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A system modeled on commercial bar codes may soon enable anyone to identify any plant from a small fragment of its DNA.
What the heck are these? The documents tor this crate say the contents are Polypodium ferns. Those are perfectly legal to import, but all the leaves have been hacked off these plants. I can't identity them from the stems alone. Jim, can yon get a reading on them?"
"Sure-just a second. . . . Well, according to my Global Flora Scanner, they're actually Strangeria eriopus, the Natal grass cycad, which looks a lot like a fern. It's an endangered species from Mozambique-says here they're just about extinct in the wild. They're illegal to import, but collectors are just crazy about them. Apparently some cycads sell for as much as $20,000 on the black market. I've never intercepted Stragerias here at the airport before. Good thing you spotted them-and that they were in the GFS database. We'd better investigate; this should mean a big fine or even an arrest for the importer."
The dialogue might sound like science fiction, but that kind of scenario could transpire sooner than you think. One of the great biological projects of our tune will be to collect DNA sequences from every living species on Earth. The objective is to create a universal genetic database of life. Once it is mostly complete - perhaps a decade from now - the project will enable any plant, animal, fungus, or other organism to be identified simply by sampling its DNA and comparing that with the database of known DNA sequences.
That comprehensive approach to identifying species is called DNA bar coding. As the name implies, the idea is to develop, as explicitly as possible, the analogy with the universal product codes, or bar-code labels, that are attached to nearly every consumer product, from applesauce to zucchini bread. What makes the analogy such a good one? Just as varying the order ot thin and thick black lines in the bar code of a product can distinguish one brand ot cough syrup from another at the checkout counter, so the varying order of the tour kinds of nucleotides that make up any fragment of DNA can make it possible to distinguish a...