以4-coumarate CoA ligase基因進行台灣冷杉族群親緣地理關係研究

Phylogeography of Abies kawakamii (Hayata) Ito based on 4-coumarate CoA ligase gene.

洪茂森(Mao-Sen Hung)

指導教授 ： 何國傑

共同指導教授 ： 林讚標

國立臺灣大學/生命科學院/植物科學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.02507

摘要

本研究以核內基因4- coumarate CoA: ligase (4CL)的序列片段 (約1174 bp)，分析台灣冷杉 (Abies kawakamii (Hayata) Ito)的族群結構及親緣地理關係。台灣冷杉樣本採自八個族群，分別位於大霸尖山 (8株)、雪山 (8株)、合歡山 (9株)、奇萊山 (8株)、北二段 (6株)、玉山 (8株)、關山 (8株)以及南湖大山 (8株)，以每個單株的基因體為模板進行PCR反應後，再將產物進行選殖，每個單株取兩個選殖株進行定序，共分析了135個序列。對這些序列分析發現可分為兩群，顯示其中可能包含兩個獨立基因，命名為4CL1及4CL2。我們選取其中4CL1基因共88個序列做後續研究，序列中包含五個exon，四個intron。Intron總長度約為380 bp，其中包含65個多型性位點，其中60個來自點突變 (point mutation)，5個來自插入或刪除 (indel)，共有71個基因型，大部分混合分布於各族群當中。若以個別的intron進行分析，則可發現四個intron所獲得基因樹呈現一致的規律。大多數的序列歸屬於原始型及衍生型兩種基因型，其餘則為末端型。各族群的基因型除只有原始型、衍生型外，均為非常unique的末端型為主。這些族群正往高海拔退縮，同時歷經瓶頸效應與基因漂變力量的作用，導致混合的基因型而很可能是避難族群的特色。而根據族群間FST/KST與Dxy所得數值做平均分別找到雪山、玉山與雪山、北二段、奇萊為最高值，為分化最強的區域，可能是主要的避難族群所在。
根據4CL1 DNA序列或是種子形態，Abies homolepis或Abies mariesii可能皆非台灣冷杉的祖先。
我們針對4CL1基因座數目進行研究，發現台灣冷杉種子內的配子體(haploid)中至少包含16個以上的4CL基因座。我們選用的基因4CL1可能有6個以上的基因座，而且序列非常相似且序列間只有singleton的差異。

關鍵字

台灣冷杉 ； 親緣地理

並列摘要

Population genetic structure and phylogeographical relationships of Abies kawakamii (Hayata) Ito in Taiwan were studied by analyzing the DNA sequence of 4- coumarate CoA: ligase (4CL, 1174 bp). Samples were collected from eight alpine populations: Kuanshan, Yushan, Chilaishan, Hohuanshan, Nanhutashan, Tapachienshan, Tahsuenshan, and Wumingshan. Two clones of 4CL gene from each individual were sequenced. From a total of 135 DNA sequences of 68 individuals, 4CL can be separated into two gene family: 4CL1 and 4CL2. One of the gene, 4CL1 containing 88 sequences was further studied. The DNA fragment of 4CL1 consisted of five exons and four introns. The total length of intron was 380 bp, and contained 65 polymorphic sites: 60 point mutations and five insertions, giving a total of 71 haplotypes. The genealogical trees generated from these four introns showed similar pattern. Most of the sequences of each intron belonged to ancestral haplotype and derived haplotype, and many unique terminal haplotypes. Populations shared ancestral haplotype, derived haplotype, and the unique terminal haplotypes. These populations were retreating to higher altitude, experiencing an effect of bottleneck and genetic drift resulting in the composition of haplotype mentioned above that could characterize the refuge populations. Based on the average values of parameters of population differentiation, FST and KST, and population divergence DXY, we found that Tahsuenshan, Yushan, Wumingshan, and Chilaishan had the highest values indicating the possible major region of refugia for Abies kawakamii.

According to 4CL1 DNA sequence and the morphology of seed, neither A. homolepis nor A. mariesii of Japan is ancestral to A. kawakamii. In terms of number of loci of 4CL1 gene, we found six loci among 16 in the gametophyte. These 4CL1 DNA sequences were very similar and only exhibited single nucleotide polymorphism.

並列關鍵字

phylogeography ； Abies kawakamii

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