DNA BARCODING IN TAXONOMY

DNA barcoding is a reliable molecular technique for the rapid and precise identification of biological species, overcoming the limitations of conventional morphology-based taxonomy. The method utilizes short, standardized DNA regions that exhibit sufficient interspecific variation while remaining conserved within species. Since its debut in 2003, DNA barcoding has significantly advanced taxonomy, biodiversity assessment, conservation biology and evolutionary studies. Despite the fact that the mitochondrial cytochrome c oxidase subunit I (COI) gene functions as the standard barcode for animals, plant and fungal barcoding relies on markers from nuclear and chloroplast genomes. In plants, rbcL and matK have been established as core barcode loci, supported by supplementary areas like ITS and trnH-psbA for enhanced species resolution. The internal transcribed spacer (ITS) region of the nuclear ribosome in fungus is universally acknowledged as the main barcode, with additional markers including LSU, SSU and protein-coding genes aiding taxonomic refinement. This chapter outlines the principles of DNA barcoding, the concept of the barcoding gap, methodological approaches, and the role of global initiatives and databases. Applications are demonstrated through SKUAST-based case studies on medicinal, nutritional and aquatic plant species, emphasizing the importance of DNA barcoding in species authentication, biodiversity monitoring and conservation strategies.