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ARS Home » Research » Publications at this Location » Publication #159158


item Johnson, Emanuel
item Zhang, Dapeng

Submitted to: Annals of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2004
Publication Date: 1/20/2005
Citation: Johnson, E.L., Zhang, D. 2005. Inter- and intra-specific variations among five erythroxlum taxa assessed by aflp. Annals Of Botany, 95:601-608.

Interpretive Summary: The purpose of this study was to tell how the four types of coca bushes, that are cultivated for cocaine, are different from one another. A study was conducted using DNA taken from the leaves of each coca bush and identified by a method called Amplified Fragment Length Polymorphism, (AFLP). AFLP is a method of analyzing plant DNA to show the differences between bushes. By comparing the coca bush DNA differences, we can see how closely related each sample was to one another. Once this data was collected, a genetic tree was constructed, like a family tree, to show how the samples related to each other. This research will be used by scientists and government agencies responsible for monitoring the source cocaine in coca bushes.

Technical Abstract: The four cultivated Erythroxylum taxa are indigenous to the Andean region of South America and were originally grown as a source of homeopathic medicine. There are two species of cultivated coca (Erythroxylum coca var. coca Lam [E. c. var. coca] and Erythroxylum novogranatense var. novogranatense (Morris) Hieron [E. n. var. novogranatense] each with a variety (Erythroxylum coca var. ipadu Plowman [E. c. var. ipadu] and Erythroxylum novogranatense var. truxillense (Rusby) Plowman [E. n. var. truxillense]. The two varieties are almost phenotypically indistinguishable from their species but morphologically distinguishable. This research uses AFLP with functional primers to determine the genetic diversity among and between the four cultivated and a feral Erythroxylum taxon, (Erythroxylum ulei O.E. Schulz) from our living collection. The level of intra-specific diversity varied significantly among the four cultivated taxa. E. c. var. coca had the highest mean distance (0.398), and E. c. var. ipadu the least (0.257). The mean distance within E. n. var. novogranatense was 0.322 and for E. n. var. truxillense, 0.314 and were intermediate. The intra-specific diversity between E. c. var. ipadu in our living collection vs. E. c. ipadu currently under cultivation in Colombia, South America is indicative of hybridization.