The Barcode Blog

A mostly scientific blog about short DNA sequences for species identification and discovery. I encourage your commentary. -- Mark Stoeckle

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Tea time for DNA

What’s in your favorite tea? The dried and sometimes cooked or fermented bits of plants used to make teas are not easily identified to species by appearance. Over the past year I have been involved in a project testing whether DNA barcoding can identify the ingredients in commercial tea products, working with three New York City high school students and plant experts from Tufts University (Selena Ahmed) and The New York Botanical Garden (Damon Little). Student investigators Katie Gamble, Rohan Kirpekar, and Grace Young collected 146 tea products from 25 NYC locations, representing 33 manufacturers, 17 countries, and 82 plant common names–73 products were regular teas (prepared from Camellia sinensis, the tea plant) and 73 were herbal products prepared from other plant species.

Our findings are published in 21 July 2011 Scientific Reports, (Nature Publishing Group’s open access journal). About 1/3 of herbal teas generated DNA identifications indicating unlisted ingredients including weeds like annual bluegrass (Poa annua) and white goosefoot (Chenopodium album) and herbal plants like chamomile (Matricaria recutita). Matching DNA ingredients to listed ingredients was sometimes challenging–we observe that “broad-scale adoption of plant DNA barcoding may require algorithms that place search results in context of standard plant names and character-based keys for distinguishing closely-related species.”

We are pleased that our investigation has attracted press coverage including New York Times print and online editions and internationally in 65 news sites and 14 countries, including India and China, world centers of tea production. Most of the DNA work was done at The New York Botanical Garden in senior author Damon Little’s laboratory. For a small subset of samples (10) we did DNA isolation and amplification in my dining room with recycled lab equipment purchased on the internet for about $5000. Samples were mailed to a commercial facility (Macrogen) for DNA sequencing, with results available by email the next day. It cost about $15 a sample including sequencing (unidirectional). More info and pictures on our TeaBOL website!

What’s next? I am excited about enabling wider use of DNA barcoding by high school students, including Cold Spring Harbor’s Urban Barcode Project competition (I am an advisor), open to teams from all New York City schools, with a focus on public institutions. I expect that soon manufacturers of teas and herbal products (and regulators) will incorporate DNA barcode testing into their quality control practices. One of the important tasks for scientists is building up the reference databases. At the time of the study, BOLD (Barcode of Life Database) and GenBank lacked rbcL or matK records for about 1/3 of plant species listed on product labels in our study. More on herbal plant identification: (Lou et al 2010. An integrated web medicinal materials DNA database. BMC Genomics 11, 402; Smillie and Kahn 2010. A comprehensive approach to identifying and authenticating botanical products. Clin Pharm Therapeutics 87, 175).


This entry was posted on Friday, July 22nd, 2011 at 2:58 pm and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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About this site

This web site is an outgrowth of the Taxonomy, DNA, and Barcode of Life meeting held at Banbury Center, Cold Spring Harbor Laboratory, September 9-12, 2003. It is designed and managed by Mark Stoeckle, Perrin Meyer, and Jason Yung at the Program for the Human Environment (PHE) at The Rockefeller University.

About the Program for the Human Environment

The involvement of the Program for the Human Environment in DNA barcoding dates to Jesse Ausubel's attendance in February 2002 at a conference in Nova Scotia organized by the Canadian Center for Marine Biodiversity. At the conference, Paul Hebert presented for the first time his concept of large-scale DNA barcoding for species identification. Impressed by the potential for this technology to address difficult challenges in the Census of Marine Life, Jesse agreed with Paul on encouraging a conference to explore the contribution taxonomy and DNA could make to the Census as well as other large-scale terrestrial efforts. In his capacity as a Program Director of the Sloan Foundation, Jesse turned to the Banbury Conference Center of Cold Spring Harbor Laboratory, whose leader Jan Witkowski prepared a strong proposal to explore both the scientific reliability of barcoding and the processes that might bring it to broad application. Concurrently, PHE researcher Mark Stoeckle began to work with the Hebert lab on analytic studies of barcoding in birds. Our involvement in barcoding now takes 3 forms: assisting the organizational development of the Consortium for the Barcode of Life and the Barcode of Life Initiative; contributing to the scientific development of the field, especially by studies in birds, and contributing to public understanding of the science and technology of barcoding and its applications through improved visualization techniques and preparation of brochures and other broadly accessible means, including this website. While the Sloan Foundation continues to support CBOL through a grant to the Smithsonian Institution, it does not provide financial support for barcoding research itself or support to the PHE for its research in this field.