Testing DNA barcodes in closely related species of <I>Curcuma</I> (Zingiberaceae) from Myanmar and China

Abstract

The genus Curcuma L. is commonly used as spices, medicines, dyes and ornamentals. Owing to its economic significance and lack of clear-cut morphological differences between species, this genus is an ideal case for developing DNA barcodes. In the present study, four chloroplast DNA regions (matK, rbcL, trnH-psbA, trnL-F) and one nuclear region (ITS2) were generated for forty-four Curcuma species and five species from closely related genera, represented by 96 samples. PCR amplification success rate, intra- and inter-specific genetic distance variation, and the correct identification percentage were taken into account to assess candidate barcode regions. PCR and sequence success rate were high in matK (89.7%), rbcL (100%), trnH-psbA (100%), trnL-F (95.7%) and ITS2 (82.6%) regions. The results further showed that four candidate chloroplast barcoding regions (matK, rbcL, trnH-psbA and trnL-F) yield no barcode gaps, indicating that the genus Curcuma represents a challenging group for DNA barcoding. The ITS2 region presented large interspecific variation, and provided the highest correct identification rates (46.7%) based on BLASTClust method among the five regions. However, the ITS2 only provided 7.9% based on NJ tree method. An increase in discriminatory power needs the development of more variable markers. This article is protected by copyright. All rights reserved.