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United States Department of Agriculture

Agricultural Research Service

Title: DNA barcoding: An oversimplified approach to a complex problem

item Spooner, David

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2008
Publication Date: 8/5/2008
Citation: Spooner, D.M. 2008. Dna barcoding: an oversimplified approach to a complex problem [abstract]. Botany without Borders. p. 1024.

Interpretive Summary:

Technical Abstract: DNA barcoding (“barcoding”) has been proposed as a rapid and practical molecular tool to identify species via diagnostic variation in short orthologous DNA sequences from one or a few universal genomic regions. It seeks to overcome the “taxonomic impediment” caused by a greater need for species identifications than the supply of taxonomic specialists. A number of barcoding regions have been proposed for plants, including the internal non-transcribed spacer of nuclear ribosomal DNA (ITS), the plastid trnH-psbA intergenic spacer, and other plastid regions, with the first two being the most variable. This study tests the utility of DNA barcoding with these two most variable regions in a complicated plant group, Solanum sect. Petota; wild potatoes. These two DNA regions fail to provide species-specific markers in sect. Petota because ITS has too much intraspecific variation and the trnH-psbA intergenic spacer lacks of sufficient polymorphism. Wild potatoes are not alone in failing to work with barcoding regions and barcoding has many other problems discussed here. Addressing the taxonomic impediment will require a comprehensive and integrative program of research and training using a variety of data sets appropriate to different species groups. Barcoding, in contrast, is impeded by common complicating biological phenomena, is a retroactive procedure that relies on well defined species to function, is based solely on DNA sequences that are often inappropriate at the species level, has been poorly tested with replicate samples, is not cost effective, and ignores substantial unresolved practical and theoretical problems in defining species.

Last Modified: 10/18/2017
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