Spooner, David M. .
DNA barcoding: An oversimplified solution to a complex problem.
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), and the plastid markers trnH-psbA intergenic spacer, matK, and other plastid regions, with the first three being the most variable. This study tests the utility of barcoding with these three regions in a complicated plant group, Solanum sect. Petota; wild potatoes. These DNA regions fail to provide species-specific markers in sect. Petota because ITS has too much intraspecific variation and the plastid markers lack sufficient polymorphism. Wild potatoes are not alone in failing to work with barcoding regions. 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, and ignores substantial practical and theoretical problems in defining species.
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1 - USDA, Agricultural Research Service, Horticulture, University of Wisconsin, 1575 Linden Drive, Madison, WI, 53706-1590, U.S.A.
Potato (Solanum tuberosum)
Presentation Type: Workshop
Location: Blair CD/Gage
Date: Sunday, July 27th, 2008
Time: 9:00 AM