The Potential Of RBCL Region As Dna Barcode For Nine Species Of Malaysian Herbs

Abstract

DNA barcoding is an inexpensive species identification process that can be conducted even by non-taxonomist using specific DNA barcodes fragments. DNA barcodes are short fragments (~800 base pairs) of gene sequences that evolve fast enough to differentiate species, but have flanking regions that are sufficiently conserved to enable barcode regions to be serviced by universal primers (Rubinoff et al., 2006). There are at least 1200 species of plants in Malaysia that have been found to contain potential pharmaceutical values (Khatijah, 2006). Herbal plants throughout Malaysia have always been identified by taxonomists. Following elaborate standard procedures, taxonomists rely on morphological traits as keys for identification. A certain specimen that lacks morphological traits can also be difficult to be identified even by experienced taxonomists. DNA barcoding may be applied in this matter to assist in the species identification process (Gregory, 2005). Due to high demand of certain herbal medicines, adulteration or substitution of herbal drugs regularly occurs. It was reported that a certain irresponsible party used rubber wood that was pre-treated with quinine to give it a bitter taste that is similar to Eurycoma longifolia or tongkat ali (Khatijah, 2006). Taxonomists however face difficulties in identification of processed products. This obstacle can now be overcome by using DNA barcodes (Srirama et al., 2010). In this study, we revealed the potential of rbcL region as DNA barcode for 9 herbal species sampled in Malaysia. In the end, the objective of this research is to develop DNA barcode(s) for specific families of Malaysian herbs for archiving purposes by using several potential existing barcoding candidates such as matK, rbcL, trnH-psbA, rpoC1, rpoB, ycf5 and ITS. The long term aim of this research is to develop a quick one step detection kit for phytopharmaceutical products. A total of 642 nucleotide sequences were obtained from alignment of rbcL gene from the 9 samples where 482 are conserved sites while the other 160 are variable sites. nBAST search for species level identification was also successful for 5 out of the 9 tested species. As a conclusion, this study shows that the analysis of partial rbcL gene can be successfully carried out to determine the genetic relatedness among different species of Malaysian herbs