作者：黃勝忠　蔡奇助　易美 秀

　　 利用 PCR-amplified RFLP 分析核糖體核酸 (rDNA) 內轉錄間隔區 (internal transcribed spacer, ITS) ，來鑑定 24 個文心蘭亞族 (Oncidiinae) 品種。分析樣本 ITS 區域之 DNA 利用 PCR 複製後，以 10 種限制酶切割，共產生 166 個 DNA 標誌，其中有 159 個標誌在品種間具有多型性，可供品種鑑別依據。經群叢分析 (clustering analysis) 後，可將 24 個文心蘭品種分成四群及兩個各自成一群的品種。由樹狀關係圖發現，文心蘭節 (section Oncidium) 與文心蘭屬 (genus Oncidium) 內其它成員具有明顯區別，此結果支持文心蘭節 ( 箭葉型文心蘭 ) 有別於文心蘭屬內其它節 ( 薄葉型文心蘭 ) ，可以自成一新的屬。另外，檢視 DNA 電泳條帶型，也發現雜交品種具有加成性的 DNA 條帶型，亦即文心蘭雜交品種個體內之 ITS 重複序列具有異質性。本研究在文心蘭亞族雜交品種所發現之加成性 DNA 條帶型，可視為一有用的分子標誌，供未來鑑別文心蘭品種及品種保護之用。

關鍵字： 文心蘭、內轉錄間隔區、分子標誌、品種鑑定、異質性。

　　The internal transcribed spacer (ITS) of ribosomal DNA (rDNA) could be used as a marker to identify genetic differences among 24 accessions of species and hybrids of the Oncidiinae based on PCR-amplified RFLP analysis. The ITS region of rDNA in 24 respective accessions of the Oncidiinae was amplified by a pair of complementary primers to conserved regions at 3’ end of 17S and 5’ end of 25S of rRNA genes. DNA fragments of ITS were digested with ten restriction enzymes and then subjected to electrophoresis. Among the 166 bands that appeared, 159 bands were polymorphic. From the cluster analysis on the pattern of band distribution in all samples, four major groups and two individual clusters not belonging to any of the four groups were identified based on molecular data. Section Oncidium, belonging to genus Oncidium in traditional view, was shown to separate from other accessions of genus Oncidium. In addition, additive DNA band pattern was shown within individuals of hybrid cultivars. In other words, sequence heterogeneity of ITS repeat family was shown within individuals of hybrid cultivars. In short, a technology to identify Oncidiinae cultivars and to protect the right of plant breeders was shown in present study.