太平洋地區蔥薊馬(Thrips tabaci Lindeman)之 遺傳變異

Genetic variation of Thrips tabaci Lindeman

曾麗月(Li-Yueh Tseng)

指導教授 ： 張念台

國立屏東科技大學/農學院/植物保護系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00249

摘要

蔥薊馬(Thrips tabaci Lindeman)在歐洲、亞洲及太平洋群島、美洲、非洲東部及澳洲均有其分佈。其體色有淺色型及深色型，屬多態型昆蟲，且體型微小，世代短變異速率較快。以往依據幼蟲形態及體色，不但鑑定不易亦無法區別相互間的遺傳變異。本實驗收集太平洋地區蔥薊馬，並利用核醣體ITS2 ( internal transcribed spacer 2)及粒線體細胞色素氧化酶次單位元一 (cytochrome oxidase subunit I, COI)，進行遺傳變異分析。收集測試標本依國家可區分為13個族群，台灣 (Taiwan)地區與國外地區，總數共為49個亞族群，成功複製出86條序列。蔥薊馬的ITS2 rDNA區段種內差異為0.4~3.0% , COI mtDNA區段種內差異為0~3.1%。在地區性序列差異方面，若將僅有一個族群的中國 (China)、夏威夷 (Hawaii)、秘魯 (Peru)及荷蘭 (Netherlands)4地區相比ITS2 rDNA區段，以中國地區序列差異較高為0.7~0.9%，COI mtDNA區段則較無顯著性差異。另一方面，ITS2 rDNA 區段基因型歧異度 (haplotype diversity)最高為秘魯和中國的1.00000，其次為美國 (America) 0.87273，紐西蘭 (New Zealand) 0.83333及澳洲 (Australia) 0.80300，COI mtDNA區段haplotype diversity最高則為荷蘭1.00000，其次為紐西蘭0.83333。ITS2 rDNA區段遺傳分化指數 (FST) 以台灣與墨西哥 (Mexico)最高達0.60630，COI mtDNA區段夏威夷與澳洲、台灣與美國及台灣與澳洲遺傳分化指數 (FST)最高分別達0.64935、0.64739及0.60240，表示該地區族群間之基因交流頻繁，而歧異度較低。以PCR產物直接定序其ITS2 rDNA區段於170的位置，序列顯現雜亂訊號，故進一步利用大腸桿菌選殖法分析序列組成，經異質性組成探討，以日本地區基因歧異度 (haplotype diversity)最高達0.9684，共有17個獨特基因型 (haplotype)。由以上分析結果顯示，蔥薊馬遺傳變異，在太平洋地區的不同國家有差異，若引進近親種的外來生物或不同族群，會使雜交機率提高，進而改變原有族群之基因組成，形成雜交優勢。

關鍵字

蔥薊馬 ； 太平洋地區 ； 核醣體DNA ITS2區段 ； 粒線體細胞色素氧化酶次單位元一 ； 遺傳變異

並列摘要

Onion thrips (Thrips tabaci Lindeman), the cosmopolitan pest, has distributed around Europe, Asia, pacific islands, America, east of Africa and Australia. Because of the tiny body size, short life cycle, and polymorphology with body color from light to dark, it is not only hard to be identified but also impossible to be distinguished their genetic variation among populations. In this study, both genes of nuclear internal transcribed spacer 2 (ITS2) region and mitochondrial cytochrome oxidase subunit I (COI) of onion thrips collected from Pacific Rim were used to detect and analyse their intraspecific genetic diversity. There are 86 sequences successfully to be detected in those onion thrips populations from 13 countries of Pacific Rim with 49 sub-populations. The sequences variation of ITS2 rDNA and COI mtDNA region were 0.4~3.0% and 0~3.1%, respectively. The comparison of sequences in 4 single sample areas, i.e. China, Hawaii, Peru, and Netherlands, showed that the largest variation of ITS2 rDNA region (0.7~0.9%) was found in China populations. The absolute haplotype diversity of ITS2 rDNA region were found in T. tabaci samples of Peru and China (1.00000) and following with America (0.87273), New Zealand (0.83333) and Australia (0.80300). The highest haplotype diversity of COI mtDNA region were found in samples of Netherlands (1.00000) and following with New Zealand (0.83333). The higher fixation index (FST) of ITS2 rDNA region were found between the thrips populations of Taiwan and Mexico (0.60630), and the higher FST of COI mtDNA region were Hawaii and Australia (0.64935), Taiwan and America (0.64739), Taiwan and Australia (0.60240). These indicated that higher frequencies in gene flow, and thus lower genetic diversity, occurring between those two populations. Cloning method was used to study the ITS2 rDNA region composition as the direct sequending of PCR products shown the overlapping at nucleotides positions of 170. The highest haplotype diversity of ITS2 rDNA region was found in populations of Japan (0.9684) with 17 haplotypes totally, in comparing the heterogeneous composition of all specimens. The genetic analyses of both genes indicated that different genetic variations occurring in different populations of T. tabaci from Pacific Rim. Thus, the unexpected introduction of foreign populations of this pest should be avoid to reduce the hybridization adaptation.

並列關鍵字

Thrips tabaci ； Pacific Rim ； Internal transcribed spacer 2 ； mitochondrial cytochrome oxidase subunit I ； Intra-specific variation

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