Scientists Develop Bar-Code Standard for Plants

By Adrian Higgins
Washington Post Staff Writer
Thursday, July 30, 2009

An international panel of scientists has agreed to a bar-code standard for plant DNA that will allow the precise identification of most of Earth's 300,000 species of plants, according to a research report due to be published this week.

The agreement is expected to generate a wide range of benefits, from checking the purity of herbal supplements to exposing illegal logging operations and helping to protect fragile plant ecosystems, observers said.

"It's the first time we have actually developed a technique that will allow people to identify plants," said James S. Miller, vice president for science at the New York Botanical Garden, one of 25 institutions working on the agreement.

A similar technique for animals was created in 2003 and has been used to expose mislabeled caviar, crack a food-poisoning case involving fish and determine the bird species that caused US Airways Flight 1549 to ditch into the Hudson River in January.

In the animal and plant kingdoms, technicians use a short DNA sequence called a region to identify species. The one region chosen for animals has proven highly effective in identifying such diverse organisms as butterflies and birds. But researchers have found it far more difficult to establish a single bar-code standard for plants. It must contain a sequence that is universal to all plants yet unique to a species "over a tremendous variation of groups, from mosses and liverworts to flowering plants over several hundred millions of years," said David Schindel, executive secretary of the Washington-based Consortium for the Barcode of Life.

The 52-member Plant Working Group has recommended that two regions be used, after four years of scientific haggling that whittled the number to seven candidates. The recommendation is made in a research report in the Proceedings of the National Academy of Sciences.

Using both regions, technicians will be able to identify every plant genus and 72 percent of species once a bar-code database has been established at the GenBank library at the National Center for Biotechnology Information in Bethesda.

The consortium will convene a second team of independent scientists to review the recommendations and could approve them in six weeks, Schindel said.

"It was both scientifically and sociologically difficult," said Schindel. "Sociologically, it was difficult because people work in different taxonomic groups. A region that works well for pine trees doesn't work as well for flowering plants."

Until now, plant identification has been the realm of highly skilled botanists and taxonomists who have relied on the plants' physical structures to describe them. The breakthrough will allow far more people to identify plants. "I have high school students doing the mechanics of bar coding," said Damon Little, assistant curator of bioinformatics at the botanical garden.

In addition, the DNA tests will allow the identification of plant fragments that otherwise would be impossible or difficult to determine. The technique will aid in forensic investigations and the analysis of imported timber.

The bar codes will also help verify the discovery of new plant species. "Maybe 15 to 20 percent of the world's plants remain to be described," Miller said.

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