| Summary: | 碩士 === 國立中興大學 === 植物學系 === 87 === 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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