A comparison of nrDNA internal transcribed spacer (ITS) loci for phylogenetic inference and authentication among Cinnamomum osmophloeum and related species in Taiwan
Cinnamomum osmophloeum, an indigenous species of Taiwan, can be utilized for valuable products such as a food, a spice and a traditional Chinese medicine. This study compares the ribosomal DNA (nr DNA) internal transcribed spacer (ITS) sequence of C. osmophloeum to that of several other species with similar external morphology, such as Cinnamomum burmannii, Cinnamomum insularimontanum, Cinnamomum macrostemon and Cinnamomum subavenium. Phylogeny of ITS sequences shows that C. osmophloeum is more closely related to C. burmannii than the other species, while C. insularimontanum, C. macrostemon, and C. subavenium are phylogenetically relevant to each other. By comparing ITS sequence between C. osmophloeum and C. burmannii, specific primers were designed for the multiplex-PCR to differentiate them. Based on ITS sequence differences, all tested Cinnamomum spp. can be properly authenticated. A 125 bp band specific for C. osmophloeum and a 204-bp C. burmannii-specific band were successfully amplified by polymerase chain reaction (PCR) using the respective primers described above. The two species then can be identified at the molecular level according to the sizes of their respective PCR products as determined by gel electrophoresis.
Key words: Cinnamomum osmophloeum, internal transcribed spacer (ITS), phylogenetic, multiplex- polymerase chain reaction (PCR).