本文選題：冰凍脅迫 + 差熱分析��； 參考：《魯東大學》2017年碩士論文

【摘要】：低溫條件下植物的結冰模式,即胞外或胞內(nèi)結冰直接決定著細胞的生死,目前胞外結冰相關的直接證據(jù)還很少,特別是缺乏熱力學的證據(jù)。本研究用高分辨率差熱掃描和顯微觀察分析了女貞(Ligustrum lucidum)和冬青衛(wèi)矛(Euonymus japonicus)葉片在降溫過程中的結冰放熱行為,發(fā)現(xiàn)了兩種植物胞外結冰的熱力學和組織結構變化的新證據(jù)。兩種植物的活葉片在冷卻過程中均呈現(xiàn)雙放熱峰,即雙相結冰的特征,而預先冰凍殺死的葉片和葉片組織提取液浸潤的濾紙片在同樣的冷卻過程中僅有一個快速的大的單放熱峰,即單相結冰的特征。從開始結冰放熱到到達放熱峰頂點所需要的時間,女貞的新鮮離體活葉片為186秒,冰凍殺死葉片僅為11秒;對于冬青衛(wèi)矛來說,從開始結冰放熱到到達放熱峰頂點所需要的時間,新鮮離體活葉片為141秒,冰凍殺死葉片僅為14秒。根據(jù)結冰放熱量積分得到的體內(nèi)總水分結冰一半的結冰弛豫時間,女貞的新鮮離體活葉片的結冰弛豫時間為189秒,女貞冰凍殺死葉片的結冰弛豫時間為73秒;冬青衛(wèi)矛的新鮮離體活葉片的結冰弛豫時間為179秒,冰凍殺死葉片的結冰弛豫時間為87秒。女貞新鮮離體活葉片的過冷度為5.11℃,冰凍殺死葉片過冷度為5.72℃。冬青衛(wèi)矛新鮮離體活葉片的過冷度為7.58℃;冰凍殺死葉片過冷度為7.36℃。這些結果顯示兩種植物的活葉片和冰凍殺死的葉片的過冷度沒有明顯的差別。實驗從熱力學上提供了兩種高等植物葉片在低溫條件下細胞外首先結冰的證據(jù),并顯示了兩種植物的活葉片和冰凍殺死葉片在冷卻過程中的相應結冰模式和過冷度的差別。目前尚未看到國際上有細胞外首先結冰的熱力學證據(jù)和死活葉片結冰模式的熱力學差別,因此實驗結果為進一步深入了解植物的冰凍傷害機制提供了新的途徑。顯微觀察也顯示了結冰過程中,在細胞間隙中形成無色的大量冰晶和脫水收縮但細胞內(nèi)容物未流失的染色細胞,顯示出胞外結冰的特征。雖然差熱分析在植物抗凍性的研究中已有了大量的報道,但目前尚未看到國際上有關于以高分辨率差熱分析揭示細胞外結冰的熱力學證據(jù)。實驗結果為進一步深入了解植物的冰凍傷害機制提供了新的證據(jù)和研究方法。不同植物在溫度下其光合作用和呼吸作用強度表現(xiàn)出明顯差別。植物莖呈現(xiàn)出復雜的的結冰模式,其機理有待進一步研究。月季和冬青衛(wèi)矛在不同梯度的低溫環(huán)境下測得的電解質(zhì)外滲率實驗顯示出冬青衛(wèi)矛的半致死溫度明顯低于月季的半致死溫度,表現(xiàn)出更強的抗凍性。
[Abstract]:The freezing pattern of plants under low temperature, that is, extracellular or intracellular ice, directly determines the cell life and death. At present, there are few direct evidences related to extracellular ice, especially the evidence of thermodynamics.In this study, the freezing and exothermic behavior of leaves of Ligustrum lucidum and Euonymus japonicus during cooling was studied by high resolution differential thermal scanning and microscopic observation. New evidences of thermodynamics and tissue structure changes of extracellular ice in two plants were found.The living leaves of the two plants show double exothermic peaks during cooling, that is, the characteristics of biphasic ice formation.In the same cooling process, there is only one fast and large single exothermic peak, that is, single phase ice formation, in the pre-freezing of the leaf and the filter paper infiltrated by the tissue extract of the leaf.Between the beginning of ice and heat and the time required to reach the top of the exothermic peak, the freshly detached leaves of the privet were 186.00 seconds, and the freeze-killed leaves were only 11 seconds; for the holly spear,From the beginning of freezing and heat release to the peak of exothermic heat, the fresh live leaves are 141 seconds, and the frozen leaves are only 14 seconds.According to the calorific integral of ice release, the ice relaxation time of the fresh living leaves of Ligustrum privet is 1890 seconds, and that of the leaves killed by freezing is 73 seconds.The freezing relaxation time of fresh leaves was 179 seconds, and that of frozen leaves was 87 seconds.The supercooling degree of fresh living leaves of Ligustrum privet was 5.11 鈩，

本文編號：1748997