Establishment of ITS-Derived Species-Specific PCR Assay Method for Discriminating Herbal Medicine Descurainiae Semen from Its Commercial Adulterants

Accurate authentication of herbal medicine Descurainiae Semen, the tiny seeds of <i>Descurainia sophia</i>, is challenging due to their morphological similarity to various adulterants. To develop a precise and reliable molecular identification method, we conducted comparative analyses of rDNA-ITS sequences using <i>D. sophia</i> and five adulterant species and subsequently developed species-specific sequence-characterized amplified region (SCAR) markers. The discriminatory power and detection limits of these markers were evaluated using serially diluted genomic DNA from each species and commercially available Descurainiae Semen, respectively. The SCAR markers developed in this study enabled the detection of adulterant contamination at levels as low as 0.01-1%. Among several potential adulterants tested using 17 herbal medicines, <i>Erysimum macilentum</i> was found to be the most common adulterant in commercial products, with a ratio of 88%. The SCAR-PCR assay established in this study provides a rapid and accurate tool for identifying <i>D. sophia</i> and illegal adulterants at the species level and at very low contamination levels, thereby supporting improved quality control and enhancing consumer confidence in the herbal medicine industry.