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標題: 建立大量表現高鹽太古生物甜菜鹼生合成基因之耐鹽植物轉殖系
Establishment of Salt-Tolerant Transgenic Plants by Expressing Genes for Glycine Betaine Biosynthesis from Halophilic Methanoarchaea M. Portucalensis
作者: 顏宏真
關鍵字: 生物技術;商品化;compatible solutes;glycine betaine;Halophilic methanoarchaea;plant stress;salt tolerance
甜菜鹼(glycine betaine)是一個保護係數最高的相容質,可大量累積在特定的耐鹽植物中,但是在不耐鹽的阿拉伯芥及水稻中則不會累積。高等植物甜菜鹼生合成過程是經由choline 進行氧化而得,而甜菜鹼在體內的累積量常受限於choline 的取得。嗜鹽甲烷太古生物Methanohalophilus portucalensis strain FDF1會使用另一個途徑合成甜菜鹼,經由胺基酸glycine 進行三次甲基化而得,所參與生合成步驟共有兩個酵素GSMT (glycine sarcosine N-methyltransferase)及SDMT (sarcosine N, N-dimethylglycine N-methyltransferase)。本計畫擬將此二酵素基因轉殖入不累積甜菜鹼的阿拉伯芥及水稻,篩選甜菜鹼累積量高的轉植株,進行滲透逆境(高鹽、缺水及低溫)處理後,測定種子萌芽率、相對水分含量、根長、及光合作用速率等生理參數,並與甜菜鹼的累積量進行相關性分析,以評估此嶄新之代謝途徑所提供之相容質,對於不耐鹽植物的耐鹽性提升之潛力。本計畫將分三個主題進行,預計在三個年度內完成。第一主題:MpGSMT 與MpSDMT 酵素特性分析。第二主題:大量表現 MpGSMT 與MpSDMT 之阿拉伯芥轉殖系耐鹽生理特性分析。第三主題:大量表現MpGSMT 與MpSDMT 之水稻轉殖系耐鹽生理特性分析。

Glycine betaine (GB) is a compatible solute that has the highest osmo-protectivepotential. It accumulates to a high level in some halophytic species, but does notsynthesize in most glycophytes, such as Arabidopsis and rice. The biosyntheticpathway for GB in higher plants is derived from the oxidation of choline. However,choline is not a high-accumulating metabolite which limits the ability to produceglycine betaine in most plants. Halophilic methanoarchaea Methanohalophilusportucalensis strain FDF1 is able to synthesize GB from a three-step methylation ofglycine. Enzymes involved in catalyzing this reaction are GSMT (glycine sarcosineN-methyltransferase) and SDMT (sarcosine N, N-dimethylglycineN-methyltransferase). In this proposal, we will introduce these two genes intoArabidopsis and rice via Agrobacterium-mediated transformation and screen forhigh-GB accumulating transgenics. Several physiological parameters includingseed germination rate, root growth and bending assay, relative water content, andPSII activity will be used to access the viability of transgenic plants under osmoticstresses. This will provide valuable information of the correlation between GBaccumulation and stress tolerance in these two model plants.There are three main topics in this three-year proposal:Topic 1. Characterization of enzymatic properties of MpGSMT and MpSDMTTopic 2. Functional analyses of transgenic Arabidopsis overexpressing MpGSMTand MpSDMTTopic 3. Functional analyses of transgenic rice overexpressing MpGSMT andMpSDMT
其他識別: NSC100-2321-B005-005-MY3
Appears in Collections:生命科學系所

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