Phylogenetic Relationship Investigation of Some Medicinal Plants Using Nuclear ITS Barcodes

DNA barcoding is a straightforward strategy that uses short orthologous genetic sequences and standard genomes to specify species. This technique has the capability of molecular identification, detection of living species and discovery of unfamiliar species, preservation of genetic resources, identification of genetic diversity and phylogenetic characterization, and testing of differentiated existing plant species, as well as assuring the safety and efficacy of pharmaceuticals. In this experiment, the allelic diversity of 7 classes of medicinal plants viz. fenugreek, local fenugreek, waybread, cumin, flax, fixweed and sesame, from Ilam and Khuzestan provinces; west and south of Iran, respectively, was carried out employing this technique and with the aid of primers designed and established on ITS nuclear barcodes (ITS1 and ITS2 genes). The results indicated that there was a great difference between the fragments and the duplicated sequences of ITS1 and ITS2 barcodes in different samples. Moreover, the nucleotide searching of the sequences showed that there was a very high similarity (more than 90%) between the acquired sequences and their equivalents in the NCBI database. The nucleotide sequence of the ITS1 gene of fenugreek showed the highest similarity (78.2%) with native fenugreek. Regarding the ITS1 gene, more amount of G~C content than A~T was observed and, in the waybread plants the amount of C base was higher than G, and for native fenugreek, the amount of A~T content was more than G~C. In the case of ITS2 position, in all examined samples (except the fixweed plant, which had higher A~T), the values ​​of G~C content were higher than A~T. The output of the cluster analysis with the UPGMA algorithm showed the precise grouping and separation of species and the high potential of these sequences using the barcode system in the phylogenetic evaluation of medicinal plant species.