Potential use of ITS2 and matK as a Two-Locus DNA Barcode for Identification of Vicia Species

We investigated the species discriminatory efficiency of the proposed plant barcoding loci ITS2 and matK in Vicia species. In 2011, China Plant BOL Group proposed the addition of nuclear ITS2 to matK be accepted as a 2-locus DNA barcode to classify plant species. The matK region was chosen as a DNA barcode because of its effective species discriminating power, high quality sequence recovery, and easy experimental analysis. Integration of matK sequences into Vicia phylogeny could improve phylogenetic reconstruction of this species. To assess the ability of barcoding loci to resolve Vicia species, we sampled 36 of the taxonomically best known groups in the genus. Topologies of the phylogenetic trees based on ITS2 and matK analyses were similar but a few accessions were placed into distant phylogenetic groups. Neither ITS2 nor matK analyses alone could discriminate some closely related Vicia species. Thus, we have proposed a concatenated data approach to increase the resolving power of ITS2 and used matK as an additional tool for phylogenetic analysis in Vicia because characterization of the nucleotide sequences of the matK region was easier to recover and more cost-effective than those of the ITS region.