應用粒線體DNA及核醣體區段探討台灣地區豆花薊馬(Megalurothrips usitatus (Bagnall))之遺傳變異

豆花薊馬(Megalurothrips usitatus (Bagnall))是豆科植物上甚為普遍之害蟲，依賴形態特徵幾乎無法鑑定此薊馬的不同地理族群。本研究以台灣16個地區之豆花薊馬，利用母系遺傳特性的COI mtDNA及雙系遺傳特性的ITS2 rDNA區段建立分子特徵，並分析其遺傳變異，探討其族群間的基因交流及雜交的可能性。此外，針對薊馬DNA的純化條件，比較3種DNA萃取試劑，獲得蟲體不需戳洞，只需15分鐘即有很好效果的萃取方法。在COI mtDNA定序成功的177條序列中，存有 20組獨特的基因型，基因型歧異度為0.65851，核酸歧異度是0.00233，各族群序列變異為0.1%~0.4%，分化指數FST值為0.00290~0.15927，基因交流指數Nm值為2.64 ~172.00。ITS2 rDNA區段定序成功共計170條序列，存有 143組獨特的基因型，基因型歧異度為0.9954，核酸歧異度是0.01751，各族群序列變異為0.4%~1.2%，FST值為0.00727~0.28264，Nm值為0.63~34.13。以Neighbor-Joining的類聚方法探討親緣關係，COI mtDNA被分為2個支系(I 和II)及ITS2 rDNA區段分為7個支系(A~G)，兩個基因的演化關係多不一致。由ITS2 rDNA區段的異質性組成探討發現，單一個體內的ITS2區段會有很多個，當序列出現GAP時，會導致後續序列發生重疊不易判讀之現象。綜合ITS2 rDNA區段及COI mtDNA在不同分群層次的序列變異分析、族群遺傳變異分析、異質性組成分析及親緣關係樹分析顯示，母系遺傳的COI變異與雙系遺傳的ITS2變異有不一致的分化情形，雖難釐清自然擴散或人為因素，但說明了台灣各地豆花薊馬族群間的雜交頻度頗高的特性。

關鍵字

豆花薊馬； COI mtDNA ； ITS2 rDNA ；基因選殖；遺傳變異

並列摘要

Megalurothrips usitatus (Bagnall) is a very general pest on the legume. Different geographical populations can not be identified by morphological characteristics. This study utilizes COI mtDNA and ITS2 rDNA region of M. usitatus from different areas in Taiwan to analyze its genetic variation, and address gene flow among different populations. In addition, three kinds of DNA extraction methods were tested and high quality of DNA could be acquired within 15 minutes in the undestroied condition of thrips specimens. In 177 COI sequences, 20 unique haplotypes were found, and the estimate of haplotype diversity, nucleotide diversity, sequence variations among populations, differentiated FST, and gene flow Nm value were 0.65851, 0.00233, 0.1~0.4%, 0.00290~0.15927, and 2.64~172.00, respectively. In 170 ITS2 sequences, 143 haplotypes were found. The haplotype diversity, nucleotide diversity, sequence variations among populations, differentiated FST, and gene flow Nm value were 0.9954, 0.01751, 0.4%~1.2%, 0.00727~0.28264, and 0.63~34.13, respectively. Result of phylogenetic analysis, based on Neighbor-Joining method, showed there are 2 lineages in COI sequences, and 7 lineages in ITS2 sequences. With individual heterogeneity analysis of ITS2 rDNA region, we found that overlapping nucleotides will interfere the sequence resolution as gap was existed. To combine the above evidences of ITS2 rDNA region and COI mtDNA sequences, that differentiated processes of mtCOI is inconsistent to that of nuclear ITS2 rDNA region. The results also proved that high frequency possibilite of hybridization occurred in different population of M. usitatus either from natural colonization or artificial dispersal of this thrips.

並列關鍵字

Megalurothrips usitatus (Bagnall) ； COI mtDNA ； ITS2 rDNA region ； heterogeneous ； genetic structure

參考文獻

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19.Avise, J. C. 1994. Molecular Markers, Natural History and Evolution. Chapman and Hall, Inc. New York. 684pp.

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應用粒線體DNA及核醣體區段探討台灣地區豆花薊馬(Megalurothrips usitatus (Bagnall))之遺傳變異

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