The differences between some species are imperceptible to the human eye.
Credit: Public domain
Plants Finally Get DNA Barcodes
By Stephen Leahy
The "barcode" of the plant world, the parts of the DNA unique to flora, has been revealed, thanks to a scientific breakthrough that could revolutionize herbal medicine and improve regulations of the timber trade.
MÉRIDA, Mexico, Nov 16 (Tierramérica).- Advances made in genetic profiling could be used to fight illegal timber trading, offer better regulation of herbal medicines and map entire food chains, according to experts at a conference of the Mexican Academy of Sciences.
"It's taken four years, but the new science of DNA (deoxyribonucleic acid) barcoding now has the crucial 'marker' for plants," said David Schindel, executive secretary of the Consortium for the Barcode of Life (CBOL).
"Biodiversity scientists are using DNA technology to unravel mysteries, much like detectives use it to solve crimes," Schindel told Tierramérica from Mexico City, where CBOL was co-host of the Nov. 10-12 conference of the Mexican Academy of Sciences with the Biology Institute of the Autonomous National University of Mexico (UNAM).
"This work in Mexico and elsewhere is enormously important," said Patricia Escalante, chair of the Institute's zoology department.
"Barcoding is a tool to identify species faster, more cheaply, and more precisely than traditional methods," Escalante stated in a press release.
DNA is a complex molecule containing all the genetic instructions for any organism to develop. While the DNA of a human is different and more complex than that of a worm, mouse DNA is quite similar to human DNA.
Several years ago, Canada's Biodiversity Institute of Ontario identified a portion of a gene called "cytochrome c oxidase I" that has proved to be the location of the unique "barcode" for all animal species. Knowing the location each species' unique barcode now allows scientists to quickly and easily identify them.
In a few years the technology is expected to progress to the point that identifying a species will require little more than taking a tissue sample and using a barcode scanner similar to those in use in a grocery stores, says Schindel.
While different areas of DNA have been identified that serve as the barcode regions for birds and for insects, plants had remained elusive, in part because there are an estimated 400,000 species of flora.
CBOL scientists can now compile a database of all known plant species with their unique barcodes, which can be utilized as a sort of global reference library.
In the near future, inspectors will be able to take a small sample from raw logs or lumber and determine if it is from illegally harvested trees.
Similar testing can also verify if an exotic wood is being sold at a premium price on the legal market is indeed what it claims to be. This can raise the value of the product and stem illegal trade or reveal fakes, according to Schindel.
The same is true for herbal medicines. Mixtures of dried and ground up herbal preparations are extremely difficult to identify without DNA barcoding, he says.
Mexico has roughly 800 species of cactus, some of which are very rare and prized by collectors. Many are used in landscaping. But there are no maps of the species' ranges and only a few experts in the world can identify individual species.
"If Mexico doesn't protect these rare species, they'll be gone, but first you have to know where they are," Schindel said.
DNA barcoding could help to map the distribution of each species. That, in turn, could open new markets for local people to sell cactus plants because officials could determine whether it could be done sustainably, he explained.
Legal versus illegal trade in wild animals is also difficult to sort out if there are no simple ways available to identify the species. In 2003 a Brazilian man was caught smuggling 58 eggs, which he claimed were quail eggs. But airport police suspected they might be parrots.
The eggs never hatched, but DNA barcoding showed three of the eggs were blue and gold macaws (a vulnerable species, according to IUCN, International Union for the Conservation of Nature), 51 blue-bellied or yellow-faced Amazon parrots (both near threatened species) and four yellow crowned Amazons, which are not threatened.
The applications for genetic profiling seem endless. In Mexico City, scientists from Spain announced they had DNA barcoded blood in the bellies of 100 mosquitoes, biting midges and sandflies to reveal which animals the insects bite besides humans.
According to a news release, they found the insects had bitten 18 mammals, including hares, partridges and mongoose, and 26 birds. The results are important to malaria and other disease vector research.
Canadian scientists presented new research based on the DNA analysis of bat guano, which revealed that eight bat species feed on over 300 types of insect - one of the largest food webs ever discovered.
This extension of DNA barcoding to unravel complex dynamics in the wild is an exciting new research field with important implications for nature conservation, Atilano Contreras, of the UNAM Institute of Biology, told Tierramérica.
While not in wide use yet in Mexico, DNA barcoding has identified several new species of parasites. Fungal parasites are believed to be the main cause of the worldwide decline in amphibians, Contreras said.
* IPS correspondent.