台灣產黃芩屬植物花青素生合成途徑之CHS、DFR及UFGT基因的適應性演化

台灣產黃芩歷經多次起源，經近期快速種化而形成高度特有種比例。在外觀上，台灣產黃芩除了物種間有固定差異的花色外,種內大多數個體間也可觀察到葉背呈現粉紫紅色的情形，而這些色彩的轉變可能與花青素的表現及多樣性有關,更影響他們的生殖、生理及環境適應。為得知其台灣產黃芩是否受到不同環境因子的影響而導致變異的適應性演化，我們擬檢測台灣產黃芩花色變異的演化壓力，將利用花青素生合成途徑(anthocyanin biosynthetic pathway)的上游(chalcone synthase ,CHS)、中游(dihydroflavonol 4-reductase ,DFR)、下游(flavonoid 3-O-glucosyltransferase ,UFGT)等關鍵基因作為研究對象，探討這些基因在不同的物種間是否承受不同的天擇壓力。本研究自野外收集台灣產七種黃芩，萃取DNA，後對上述基因進行定序，定序結果進行比對確認及序列整理後,以基因序列的同義置換率及非同義置換率作為估算適應性演化的準則，初探台灣產黃芩CHS 、DFR、UFGT 基因演化是否受天擇壓力影響，並檢測是否有特定支系或特定密碼子遭受天擇壓力。本實驗結果提供黃芩的花青素生合成途徑相關基因天擇的證據，並解釋植物色彩在生合成調控途徑中如何造成物種的適應及多樣性。

關鍵字

黃芩；花青素生合成途徑；適應性演化；天擇； CHS ； DFR ； UFGT

並列摘要

Taiwanese skullcaps (Scutellaria, Lamiaceae) were sourced from several times of different origins and rapidly evolved since colonized becoming the high proportion of endemic species. In observed of external, Taiwanese skullcaps were not just has the variation of florescence colors between species but also can find some purple color on leaf back between individual, those color variation depended by anthocyanin performance and diversity, and influence ther reproductive、 physiology and adaptation of environment. These rapidly spectated species are diversified in their florescence colors which are known to be related to reproduction, physiology, adaptation and genetic diversity. To find out the adaptive evolution signatures of the color diversity in Taiwanese skullcaps, I focus on the anthocyanin biosynthetic pathway and choose upstream gene (chalcone synthase ,CHS)、midstream gene (dihydroflavonol 4-reductase ,DFR) and downstream gene (flavonoid 3-O-glucosyltransferase ,UFGT) to be my target gene, to investigate the selection pressure of those genes. In this research, I extracted the genomic DNA from seven Taiwanese skullcaps, and confirming the accuracy after DNA sequencing, For detecting the positively selective pressure on specific lineages and specific codons of Taiwanese skullcaps, the ratio of nonsynonymous substitution rate and synonymous substitution rate will be calculated under different evolutionary model. Consequently, I will try to resolve the relationship between the evolution of CHS、DFR、UFGT in skullcaps, to explain the possibility of the adaptation and diversity in biosynthetic pathway with plant color.

並列關鍵字

Scutellaria ； anthocyanin biosynthetic pathway ； adaptive evolution ； natural selection ； CHS ； DFR ； UFGT

參考文獻

Hsieh T-H, Huang T-C. 1995. Notes on the Flora of Taiwan (20)-Scutellaria (Lamiaceae) in Taiwan. Taiwania 40:35-56.

Aguilar A, Roemer G, Debenham S, Binns M, Garcelon D, Wayne RK. 2004. High MHC diversity maintained by balancing selection in an otherwise genetically monomorphic mammal. Proceedings of the National Academy of Sciences 101:3490-3494.

Atchley WR, Zhao J, Fernandes AD, Druke T. 2005. Solving the protein sequence metric problem. Proceedings of the National Academy of Sciences of the United States of America 102:6395-6400.

Chalker-Scott L. 1999. Environmental significance of anthocyanins in plant stress responses. Photochemistry and Photobiology 70:1-9.

Chen J-C, Jiang C-Z, Gookin T, Hunter D, Clark D, Reid M. 2004. Chalcone synthase as a reporter in virus-induced gene silencing studies of flower senescence. Plant molecular biology 55:521-530.

國際替代計量

台灣產黃芩屬植物花青素生合成途徑之CHS、DFR及UFGT基因的適應性演化

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