1. Commercial teas highlight plant
DNA barcode identification
successes and obstacles
Mark Y. Stoeckle, Catherine C. Gamble, Rohan Kirpekar,
Grace Young, Selena Ahmed, and Damon P. Little*

2. Commercial Teas Highlight Plant DNA
Barcode Identification Successes and
Obstacles
SUBJECT AREAS:
BIOINFORMATICS
EARTH AND ENVIRONMENTAL
SCIENCES Mark Y. Stoeckle1, Catherine C. Gamble2, Rohan Kirpekar2, Grace Young2, Selena Ahmed3
PLANT SCIENCES & Damon P. Little4
BIODIVERSITY
1
Program for the Human Environment, The Rockefeller University, New York, NY 10065, USA, 2Trinity School, New York, NY
10024, USA, 3Department of Biology, Tufts University, Medford, MA 02115, USA, 4Lewis B. and Dorothy Cullman Program for
Received Molecular Systematics, The New York Botanical Garden, Bronx, New York, NY 10458, USA.
25 May 2011
Accepted Appearance does not easily identify the dried plant fragments used to prepare teas to species. Here we test
6 July 2011 recovery of standard DNA barcodes for land plants from a large array of commercial tea products and
Published analyze their performance in identifying tea constituents using existing databases. Most (90%) of 146 tea
21 July 2011 products yielded rbcL or matK barcodes using a standard protocol. Matching DNA identifications to listed
ingredients was limited by incomplete databases for the two markers, shared or nearly identical barcodes
among some species, and lack of standard common names for plant species. About 1/3 of herbal teas
generated DNA identifications not found on labels. Broad scale adoption of plant DNA barcoding may
Correspondence and require algorithms that place search results in context of standard plant names and character-based keys for
requests for materials distinguishing closely-related species. Demonstrating the importance of accessible plant barcoding, our
findings indicate unlisted ingredients are common in herbal teas.
should be addressed to
M.Y.S.

3. Catherine Gamble
Grace Young Rohan Kirpekar

5. Camellia sinensis

6. samples
•146 products:
•33 manufacturers
•17 countries of origin
•73 Camellia sinensis (tea) products
•73 ‘herbal’ products
•44 listed a single plant ingredient
•29 listed 2–10 different plants
•82 plant common names on labels
•Herbs of Commerce (2nd Edition)

8. barcoding techniques
•morphologically homogenous samples (86%)
•one DNA extraction
•morphologically heterogeneous samples (14%)
•divided into morphologically homogeneous material
•average 3, range 2–8
•DNA extracted separately
•Qiagen DNeasy96 plant kit with added protease K
•matK: 3F/1R
•rbcL: F1/R634

10. ‘portable’ laboratory
•10 specimens reanalyzed
•processed by Catherine, Rohan, and Grace
•Qiagen DNeasy plant mini kit
•rbcL: F1/R634
•commercial sequencing facility (Macrogen)

11. barcode recovery
•90% readable barcodes
•96% of Camellia sinensis (tea) products
•84% of ‘herbal’ products
•79% matK
•40 haplotypes
•77% rbcL
•48 haplotypes
•66% matK+rbcL

12. matK

13. rbcL

14. label incompatibility
•4% of Camellia sinensis (tea) products
•35% of ‘herbal’ products

15. product: K24
ginger root, natural flavors, linden, lemon
label: peel, blackberry leaves, lemongrass, citric
acid
non–label
annual bluegrass (Poa annua)
DNA:
K24 rbcL is an exact match to Poa annua
(annual bluegrass), family Poaceae. Listed
interpretation: ingredient lemongrass (Citropogon citratus) is
also in Poaceae. K24 rbcL has lower identity to
C. citratus (94.0%; GQ436383).

16. product: MRa6
label: ginger, chicory
non–label
stevia (Stevia rebaudiana)
DNA:
MRa6 rbcL is an exact match to Stevia
rebaudiana, family Asteraceae, tribe
Eupatorieae. Listed ingredient chicory
interpretation: (Cichorium intybus) is also in family Asteraceae,
but in a different tribe, Cichoreae. MRa6 rbcL
has lower identity to C. intybus (97.4%;
L13652).