Toronto, July 29 - Botanists have identified a pair of genes which can help catalogue plants worldwide, using a technique known as DNA bar coding.

'Bar coding provides an efficient means by which we can discover the many undescribed species that exist on earth,' said Spencer Barrett, professor of ecology and evolutionary biology at the University of Toronto (U-T), who led the study.

'This discovery is important because understanding biodiversity is crucial to long-term human existence on the planet,' he said.

DNA bar coding has been widely used to identify animal species since its invention five years ago. But its use for plants was delayed because of the complex nature of plant genetics and disagreements over the appropriate DNA regions to use.

'We compared the performance of the seven leading candidate gene regions against three criteria: ease of obtaining DNA sequences; quality of the DNA sequences; and ability to tell species apart based on a sample of 550 species of land plants,' said Barrett.