核糖體內轉錄區間第二段部分序列應用在條碼土肉桂樣品之研究   全文下載

DNA Barcoding Cinnamomum osmophloeum Kaneh. Based on the Partial Non-Coding ITS2 Region of Ribosomal Genes

本文探討將核糖體內轉錄區間第二段序列應用於條碼原生種土肉桂樣品之可行性。本實驗萃取台灣地區七種不同地理品系的土肉桂葉片精油，鑑定其組成份，並比較不同土肉桂地理品系間核糖體內轉錄區間的第二段序列之差異。各地理品系的土肉桂葉片精油經氣相層析──質譜儀分析鑑定與群團分析後，依組成分分類與其相對含量可分為六種化學品系：桂皮醛型、枷羅木醇型、樟腦型、桂皮醛－－桂皮乙酸酯型、桂皮乙酸酯型與混合型。系統演化樹是利用核糖體內轉錄區間的部分第二段序列，根據UPGMA法的聚類方式對不同地理品系的土肉桂所構建的。實驗結果顯示：雖然這些土肉桂代表了六種不同的化學型，但核糖體內轉錄區間的部分第二段序列在不同化學型品系的土肉桂樣品間卻沒有差異。顯示利用核糖體內轉錄區間的部分第二段序列可以成功的條碼本土原生的土肉桂，但若要能同時成功的鑑別不同化學型的土肉桂，則必須搭配使用其它基因的DNA鑑定技術。本實驗建立的DNA條碼技術可以推廣應用於條碼台灣地區植物的研究。

This paper investigated the DNA barcoding of indigenous cinnamon. The essential oil composition of leaves and the partial non-coding internal transcribed spacer (ITS2) region of ribosomal genes from indigenous cinnamon plants (Cinnamomum osmo-phloeum Kaneh.) were investigated. Leaf essential oils from seven geographical strains of C. osmophloeum Kaneh. were obtained by hydrodistillation and characterized by gas chromatography-mass spectrometry. Six chemotypes, including cinnamalde-hyde, cinnamaldehyde/cinnamyl acetate, cinnamyl acetate, linalool, camphor and mixed, were identified. Seven representative geographical strains were further used to study their genetic diversity based on the partial ITS2 region using PCR amplification and DNA sequencing to evaluate the region’s use in the application of DNA barcoding C. osmophloeum Kaneh. A phylogenetic tree was constructed using UPGMA clustering method. Our results indicate that the partial ITS2 nucleotide sequences for all seven geographical strains are identical and not correlated with essential oil composition. The partial ITS2 sequences is sufficient for barcoding C. osmophloeum Kaneh., while that additional genes will need to be analyzed to identify samples of various chemotypes. We believe that this partial ITS2 locus serves as a good starting point for large-scale testing of DNA barcoding of other plant species across Taiwan.