台灣特有種土肉桂(Cinnamomum osmophloeum Kaneh.)屬樟科(Lauraceae)，常綠中喬木，葉背具白粉，三出脈。由於土肉桂不僅可做為中藥亦可做為香料使用，因此在市場上有相當大的需求。傳統上以型態學或組織學之特徵鑑別植物之效果有限，尤其於苗期可判視之特徵極少，更是難以區分，而傳統之型態鑑別可能造成藥用植物之混用或誤用，因此透過DNA分子標記(molecular marker)技術來對土肉桂加以鑑別。本試驗所使用之73株土肉桂樣株採自林業試驗所蓮華池與中國文化大學華林林場。藉由分析核醣體DNA非編碼區之pITS2 (partial non-coding internal transcribed spacer 2, pITS2)序列以及葉綠體DNA (chloroplast DNA)之trnL-trnF序列，以探討土肉桂之基因歧異度(genetic diversity)與核苷酸序列多型性 (nucleotide polymorphism)。試驗結果顯示，蓮華池土肉桂之基因歧異度較華林林場豐富，多片段排比 (Multiple sequence alignments) 之結果顯示，相較於trnL intron與trnL-trnF IGS，pITS2具有較高之核苷酸序列多型性。系統發育樹 (phylogenetic trees) 之分析結果顯示，利用最大簡約法 (maximum parsimony, MP) 與鄰接法(neighbor-joining, NJ) 可成功地將蓮華池、華林林場以及GenBank與EMBL資料庫之肉桂類植物分群。我們認為藉由pITS2之序列多型性可作為基因上的分類與建立DNA序列資料庫，便於未來土肉桂基原 (gene resource) 鑑定之用。利用pITS2 DNA序列，可用來作為土肉桂種內及種間之鑑別，亦說明了pITS2具有基原鑑定的價值。
Cinnamomum osmophloeum Kaneh. (CO) belongs to the Lauraceae family. It is considerable market demand, because not only can be used as traditional Chinese edicine but also as a spice. Traditionally, morphological or histological identification of plants using characteristics of the effect is limited. In particular, the characteristics can be distinguished in the seedlings stage are less, so that difficult to distinguish. And type of identification may lead to mixing or misuse of medicinal plants. Therefore, we used DNA molecular marker technology to identify Cinnamomum osmophloeum Kaneh. This study attempts to identify the gene resources of Cinnamomum osmophloeum Kaneh. by analyzing the nucleotide sequences of the partial non-coding internal transcribed spacer 2 (pITS2) of the ribosomal DNA and the trnL-trnF chloroplast genome. Seventy-three geographical strains of CO, preserved in the Lien Hua-Chin Research Center of the Forestry Research Institute and the Hua-Lin Forestry Center of Chinese Culture University, were collected and analyzed by PCR amplification and DNA sequencing to study the genetic diversity and nucleotide sequence polymorphisms of the tested specimens. Our results allowed us to accurately identify the lineage of CO and to conclude that the strains belonging to the Lien Hua-Chin Research Center had much higher genetic diversity than those preserved in the Hua-Lin Forestry Center. Multiple sequence alignments demonstrated that the variability of the nucleotide sequence polymorphisms for the pITS2 region was higher than those of the trnL intron and trnL-trnF IGS regions among the 73 tested specimens of CO. Cluster analyses, using the neighbor-joining and maximum parsimony methods, for the 73 tested geographical strains of CO and species of Cinnamomum registered in the GenBank and EMBL databases were performed to demonstrate the genus and species distribution of the samples. Here, we describe the use of pITS2 polymorphisms as a genetic classifier and report the establishment of a DNA sequence database for CO gene resource identification. The sequence database described in this study can be used to identify CO specimens at the inter- or intra-species level using pITS2 DNA sequences, which illustrates its value in gene resource identification.
