DSpace collection: 研究計畫

解析阿拉伯芥HIT4調節染色質結構及活化靜默基因以促使植物耐熱之機制;Dissecting the Mechanisms of Arabidopsis HIT4-Mediated Decondensation of Chromocenter and Release of TGS in Protecting Plants against Heat Stress

title: 解析阿拉伯芥HIT4調節染色質結構及活化靜默基因以促使植物耐熱之機制;Dissecting the Mechanisms of Arabidopsis HIT4-Mediated Decondensation of Chromocenter and Release of TGS in Protecting Plants against Heat Stress abstract: 為瞭解植物耐受高溫逆境之機轉，進而以遺傳工程改良作物耐熱力以因應全球暖化之威脅，本實驗室以前向式遺傳學的策略，自ethyl methanesulfonate (EMS)處理過之阿拉伯芥M2子代中，篩選出一對高溫逆境失去耐受性之突變植株，命名為heat-intolerant 4 (hit4)。進一步的生理實驗發現，hit4雖失去先天性熱耐受能力(basal thermotolerance)，卻仍保有後天性熱耐受能力(acquired thermotolerance)。經基因定位、互補實驗及序列比對，確認hi;The Arabidopsis mutant heat-intolerant 4 (hit4) was isolated from an ethyl methanesulfonate-mutagenized M2 population on the basis of its inability to withstand prolonged heat stress (four days at 37°C). Further characterization indicated that hit4 was im;研究期間：10408~10507

環境逆境下水稻熱休克轉錄因子差異性調控機制分析;Analysis for the Mechanism of Differential Regulation of Rice Heat Shock Transcription Factors under Environmental Stress

title: 環境逆境下水稻熱休克轉錄因子差異性調控機制分析;Analysis for the Mechanism of Differential Regulation of Rice Heat Shock Transcription Factors under Environmental Stress abstract: 研究期間：10208~10307;Our previous studies have shown that the expression profiles of rice class I small heat shock protein (sHSP-CIs) genes were diversified in response to heat and azetidine (AZC) stresses. We have found that an AZRE (Azetidine responsive element; GTCCTGGACG), localized on the promoter regions of Oshsp17.3 and Oshsp18.0 genes, was associated with OshsfA4b and heat shock elements (HSEs) to regulate heat shock response and AZC-induced cytosolic protein response. However, OshsfA4b and AZRE did not involve in the induction of Oshsp16.9A gene under heat stress. In this three-year project, our major goal is to further study the differential regulatory mechanism for heat shock factors (HSFs) on the induction of sHSP-CIs genes. Firstly, using the expression level of Oshsp17.3::GUS as an indicator, we are trying to analyze the effects of AZRE and HSEs on the HSF-regulated expression of sHSP-CI genes. Secondly, we plan to screen and characterize other rice HSFs and Arabidopsis HSFs specific for AZC-induced expression of sHSP-CI genes. Thirdly, we plan to introduce AZRE and HSE into rice genome and establish transgenic rice plants, which are used to study the differential regulation of HSFs. Fourthly, we try to use EMSA (Electrophoretic Mobility Shift Assay) technique to analyze the interaction between specific HSFs and AZRE and HSE. Finally, we plan to compare tunicamycin-induced UPR (unfolded protein response) with AZC-induced CPR and UPR.

解析阿拉伯芥HIT4調節染色質結構及活化靜默基因以促使植物耐熱之機制;Dissecting the Mechanisms of Arabidopsis HIT4-Mediated Decondensation of Chromocenter and Release of Tgs in Protecting Plants against Heat Stress

title: 解析阿拉伯芥HIT4調節染色質結構及活化靜默基因以促使植物耐熱之機制;Dissecting the Mechanisms of Arabidopsis HIT4-Mediated Decondensation of Chromocenter and Release of Tgs in Protecting Plants against Heat Stress abstract: 研究期間：10208~10307

解析囊泡繫鏈因子HIT1對細胞膜熱穩定性之影響及其作用機轉;Dissecting the Mechanism Underlying Arabidopsis HIT1-Mediated Plasma Membrane Thermoadaptation

title: 解析囊泡繫鏈因子HIT1對細胞膜熱穩定性之影響及其作用機轉;Dissecting the Mechanism Underlying Arabidopsis HIT1-Mediated Plasma Membrane Thermoadaptation abstract: 研究期間：10108~10207;The plasma membrane plays many vital roles in plant cells, from forming a selective barrier so that a cell can be defined, to providing a suitable environment in which integral proteins can function. Meanwhile, the plant plasma membrane is a direct and major target of heat stress. Maintenance of the integrity of the plasma membrane under heat-stress conditions depends on prompt repair and/or remodeling of the membrane, both of which necessitate the effective transport of membrane components to and from the plasma membrane via directed intracellular trafficking of vesicles. Accumulating evidence has suggested that vesicle tethering, which is mediated by tethering factors, is central to efficient and accurate vesicular trafficking. However, no experimental data have clarified the protective role of tethering factors on the thermostability of the plasma membrane and its effects on heat tolerance in plants. Using a forward genetic approach, we have isolated an EMS-induced hit1-1 (heat-intolerant 1) mutant of Arabidopsis, whose growth is more sensitive to inhibition by high temperature than that of the wild-type. The mutated gene was later identified to encode a subunit of the vesicle tethering complex. Under heat-stress conditions, the plasma membrane of hit1-1 was less stable than that of the wild-type, as determined by an electrolyte leakage assay. Furthermore, hit1-1 was sensitive to the duration (sustained high-temperature stress at 37°C for 3 days) but not the intensity (heat shock at 44°C for 30 min) of exposure to heat, which suggested that HIT1 is involved more in the remodeling than in the repair of plasma membrane. Collectively, HIT1 is the first and so far the only tethering factor linked to thermoadaptation of the plasma membrane. Nevertheless, many fundamental and important questions are still waiting to be answered. For example, is HIT1 responsible for editing plasma membrane by changing lipid composition under heat stress condition? Will this editing alter fatty acid saturation level? Will this alteration affect the fluidity of plasma membrane? Will this affection correlate the thermolabile property observed in hit1-1 plasma membrane? In addition, dose HIT1-mediated vesicle trafficking also influence thermostabillity of other endomembranes such as those of ER, Golgi and vacuole? To answer these critical questions, experiments include fatty acid profiling by gas chromatography, membrane fluidity assay by fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH), biogenic membrane thermostability examination by heat-induced chlorophyll fluorescence (changes of Fo in slow heating), and endomembrane thermostability analysis by testing transgenic plants expressing fluorescent proteins (FP) fused with well-established ER, Golgi and tonoplast membrane targeting sequences, will be conducted using both WT and hit1-1 plants grown in either optimal or high temperatures. These results will definitely provide significant information for better elucidating the causal linkage between vesicle trafficking and heat tolerance in plants. In the meantime, characterization of a newly isolated hit4 mutant will be continued.