Discrimination of Curcuma species from Asia using intron length polymorphism markers in genes encoding diketide-CoA synthase and curcumin synthase.

Recently, Curcuma rhizome-related foods with claimed health benefits have been used worldwide; however, correct identification and quality assessment have not been conducted. Due to the wide distribution and morphological similarities of Curcuma species, the classification of some species is debated and nomenclature is inconsistent among countries. In this study, to elucidate specific molecular markers of medicinally used Curcuma species in Asia, and to solve the confusion on the reported botanical origin of crude drugs, molecular analysis based on the intron length polymorphism (ILP) in genes encoding diketide-CoA synthase and curcumin synthase and the trnK intron sequences was performed using 59 plant specimens and 42 crude drug samples from 13 Curcuma species, obtained from Asian countries. The ILP patterns of the respective species from both plant specimens and crude drug samples revealed high consistency in C. aromatica, C. zedoaria, C. phaeocaulis, C. aeruginosa, C. wenyujin, and C. zanthorrhiza, but showed intraspecies polymorphism in C. longa, C. kwangsiensis, C. amada, C. mangga and C. comosa. The C. longa specimens and samples were separated into three subgroups which were highly consistent with their geographical origins. Based on the ILP markers and the trnK intron sequences, the botanical origins of "Khamin oi" from Thailand were correctly determined to be C. longa or a hybrid between C. longa and other species, and "Wan narn kum" from Thailand and "Kasturi manjal" from India were correctly determined to be C. zanthorrhiza.