Identification of Schisandra chinensis Seeds and Exclusion of Common Adulterants by Allele-Specific PCR Based on ITS2 Sequences.

Background: In terms of medicinal material market and seed sources, Schisandra sphenanthera Rehd.et Wils. is often misused as Schisandra chinensis (Turcz.) Baill. Although the Chinese Pharmacopoeia makes a distinction at the medicinal material level, there is no reliable identification method for seeds. The existing approach still relies on traditional morphology, which requires rich experience.

Objectives: This study aims to fill this gap and enable quality control at the source level.

Material and methods: A neighbor-joining (NJ) tree based on the ITS2 gene was constructed to analyze species genetic relationships and find SNP site for S. chinensis. Primers targeting the SNP site were used in an allele-specific PCR system, whose sensitivity was tested with different amounts of DNA and further validated by commercial samples.

Results: The NJ tree showed that S. chinensis clustered into a single strand, clearly separated from other related species. When the primers were applied to the allele-specific PCR, a diagnostic 273 bp band was amplified specifically in S. chinensis seeds, with no cross-reactivity observed. This assay system exhibited high sensitivity, detecting as little as 0.5 ng of genomic DNA, and was validated by commercial samples, suggesting its accuracy, reproducibility, and practical applicability.

Conclusion: This method is an ideal tool for large-scale seed authentication of S. chinensis due to its high efficiency, precision, and operational simplicity. Our research contributes to quality control throughout the supply chain by ensuring the purity of the seeds at the earliest stages of cultivation, and also promotes the standardized production of this valuable medicinal resource.