Bar coding is no longer a term only associated with consumer goods, thanks to the research efforts of the University of Johannesburg’s (UJ) Dr Michelle van der Bank and a group of international scientists.
They have identified the matK gene — a gene that distinguishes the majority of plant species on earth.
The breakthrough was instrumental in the launch of an ambitious project to create a database of DNA information from the world’s tree species. This campaign comprises nine regional working groups, representing the entire world.
Van der Bank and Olivier Maurin of UJ’s botany and plant biotechnology department and Professor Adeniyi Jaeola of the University of Ibadan, Nigeria, head the regional working group for Africa.
Known as TreeBOL, or tree barcode of life, the project will keep track of where tree species are located and whether they are at risk for extinction.
“A section of the DNA would be used as a bar code, similar to the way a product at the grocery store is scanned to view its price. But with plants and animals, the scanners look at the specific order of the four basic building blocks of DNA to identify the species,” says Van der Bank.
She says: “the resulting database will help identify many of Africa’s trees and the world’s existing plant species, in the environment which they are located and whether they are endangered.
“The results are crucial for conservation and protecting the environment as population and development increases.”
“The ultimate goal is to establish a network of African scientists and institutes working in the field of DNA bar coding,” she said.
The South African National Biodiversity Institute (Sanbi) is the first organisation to commit to this African campaign. Researchers from Sanbi will assist in the collection of samples of about 1 700 trees native to Southern Africa. These samples will be deposited in the DNA Bank at UJ.
The project will also assist Sanbi to improve its electronic information base on South and Southern Africa trees and facilitate the expansion of its national plant collecting programme.
Why bar code trees?
In Africa the use of trees for firewood, construction, medicine and food is commonplace. As a result many tree species are listed as critically threatened or endangered.
“Many tree species may become extinct even before they are discovered, if no drastic change in human behaviour occurs.
“Given the predicted climate changes, we can expect important modifications to the biosphere in the next few decades, which may cause the extinction of a third of species on Earth by 2050,” says Van der Bank.
More than 300 species of timber trees are protected or have been considered for protection by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites).
A number of tree ferns, cycads, palms and columnar cacti are also Cites-protected tree species. Border control officials are often left helpless in monitoring illegal trafficking of these, which are difficult or impossible to identify using traditional taxonomic procedures.
Reasons for this are twofold: firstly the identification of immature trees is nearly impossible in the absence of flowers or fruits. Also tree species identification is more problematic when plants are cut, stripped of their leaves and processed into lumber or other timber products.
Living trees are difficult to identify when one is presented with only fragments from an individual specimen. Each of these provides an example of the way in which accurate tools for tree identification might be used.
At present one can use photographic guides to the leaves and/or bark of the tree species, field guides that may provide technical keys to the trees of an area, encyclopedias of timber cross-sections and even collections of wood blocks to assist in the identification of trees.
Each of these tools offers advantages to the user but also has its limitations. Because of this the development of a genetic tool for tree species identification would provide an unparalleled level of opportunity for scientists and consumers (such as commercial companies wishing to verify and guarantee the origin of their products).
DNA bar coding is one such technique that is relatively simple to apply and yet can distinguish even between closely related species or strains. In the long term, bar coding enthusiasts envisage something called a bar coder, a hand-held device that reads barcodes on the spot.
The first TreeBOL workshop in Africa will be held at UJ in October 2008. The aim of the workshop is to identify key species based on their conservation and trade status and also to establish partnerships between UJ and stakeholders.