Botany to turn over a new leaf as DNA barcodes speed up plant identification

SCOTS scientists have led the way in developing a system of DNA "barcodes" for plants that will enable species all over the world to be identified.

Whereas it has become commonplace to use DNA to identify humans and other animals, it has not so far been a regular procedure with plants.

Currently, it can be necessary to wait until a plant or tree grows and flowers before it can be identified. However, using this technique, a small piece of a sapling could enable botanists to reveal the species immediately.

The research, led by a team at the Royal Botanic Garden Edinburgh, means this tool will now be available to botanists, meaning that scientists will be able to identify plants anywhere in the world, even if just a small leaf fragment is available.

This will help build up a picture of plant biodiversity and it will mean conservation efforts can be better targeted.

The technique could also be used to test for plants being imported illegally into the UK, to identify poisonous plants, to reveal whether alien species have arrived in the country, or even to determine which plant species is present at a crime scene.

Dr Peter Hollingsworth, head of genetics and conservation at the Royal Botanic Garden Edinburgh, said: "It is not possible to know if a plant is common or rare, poisonous or edible, being traded legally or illegally, unless it can be identified.

"Conservation prioritisation, in particular, can be impeded by a lack of knowledge of what species grow where.

"But identifications can be difficult: there are a large number of plant species and some look very similar."

Each species of plant has a unique sequence of DNA, which can be read using a machine. This unique "barcode" will be saved on a database of species types, which now has to be built up.

It is hoped this plant barcode library will eventually contain the details of all 400,000 or so plant species in the world. Already a project called Tree-BOL is aiming to build the DNA barcodes database for the world's 100,000 tree species.

Dr Hollingsworth said in the future the ideal scenario would be to have hand-held machines that could be used in the field.

He told The Scotsman the technique would be useful because it can be extremely difficult to tell some plants apart.

"Some things that we are very familiar with you can identify very easily. However, even very good botanists going to areas that they haven't been before will find local plants they are not familiar with."

An international team of 52 scientists working in ten countries spent four years agreeing which DNA barcode to use.

Dr David Schindel, executive secretary of Washington DC-based Consortium for the Barcode of Life, which instigated the formation of the plant working group, said: "Having an agreed-upon barcode region will enable plant barcoding to accelerate rapidly. There are researchers around the world and diverse users of plant identification who are eager to get started."

The selected plant barcode involves portions of two genes – rbcL and matK – from the plastid genome.

The researchers used 400 plant samples to test the technique. In 72 per cent of cases they were immediately able to determine the correct species of plant, and in the rest of the cases were able to place the plant in a group of related species.

The results of the study are published in the Proceedings of the National Academy of Sciences.

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