Identification of two chemotypes of Pogostemon cablin (Blanco) Benth. through DNA barcodes.

Pogostemon cablin (Blanco) Benth. is an important medicinal plant in Traditional Chinese Medicine (TCM). Because of differences in the chemical composition, this species has been classified into two major chemotypes, i. e. the patchouliol-type and the pogostone-type; however, no quick and effective method is presently available for the precise identification of these two chemotypes. DNA barcoding, using a standardized DNA fragment, is a promising molecular diagnostic method for species identification. We have established a reliable and quick method for the identification of the P. cablin chemotypes. Of five potential barcodes [rbcL, psbA-trnH, rpoB, ITS (internal transcibed spacer), and ndhJ], tested among 103 samples, ITS was the best candidate, as comparative studies between patchouliol-type and pogostone-type P. cablin revealed that ITS had more variable regions among these five barcodes. We suggest that ITS can serve as the most suitable barcode for differentiating between the chemotypes of P. cablin.