Evaluation of 11 single-locus and seven multilocus DNA barcodes in Lamium L. (Lamiaceae)

The aim of this work was to evaluate the suitability of selected DNA regions in the barcoding of plants, based on the species belonging to the genus Lamium (Lamiaceae). For this purpose, nine chloroplast barcodes, that is, accD, matK, rbcL, rpoA, rpoB, rpoC1, rpoC2, trnH-psbA, trnL-trnF, as well as ITS nuclear region, and intron of mitochondrial nad5 gene were tested. Among the single-locus barcodes, most effective in the identification of Lamium species was the trnH-psbA spacer and matK gene. The high level of variability and resolving power was also observed in the case of rpoA and rpoC2 genes. Despite the high interspecies variability of ITS region, it turned out to be inapplicable in Lamium identification. An important disadvantage of ITS as a barcode is a limitation of its use in polyploid plants, samples contaminated with fungal material or samples with partially degraded DNA. We have also evaluated five-two-locus and two-three-locus barcode regions created from a combination of most effective single loci. The best-performing barcode combinations were matK + trnH-psbA and matK + rpoA. Both of them had equally high discriminative power to identify Lamium species.