Background: Smithia conferta Sm. is an annual herb widely used in Indian traditional medical practice and commonly known as "Lakshman booti" in Sanskrit. Morphological resemblance among the species of genus Smithia Aiton. leads to inaccurate identification and adulteration. This causes inconsistent therapeutic effects and also affects the quality of herbal medicine.
Aim: This study aimed to generate potential barcode for authentication of S. conferta and its adulterants through DNA barcoding technique.
Materials and methods: Genomic DNA extracted from S. conferta and its adulterants was used as templates for polymerase chain reaction amplification of the barcoding regions. The amplicons were directed for sequencing, and species identification was conducted using BLASTn and unweighted pair-group method with arithmetic mean trees. In addition, the secondary structures of internal transcribed spacer (ITS) 2 region were predicted.
Results: The nucleotide sequence of ITS provides species-specific single nucleotide polymorphisms and sequence divergence (22%) than psbA-trnH (10.9%) and rbcL (3.1%) sequences. The ITS barcode indicates that S. conferta and Smithia sensitiva are closely related compared to other species.
Conclusion: ITS is the most applicable barcode for molecular authentication of S. conferta, and further chloroplast barcodes should be tested for phylogenetic analysis of genus Smithia.
Summary: The present investigation is the first effort of utilization of DNA barcode for molecular authentication of S. conferta and its adulterants. Also, this study expanded the application of the ITS2 sequence data in the authentication. The ITS has been proved as a potential and reliable candidate barcode for the authentication of S. conferta. Abbreviations used: BLASTn: Basic Local Alignment Search Tool for Nucleotide; MEGA: Molecular Evolutionary Genetic Analysis; EMBL: European Molecular Biology Laboratory; psbA-trnH: Photosystem II protein D1- stuctural RNA: His tRNA gene; rbcL: Ribulose 1,5 bi-phosphate carboxylase/oxygenase large subunit gene.
Keywords: DNA barcode; Smithia; internal transcribed spacer; single nucleotide polymorphism.