Rapid identification of Curcuma longa and C. aromatica by LAMP

We have developed a novel method for the identification of Curcuma longa and C. aromatica called "loop-mediated isothermal amplification (LAMP)," based on trnK gene sequences. LAMP employs four primers that recognize six regions on the target DNA. Cycling elongation was initiated when the four primers were annealed to the target DNA. Amplifications were detected by measuring turbidity due to the formation of magnesium pyrophosphate. We designed allele-specific primer sets for C. longa and C. aromatica, respectively. LAMP using a primer set for C. longa and total DNA extracted from C. longa rhizome (0.5-10.0 ng) as template was detected up to 70 min. On the other hand, in the reaction using a primer set for C. longa and total DNA from C. aromatica as template, no amplifications were detected. The same tendency could be seen in the reactions using a set of primers for C. aromatica. LAMP enabled not only identification but also detection with high specificity. This rapid, specific, sensitive, and convenient method is expected to be applicable to the identification of the botanical origin of commercially available herbal products.