DNA barcodes for plants a step closer
Biologists agree on genetic sequences to uniquely identify plant species.
Biologists have taken a major step forward in their plans to 'barcode' every species on the planet.
A database of barcode genetic sequences could allow easy identification of species in, for example, suspected illegal shipments of animal parts or areas being considered for environmental protection. Picking the most appropriate barcode gene for animals was relatively straightforward, but a floral equivalent has proved troublesome (see 'Botanical identities').
Now researchers have reached "broad community agreement" about two genes that could be used as the plant barcode. Approval of the agreement, outlined in a paper published in Proceedings of the National Academy of Sciences1, could trigger a rash of barcoding studies. It could also allow biologists to access funding from sources that so far have been reluctant to pay for such research because it might later be rendered partially obsolete.
"There is very clear desire in the community to reach some kind of agreement," says biologist Peter Hollingsworth, the lead author of the new paper and a researcher at the Royal Botanic Garden in Edinburgh, UK.
Cracking the code
A Who's Who of barcoding scientists can be found in the 52 authors of the new paper, which compares seven different DNA regions and assesses their suitability for a unique identifier for plants. The authors recommend that the barcode combine two regions, known as rbcL and matK.
Together these provide unique identification of 72% of the species tested and identify the correct species group for the rest.
"This [paper] captures the range of groups that have been comparing the different barcode regions," says Hollingsworth. "It represents an agreement to sequence the two loci that form the core barcode."
The new paper comes from the plant working group of the international Consortium for the Barcode of Life (CBOL), based at the Smithsonian National Museum of Natural History in Washington DC. It forms the basis of a submission that the group will make to the CBOL committee, who will arrange for it to be reviewed. They will then quickly come to a final decision on which genetic sequences should be used as the standard barcode for the international community.
"I am confident that this paper will seriously energize the assembly of a barcode reference library for plants," Paul Hebert, a researcher at the University of Guelph in Ontario, Canada, told Nature from the university's Arctic Churchill site in Manitoba, Canada, where he is working to barcode all eukaryotes at the site. "I believe that this paper will settle arguments in relation to the 'core' barcode loci for plants."
Hebert is not an author of the new paper but is heavily involved in a related project called International Barcode of Life (iBol), which moved into its preliminary 'one-year activation phase' this month and formally launches in July 2010.
A final decision, say those in the field, will not just speed up the barcoding process. It will also make it easier for relevant projects to obtain funding.
"[The lack of agreement] has been a hang-up in getting papers published and getting grants approved," says David Schindel, executive secretary of the CBOL. "It's been a very significant obstacle.
"I know of several big proposals that have gone to foundations and the foundation has said, 'We're very interested but we can't justify high levels of support for something that might involve the wrong guess.'"
He told Nature that providing the CBOL's plant working group can submit its recommendation within the next two weeks a decision should be made in the following six weeks. A final decision will come down to one of three possibilities, he says: the two-loci suggestion from the expert group, a three-loci code and a two-loci code plus an optional "insurance policy" region.
"I would say the first is the most likely, but I don't want to short-circuit the process," says Schindel. When a final decision comes, he says, "It's going to open up the flood gates."
- Hollingsworth, P. M. et al. Proc. Natl Acad. Sci. USA published online. doi:10.1073/pnas.0905845106 (2009).