Scientists have extended the barcode of life to plants, a development that will have far reaching impacts in the years ahead.
Earlier this month, an international consortium of plant scientists achieved a milestone when they published the results of a multi-year analysis selecting two regions of DNA to serve as barcodes for the identification of plants. The findings were published in the Proceedings of the National Academy of Sciences.
The goal of using a standard segment of a gene as a unique identifier of all living organisms has worked better for animals than for plants, as a gene from the mitochondrial genome, cytochrome oxidase I or COI, is sufficiently different among animal species to allow unique identification of 95% of species. Since this gene is not highly variable in plants, 52 scientists from 24 institutions in nine countries have worked for several years to identify genetic sequences that can routinely be sequenced without ambiguous results and that differ enough to allow discrimination of species. The group selected two genes from the chloroplast genome, rbcL and matK, which together total about 1,450 base pairs.
Agreement on these barcode genes will pave the way to building the reference database necessary to assign barcode sequences to species. The use of barcodes will have tremendously broad impact both in the research community and also with many practical applications. Barcode sequences have in numerous instances helped identify species new to science and improve our understanding of diversity in the natural world. But more importantly it will enable plants that could formerly be identified only by increasingly rare experts with specific plant families to be identified by technicians, enabling broad ecological surveys. At a more practical level, it will support the identification of fragmentary plant materials in poison control centers and in other forensic applications, and allow accurate identification of ingredients in food and dietary supplements.
An ambitious effort to assemble barcodes for all of the trees of the world is being coordinated by The New York Botanical Garden, and it will ultimately facilitate better monitoring of the world timber trade. This international partnership will take years to complete its goal, but in the short term, enough sequence data has been collected already to identify the family to which most plants belong, and in many cases the genus as well. Timber harvesters will be much less likely to cut endangered timber species if they know that this technology may allow buyers to identify these species and refuse to accept and pay for them. Ultimately, barcoding will affect our lives in many ways by providing a method for the identification of the millions of species that inhabit our planet.
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Go out into your back yard (assuming you have one) and pretend you have to not only identify, but describe, designate, and catalog every plant that’s growing there. Now multiply that challenge by the entire surface of the Earth, and you’re standing in a botanist’s shoes. Of course, it’s not going to be as easy as all that; as a plant scientist, you’re also racing against a clock that stubbornly speeds up with each passing year. Climate change, human development, and myriad other influences are wiping out species before you’re even aware they’re under threat–and there are hundreds of thousands of species to account for. Worse, the system you use to designate these plants as endangered isn’t exactly marching to the beat of your own drum.
The 50-acre, old growth 
