Internal transcribed spacer (ITS): The powerful DNA barcode and phylogenetic marker for successful authentication of Withania somnifera

Understanding the evolutionary history of plants and accurately identifying biologically important species and their families is crucial for the herbal and Ayurvedic industries. The genetic approach by DNA barcoding plays a pivotal role in accurate species identification, authentication and quality control. Due to various therapeutic properties, Withania somnifera has been used worldwide in traditional systems of medicine for centuries including Ayurveda and Unani. The increasing demand for W. somnifera products has led to concerns regarding the authenticity and quality of commercial herbal preparations. However, adulteration become major trouble for users and industry for safety reasons and authentication of the plant with proper DNA marker is a major concern.

DNA barcoding techniques and Phylogenetic analysis were employed to authenticate W. somnifera plant species using universal genetic markers. The markers were PCR amplified, sequenced and analyzed using BLAST-based and phylogeny-based identification methods.

The BLAST result shows the percent identity (PI) of ITS1, ITS2, trnK, atpB, rbcL and matK was 100%, 100%, 100%, 97.59%, 100 and 99.20% respectively with the NCBI reference sequence. However, ITS1 and ITS2 show the maximum sequence similarity with W. somnifera of NCBI data. Phylogenetic analysis using NCBI data further supports the role of ITS in the discrimination of W. somnifera from closely related species.

Therefore, the ITS gene may be considered promising a candidate for DNA barcoding for discrimination of W. somnifera from other species, its authentication and quality control.