DNA BARCODING WILL FREQUENTLY FAIL IN COMPLICATED GROUPS: AN EXAMPLE IN WILD POTATOES

DNA bat-coding (barcoding) has been proposed as a rapid and practical molecular method to identify species via diagnostic variation in short orthologous DNA sequences from one or a few universal genomic regions. It seeks to address ill a rapid and simple way the taxonomic impediment of a greater need for taxonomic identifications than call be supplied by taxonomists. Using a complicated plant group, Solanum sect. Petota (wild potatoes). I tested barcoding with the most variable and frequently Suggested plant barcoding re.-ions: the internal nontranscribed spacer of nuclear ribosomal DNA (ITS) and the plastid markers trnH-psbA intergenic spacer and matK. These DNA regions fail to provide species-specific markers in sect. Petota because the ITS has too much intraspecific variation and the plastid markers lack sufficient polymorphism. The complications seen in wild potatoes are common in many plant groups, but they have not been assessed with barcoding. Barcoding is a retroactive procedure that relies oil well-defined species to function, is based solely oil a limited number of DNA sequences that are often inappropriate at the species level, has been poorly tested with geographically well-dispersed replicate samples front difficult taxonomic groups. and discounts substantial practical and theoretical problems in defining species.