Molecular authentication of Gynostemma pentaphyllum through development and application of random amplification polymorphic DNA sequence-characterized amplified region marker.

Due to the morphological similarities of aerial parts, it is difficult to distinguish Gynostemma pentaphyllum from Cayratia japonica, which is usually an adulterant of the former. To develop a reliable method for the identification and authentication of G. pentaphyllum, a combination of random amplification polymorphic DNA (RAPD) technique with sequence-characterized amplified region (SCAR) markers was studied. Twenty-five samples of G. pentaphyllum and two samples of C. japonica were collected from different regions in Guangxi or bought from different provinces in China. Through the RAPD analysis, significant genetic polymorphism was observed among the intraspecies samples of G. pentaphyllum. Furthermore, a specific marker, J-750, was obtained for authentication. Therefore, the SCAR marker for G. pentaphyllum (359 bp) was developed from the RAPD amplicon. With PCR amplification using the SCAR primers, a specific band of 359 bp was distinctly visible for all tested samples of G. pentaphyllum, but was absent in the samples of C. japonica. Furthermore, the results revealed that the SCAR marker was useful for the identification and authentication of G. pentaphyllum irrespective of whether samples were fresh, dry, or of commercial origin. The SCAR marker obtained in this study successfully authenticated G. pentaphyllum through an integrated PCR system containing SCAR and control primer combinations of two pairs. In addition, it was also used for simultaneous discrimination of G. pentaphyllum from C. japonica.