. 53338 lhunt@uoguelph.ca.

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