Comparison on DNA barcodes of nuclear and chloroplast gene fragments in Rehmannia Libosch. ex Fisch. et Mey. (Rehmanniaceae) / 中草药

ABSTRACT

Objective: To compare the usage of single-copy nuclear genes (SCNGs), chloroplast gene fragments and internal transcribed spacer (ITS) as DNA barcodes in plants of Rehmannia Libosch. ex Fisch. et Mey. and elucidate the interspecific relationships in the genus. Methods: Distance and tree-based methods were performed to analyze 12 SCNGs, six cpDNA regions, and ITS fragment in 13 populations of Rehmannia Libosch. ex Fisch. et Mey. Neighbor-joining tree was constructed to investigate the relationships among the species. Results: CpDNA regions (matK and rbcL) and SCNGs had lower identification rates than others, especially ITS. Multiple DNA barcodes combination would be helpful to improve the species identification rate. The NJ tree indicated that R. glutinosa and R. solanifolia were clustered together, other species in the genus were monophyletic, and R. piasezkii was the basal group. Conclusion: ITS should be used as the core barcode in the genus while psbA-trnH, trnL-F, trnM-V, and trnS-G would be considered as the candidates, and nuclear genes R255 and R257 might be utilized as unique barcode for the identification of R. glutinosa. The origin of tetraploid species (R. glutinosa and R. solanifolia) still remains unknown and further works should be done to solve the question.