桶柑遺傳歧異性之分析

The Analysis of Genetic Variation Among Tankan (Citrus tankan Hayata) Accessions

16個營養性狀經群集分析及主成份分析，結果顯示桶柑收集品系具有歧異性。分群結果與果實大小特性相符，群內收集品系間仍有差異存在，但地區性不明顯。主成份分析結果顯示，前三主成份軸共可解釋76.28%的變異量，其中本葉長寬比、翼葉長、每公分葉緣鋸齒數、每公分葉緣油胞數及單位面積油胞數為主要之有效性狀，分群結果與16個性狀的分群結果相類似，可應用於果實大小的早期篩選。本試驗中265個引子具PCR反應產物，平均每個引子可產生6個條帶，其中95%為穩定具再現性之共有條帶，顯示收集品系在遺傳組成上相似性極高；其餘具多型性的條帶（約5%），多不具再現性，顯示DNA層次上差異存在的部分，無法以RAPD方法偵測。以16個營養性狀經群集分析及主成份分析，亦可將桶柑與海梨區分；然而RAPD分析結果，桶柑與海梨PCR產物條帶幾近相同，顯示其遺傳組成的相似度極高，支持海梨可能是桶柑變異而來的說法。 Through cluster analysis and principal component analysis of 16 vegetative characters, the tankan (Citrus tankan Hayata) accessions were divided into two main groups, big and small fruit group respectively. The accessions within each group displayed diversity as well; however, the grouping patterns were not relevant to the location we originally collected from. The result of the principal component analysis revealed that leaf length/leaf width, wing length, number of marginal serrations, oil glands on the margin/cm and oil glands /cm2 were the major discriminating characteristics. Besides, the first three principal components explained 76.28% of the observed variation. The dendrograms, generated by cluster analysis based on the 5 major discriminating traits and 16 vegetative characters, were similar to one another. Therefore, our result suggested that the 5 major discriminating traits could be useful for tankan genetic variance analysis and for early selection of fruit size. In the RAPD analysis, 265 primers with PCR products generated 6 bands per primer on average. 95% of the PCR product were reproducible and monomorphic. This result revealed high genetic similarity among the tankan accessions. The non-reproducibilty of the polymorphic bands (5%) implied that RAPD analysis were not applicable in the identification of the difference among tankan accessions. The 16 vegetative characters, cluster analysis and principle component analysis can also differenciate from tankan and haili(Citrus haili Tanaka). The high similarity of banding patterns of the RAPD analysis supported hypothesis that haili might derive from tankan.