USDA, Agricultural Research Service, Department of Horticulture, University of Wisconsin, 1575 Linden Drive, Madison, Wisconsin 53706-1590 USA.
Am J Bot. 2009 Jun;96(6):1177-89. doi: 10.3732/ajb.0800246. Epub 2009 May 7.
DNA barcoding ("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 in a rapid and simple way the "taxonomic impediment" of a greater need for taxonomic identifications than can 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 regions: 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 on well-defined species to function, is based solely on a limited number of DNA sequences that are often inappropriate at the species level, has been poorly tested with geographically well-dispersed replicate samples from difficult taxonomic groups, and discounts substantial practical and theoretical problems in defining species.
DNA 条形码技术（“条形码”）已被提议作为一种快速实用的分子方法，通过来自一个或几个通用基因组区域的短同源 DNA 序列中的诊断变异来识别物种。它旨在以快速简单的方式解决“分类学障碍”，即需要进行的分类鉴定远远超过分类学家所能提供的鉴定。我使用一个复杂的植物群——Solanum 族 Petota（野生土豆），用最具变异性和最常被建议的植物条形码区域——核核糖体 DNA（ITS）的内部非转录间隔区和质体标记 trnH-psbA 基因间隔区和 matK——来测试条形码技术。这些 DNA 区域在 Petota 族中无法提供种特异性标记，因为 ITS 具有太多种内变异，而质体标记缺乏足够的多态性。在野生土豆中看到的复杂性在许多植物群中很常见，但尚未用条形码技术进行评估。条形码技术是一种回溯性程序，依赖于定义明确的物种才能发挥作用，仅基于数量有限的 DNA 序列，这些序列在种水平上往往不适用，在具有地理分布广泛的、来自困难分类群的重复样本方面的测试不佳，并且忽略了在定义物种方面的实质性实际和理论问题。
