利用DNA分子标志鉴别台湾茶树品种及评估种原之遗传歧异性

爲評估台灣茶樹種原之遺傳歧異性,本硏究由100條ISSR引子中篩選出12條可産生多型性條帶明顯的引子,這些引子共可産生67個的多型性條帶罁恳环N原之分子標誌數據進行UPGMA法分群分析結果,可將台灣133個茶樹種原區分成六大群,包括油茶群、赤芽山茶群、野生茶樹群、大葉變種與小葉變種混合群、大葉、小葉及大葉、小葉雜交種混合群及小葉變種群。而主成分向量分析的結果與利用群聚分析得到的親緣關係樹形圖結果相符合。台灣茶樹種原高比例的遺傳歧異度是由台灣的野生茶樹所貢獻,部分重要栽培種間的相似性仍極高。爲了探討制茶過程對分子級品種鑒定之影響及DNA分子標誌應用于成茶品種鑒定之可行性,本硏究分析不同發酵程度的茶類,在制茶過程中對DNA質量之影響,試驗結果顯示高溫殺菁過程嚴重造成成茶DNA的降解。利用各種類別成茶與新鮮茶葉(對照)所抽取之DNA樣品進行PCR擴增反應,結果發現分子量小於1,000bp的ISSRDNA條帶表現較穩定。

Using ISSR DNA Markers to Identify Varieties and Evaluate Genetic Diversity of Tea Germplasm in Taiwan

To evaluate the genetic diversity of tea germplasm, twelve ISSR primers amplifying a total of 67 obvious and polymorphic bands were prescreened from 100 primers. The ISSR DNA fingerprints of each germplasm were used to analyze genetic diversity. According to UPGMA method, 133 tea gerplasm could be divided into 6 groups: including C. tenuifolia group, Chyh-Ya-Sun-Cha group, wild tea plant group, var. assamica and var. sinensis group, var. assamica with var. sinensis and their hybrid group and var. sinensis group. Similar grouping result was found in the principal coordination components analysis and the cluster diagram. Despite the high genetic diversity among germplasm, high percentage of it was contributed by the wild tea plants, and some important cultivars had high degree of similarity. To study the feasibility of applying DNA markers in variety identification for made tea, the isolated DNA quality of samples from various procedures of different fermented tea was analyzed. The result indicated that high temperature treatment at panning step resulted in dramatic DNA degradation. For all kinds of made tea, ISSR DNA markers less than 1,000 bp were stably amplified. ISSR DNA bands less than 1,000 bp were steadily detected for the processed tea samples after 1, 6, or 18 months of storage.