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Nepentheceae, the most prominent carnivorous family in the Caryophyllales order, comprises the Nepenthes genus, which has modified leaf trap characteristics. Although most Nepenthes species have unique morphologies, their vegetative stages are identical, making identification based on morphology difficult. DNA barcoding is seen as a potential tool for plant identification, with small DNA segments amplified for species identification. In this study, three barcode loci; ribulose-bisphosphate carboxylase ( rbc L), intergenic spacer 1 (ITS1) and intergenic spacer 2 (ITS2) and the usefulness of the ITS1 and ITS2 secondary structure for the molecular identification of Nepenthes species were investigated. An analysis of barcodes was conducted using BLASTn, pairwise genetic distance and diversity, followed by secondary structure prediction. The findings reveal that PCR and sequencing were both 100% successful. The present study showed the successful amplification of all targeted DNA barcodes at different sizes. Among the three barcodes, rbc L was the least efficient as a DNA barcode compared to ITS1 and ITS2. The ITS1 nucleotide analysis revealed that the ITS1 barcode had more variations compared to ITS2. The mean genetic distance (K2P) between them was higher for interspecies compared to intraspecies. The results showed that the DNA barcoding gap existed among Nepenthes species, and differences in the secondary structure distinguish the Nepenthes . The secondary structure generated in this study was found to successfully discriminate between the Nepenthes species, leading to enhanced resolutions.

The present study demonstrated High Resolution Melting (HRM) analysis combined with DNA barcode (Bar-HRM) as a fast and highly sensitive technique for detecting adulterants in Eurycoma longifolia commercial herbal products. Targeting the DNA barcoding of the chloroplastic region-ribulose biphosphate carboxylase large chain (rbcL) and the nuclear ribosomal region- internal transcribed spacer 2 (ITS2), PCR amplification and HRM analysis using saturated Eva green dye as the source of fluorescence signals, was accomplished by employing a real-time cycler. The results were further validated by sequencing to identify unknown sequence from Genbank database and to generate phylogenetic tree using neighbour joint (NJ) analysis. Both of the DNA markers exhibited a distinguishable melting temperature and shape of the normalised curve between the reference and the adulterants. In the case of species identification, ITS2 was more successful in differentiating between species. Additionally, detection of admixture sample containing small traces of targeted E. longifolia DNA ( w / v ) can be detected as low as 5% for rbcL and less than 1% for ITS2, proving the sensitivity and versatility of the HRM analysis. In conclusion, the Bar-HRM analysis is a fast and reliable technique that can effectively detect adulterants in herbal products. Therefore, this will be beneficial for regulatory agencies in order to regulate food safety issues.