Abstract: In order to select a suitable DNA barcode for accurate identification of Dendrobium officinale, 25 samples of D. officinale and 10 samples of other Dendrobium species were subjected to molecular identification using nine commonly used plant DNA barcodes (ITS2, nad1, matK, ycbL, psbK-psbI, trnL-trnF, trnG-trnS, rbcL and trnH-psbA). The results showed that the versatility of the nine DNA barcodes was strong, with high success rates of amplification and sequencing. The maximum genetic distance within species of rbcL and trnH-psbA was greater than the minimum genetic distance between species, which did not meet the basic requirements for barcodes. Instead, the maximum genetic distance within species of the other barcodes was smaller than the minimum genetic distance between species. The decreasing order of interspecific variation was ITS2 > trnL-trnF > trnG-trnS > psbK-psbI > ycf1b > matK > nad1. ITS2 had the fastest evolution rate and the highest mutation rate (25.1%). The identification rates of ITS2 and trnL-trnF for the Dendrobium samples tested were both 90.1%. It is recommended that ITS2 + trnL-trnF be used for the identification of D. officinale germplasm resources. The results of this study are expected to provide a reference and molecular basis for the identification of D.officinale and its closely related species by using DNA barcoding technology.

Key words: Dendrobium officinale; DNA barcoding; molecular identification; genetic distance