台灣油茶種原葉部性狀及ISSR DNA歧異度之研究

Abstract

本研究以蒐集自台灣三個地區之33個大果油茶收集系及五個地區之46個小果油茶收集系為材料，共以79個油茶收集系進行葉部性狀變異及遺傳歧異度之研究。葉部性狀的調查研究結果顯示，經由葉長、葉寬、長寬比、葉厚、鋸齒數、內折度及反轉度等七個數量性狀的主成分向量分析，可清楚的將大果油茶及小果油茶分群；以多變數判別分析方法所建立之大果油茶和小果油茶判別公式，亦具有極高的判別度，顯示葉部性狀可應用於鑑別大果油茶與小果油茶。葉長、葉寬、葉厚、長寬比及鋸齒數等五個性狀為穩定性較佳的數量性狀，其平均變異係數 (CV)皆在10 %左右，未來建立品種性狀檢定表應可考慮將此五個性狀納入調查項目，作為品種間鑑別的參考依據。 遺傳歧異度研究利用ISSR分子標誌為工具，以及茶樹栽培品種武夷做為外源對照，本研究共篩選得到11條ISSR引子，獲得31個訊號較強且具有明顯再現性的多型性條帶。ISSR分子標誌之群聚分析與主成份向量分析結果相似，全體種原間平均遺傳相似性為52.8 %。若將大果油茶與小果油茶作區分，小果油茶46收集系間平均遺傳相似性為54.8 %，大果油茶33收集系間平均遺傳相似性為58.9 %。AMOVA分析結果顯示大果油茶與小果油茶種內變方大於種間變方，更近一步劃分地區進行分析，結果顯示大果油茶和小果油茶地區間變方成分皆顯著 (26.42 %及34.71 %)，但區域內的變方大於區域間變方，顯示出大果油茶和小果油茶種內均具有高遺傳歧異度，且遺傳變異主要來自於同一區域內個體間。POPGENE分析族群遺傳變異結果顯示，大果油茶及小果油茶皆具有比一般蟲媒花略高的族群遺傳分化係數 (Gst)，且基因流轉值 (Nm) 皆小於1，顯示出同一物種內區域族群間分化的現象。

Genetic variation of leaf characters and ISSR DNA markers for 33 Camellia oleifera accessions (collected from 3 areas) and 46 Camellia tenuifolia accessions (collected from 5 different areas) in Taiwan was studied. Based on seven leaf traits, including leaf length, leaf width, leaf thickness, leaf ratio, numbers of serrations, percentage of difference between actual length of leaf and the natural ones and percentage of difference between actual width of leaf and the natural ones, principle component analysis result could divide C. oleifera and C. tenuifolia apart clearly. Formula established by multivariate discriminate analysis is very powerful and reliable to distinguish the oiltea Camellia species. Coefficients of variation (CV) of leaf length, leaf width, leaf thickness, leaf ratio and numbers of serrations are around 10 %, suggesting the satisfactory stability of the traits. These traits could be catalogued and used for variety identification. Molecular level variation was revealed by 11 ISSR primers which could stably generate 31 robust polymorphic bands. Similar results were found in cluster analysis and principle component analysis based on ISSR markers. The ISSR DNA marker similarities within species are 54.8 % in C. tenuifolia and 58.9 % in C. oleifera. The result of AMOVA shows that the variation component within species is larger than between species and both regional variation components of C. oleifera and C. tenuifolia are statistically significant (26.42 % and 37.41 %). The variation within regions is larger than among regions indicating that high genetic variation is existed in C. oleifera and C. tenuifolia populations. POPGENE analysis result shows both C. oleifera and C. tenuifolia have the higher Nei's coefficients of gene variation (Gst) values than common insect pollination plants. The estimates of gene flow from both Gst values were below 1, implying the existence of differentiation among different populations of a species.