title: Power and limitations of the chloroplast trnL (UAA) intron for plant DNA barcoding.
abstract: DNA barcoding should provide rapid, accurate and automatable species identifications by using a standardized DNA region as a tag. Based on sequences available in GenBank and sequences produced for this study, we evaluated the resolution power of the whole chloroplast trnL (UAA) intron (254-767 bp) and of a shorter fragment of this intron (the P6 loop, 10-143 bp) amplified with highly conserved primers. The main limitation of the whole trnL intron for DNA barcoding remains its relatively low resolution (67.3% of the species from GenBank unambiguously identified). The resolution of the P6 loop is lower (19.5% identified) but remains higher than those of existing alternative systems. The resolution is much higher in specific contexts such as species originating from a single ecosystem, or commonly eaten plants. Despite the relatively low resolution, the whole trnL intron and its P6 loop have many advantages: the primers are highly conserved, and the amplification system is very robust. The P6 loop can even be amplified when using highly degraded DNA from processed food or from permafrost samples, and has the potential to be extensively used in food industry, in forensic science, in diet analyses based on feces and in ancient DNA studies.
authors.affiliation: Laboratoire d'Ecologie Alpine, CNRS UMR 5553, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France. pierre.taberlet@ujf-grenoble.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Taberlet
authors.forename: Eric
authors.initials: E
authors.lastname: Coissac
authors.forename: François
authors.initials: F
authors.lastname: Pompanon
authors.forename: Ludovic
authors.initials: L
authors.lastname: Gielly
authors.forename: Christian
authors.initials: C
authors.lastname: Miquel
authors.forename: Alice
authors.initials: A
authors.lastname: Valentini
authors.forename: Thierry
authors.initials: T
authors.lastname: Vermat
authors.forename: Gérard
authors.initials: G
authors.lastname: Corthier
authors.forename: Christian
authors.initials: C
authors.lastname: Brochmann
authors.forename: Eske
authors.initials: E
authors.lastname: Willerslev
mesh_terms: D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D018742:DNA, Chloroplast / Q000737:chemistry*; D030561:Databases, Nucleic Acid; D007438:Introns; D008969:Molecular Sequence Data; D010944:Plants / Q000145:classification* / Q000235:genetics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: D017931:DNA Primers; D018742:DNA, Chloroplast