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An assessment of genetic diversity and relationship in cultivated tea clones and native wild tea in Taiwan using RAPD and ISSR markers
|關鍵字:||Tea plant;茶樹;genetic diversity;relationship;RAPD;ISSR;遺傳歧異度;親緣關係;逢機擴大多型性核酸;簡單重複序列區間||出版社:||植物學系||摘要:||
茶樹（Camellia sinensis L. (O. Kuntz)）是重要的經濟作物。台灣的茶樹栽培品種主要源自於中國及印度，分佈在台灣山區的野生茶樹未被廣泛的利用與研究。茶樹為多年生異交植物，以形態特徵鑑定品系容易受到環境影響及樹齡影響，且不易判斷品系間親緣關係，而分子性狀具有直接反映遺傳物質的差異不易受環境影響的優點。在本研究中，應用RAPD及ISSR技術分析台灣地區引進的品種，雜交育成的品種和台灣的野生茶樹共三十七個樣本，結果以十二個RAPD引子及六個ISSR引子分別得到五十三及五十六個多型性條帶。RAPD分子標誌除了大南灣白毛猴及黑毛猴不能區分外能區分其他的樣本，而ISSR分子標誌能區分所有的樣本。自RAPD及ISSR分子性狀的歸群分析及主座標分析的結果得知，各栽培品種大致依照發源地及分類地位而分群。中國與阿薩姆變種的雜交後裔，與中國變種的品種被歸在一起。而台灣的野生茶樹的分子性狀偏向於阿薩姆變種，且野生茶樹樣本間的歧異度相當大。依歸群結果分群進行Shannon歧異度及AMOVA分析的結果均指出群內變方成分大於群間的變方成分，與前人研究相符。比較RAPD及ISSR相似度矩陣，兩矩陣間相關係數為0.81，兩種技術分析的結果大致吻合。以品系的區分能力以及群內歧異度做比較，顯示ISSR技術具有較高的靈敏度，及較快之演化速率，ISSR技術較RAPD技術更適於應用於近緣的分類群之研究上。
Camellia sinensis is an important beverage crop in Taiwan. The majority of tea clones were introduced from China and India. Besides cultivated varieties, the native wild tea is distributed in some of the central and southern mountains. Tea is an outbreeding species. The clone identification is traditionally based on plant shape, leaf shape, young leaf type, and fruit shape. These morphological characters are under the influences of age and environmental factors. Thus clone identification and the study of the relationships among clones based on morphological characters alone might become difficult. The advantages of molecular markers are that they are less influenced by environmental factors and they reflect directly the genetic materials. In the present study, a total of 37 samples were studied using RAPD and ISSR markeras. The samples included 21 clones of China tea, 3 clones of Assam tea, 7 clones developed from hybrids between China tea and Assam tea, and 6 accessions of native wild tea. Twelve RAPD primers and six ISSR primers were used for amplification. A total of 53 RAPD markers and 56 ISSR markers that were polymorphic and reproducible were used in the analysis. The samples can be identified based on RAPD bands except ''Hei-mao-hu'' and ''Dai-nan-uan-pei-mao-hu'' that have identical band profile. These two clones can be idendified based on ISSR band profile. The results of cluster analysis and principal coordinate analysis showed that three groups could be recognized. The first group consisted of all cultivars of China tea and those cultivars developed in Taiwan from hybridization and selection. The second group consisted of all three cultivars of Assam tea while the third group consisted of samples of native wild tea. The groupings were in general consistent with the regions of origin and the classification positions. The native wild tea has closer relation with Assam tea. A large diversity was found among samples of the native wild tea. Shannon''s diversity analysis and AMOVA revealed that the variance component within groups was larger than the variance component among groups. The correlation coefficient between RAPD and ISSR similarity matrices was 0.82, indicating good congruence between the results of the two molecular markers. However, ISSR is more sensitive for clone identification. The evolution rate of ISSR is faster than that of RAPD. ISSR marker is more suitable than RAPD for studying the units with close relationships.
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