Development of a Spot Test (ST) Based on the Nucleic Acid Amplification Test (NAAT) for Ginseng Species Authentication

Abstract

It is very challenging to distinguish between Panax ginseng (P. ginseng) and Panax quinquefolius (P. quinquefolius) based on their physical appearances. Therefore, a molecular test that can be performed in commercial settings is needed to address this challenge. We have selected a locus containing a single nucleotide polymorphism (SNP) site in the Dammarendiol-II Synthase (DS) gene to differentiate between P. ginseng and P. quinquefolius. An isothermal nucleic acid amplification test (NAAT) developed previously was adapted and used on a spot test (ST) format consisting of a sample pad, a nitrocellulose membrane, and an adsorbent pad. An ST with a colorimetric detection method has been developed with visual detection based on 20-nm gold nanoparticles. The presence of the target DNA will generate a red color signal, which is visible to the naked eye. The assay comprises the capture probes, constructed based on the DS gene of ginseng, and the ends of the probe sequences sit on the SNP site for the P. ginseng and P. quinquefolius sequences; the detection probe employed in the assay is tagged with gold. The NAAT amplifies the extracted plant genomic samples and enhances the detection of specific SNPs. This NAAT technique was used to authenticate two ginseng root samples, showing greater specificity ratios than our previous work.