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標題: | 染色質重塑複體 SWR1 組件 ARP6 對於阿拉伯芥熱休克反應及耐熱性之研究 Studies on the Role of Arabidopsis ARP6, a Component of the Chromatin Remodeling SWR1 Complex, in Heat Stress Response and Thermotolerance |
作者: | Wei-Di Wang 王暐迪 |
指導教授: | 常怡雍(Yee-Yung Charng) |
關鍵字: | 長時間中等高溫逆境,熱休克反應,熱耐受性,半乳糖基甘油二酯,雙半乳糖基甘油二酯,葉綠體, prolonged moderate heat stress,heat shock response,thermotolerance,MGDG,DGDG,chloroplast, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 熱逆境所影響的層面相當複雜,其中包括了發育、代謝、蛋白質穩定度、細胞膜流動性以及基因調控。這些高溫所造成的傷害將會造成農作物產量的銳減。於是瞭解植物在熱逆境下的反應以及耐受機制就變得相當重要。目前已知某些具有基因調控功能的染色質修飾蛋白質也負責偵測週遭溫度變化。然而,它們在熱逆境下的反應以及耐受機制中的角色並不為人所知。因此,我們測試了幾個相關的阿拉伯芥突變株在不同高溫條件下的耐受性。結果顯示,44 oC極端高溫處理對於 ARP6 的兩個突變株 arp6-1 以及 suf3 的影響與野生株的情形差異不大。但是,該突變株一致地對長時間暴露於中等高溫 (35 oC,6天) 的耐受性 (TMHT) 有明顯的缺失。ARP6 所產生的蛋白質為染色質重塑複體 SWR1 的一部份。該複體之功能是送入組蛋白 H2A.Z 取代 H2A,進而調控了熱休克蛋白HSP70 和開花調控因子FLC 的基因表現。利用西方墨點法偵測多種熱休克蛋白,如 HSP101、90、70 和 HSA32,發現突變株與野生型之間並沒有明顯的差異。然而,在突變株中,半乳糖脂類,如半乳糖基甘油二酯 (MGDG) 和雙半乳糖基甘油二酯 (DGDG) 的含量卻受到了顯著的影響。在 TMHT 條件下,發現半乳糖脂類含量及其相關合成基因表現,在突變株中的數值皆一致地低於野生型。此外,突變株中的光系統 II (PSII) 活性也比野生型下降得更快。以上這些結果暗示,ARP6 參與調控半乳糖脂類合成基因的表現,進而調整該脂類在葉綠體內含量,使得阿拉伯芥對中等高溫的長時間逆境產生耐受性。 Heat stress (HS) has a complex effect on many aspects of plant life, such as development, metabolism, protein stability, membrane fluidity, and gene regulation. These HS effects can result in a drastic reduction in agronomic yield. Thus, understanding how plants respond to and tolerate HS is very important. Chromatin modification components are known to involve in ambient temperature sensing. However, their roles in HS tolerance are not clear. To identify chromatin modification components required for HS tolerance, we had assessed the thermotolerance levels of several related mutants under different HS regimes. Among the heat sensitive mutants we identified arp6-1 and suf3, T-DNA insertion and deletion mutant of ARP6 respectively, specifically showed severe defect in thermotolerance against moderate high temperature (TMHT, at 35 oC for 6 days), but not under acute HS associated with exposure at 44 oC. ARP6 encodes a subunit of the SWR1 complex that deposits the histone H2A.Z into the nucleosomes at loci such as FLC, a flowering regulator, and HSP70. Western blot analyses showed that the levels of heat shock proteins (HSPs) including HSP101, 90, 70 and HSA32 did not show significant difference between the wild type (WT) and suf3. However, the levels of galactolipids, such as monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), in the mutants were altered. Under TMHT condition, the galactolipids contents and expression of the synthesis related genes in arp6 mutants were substantially lower than that of the WT. Moreover, photosystem II (PSII) activity in the mutants decreased faster than that of WT under TMHT condition. These data suggest that ARP6 is involved in sustaining the synthesis of MGDG and DGDG in chloroplast by modulating the expression of galactolipids synthesis genes, which confers tolerance of PSII against prolonged moderate HS. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/35307 |
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顯示於系所單位: | 生化科技學系 |
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