【作者】 张宁宁；

【导师】 黄进勇；

【作者基本信息】 郑州大学 ， 生态学， 2012， 硕士

【摘要】 本课题旨在是研究和探索白芥幼苗在干旱胁迫下的生理生化响应和柠檬酸合酶机制。实验采用土培法结合PEG6000模拟干旱胁迫,在白芥幼苗期对白芥进行干旱处理。处理浓度设有10%、15%、20%三个梯度及对照CK,处理时间采取梯度设计,分别为3天、6天、9天和12天,处理结束进行取样。实验材料选用抗旱型白芥品种。通过测定白芥叶片叶绿素含量、可溶性糖含量、可溶性蛋白含量、丙二醛含量、SOD酶活性、CAT酶活性和POD酶活性等研究和揭示白芥幼苗干旱胁迫下的生理生化响应；通过对15%和20%PEG处理的白芥幼苗叶片在三种处理时间下柠檬酸合酶的的荧光定量PCR结果探讨和研究白芥幼苗在干旱胁迫下的柠檬酸合酶表达机制。研究结果表明,对白芥幼苗进行不同浓度和不同时间的干旱胁迫处理后发现,干旱胁迫幼苗形态与对照有较大差别。茎部变细变弱,植物萎蔫,叶片变软下垂,下部叶片开始变黄,严重时甚至完全枯萎。干旱处理时白芥幼苗叶片叶绿素含量与对照相比呈下降趋势；可溶性糖和可溶性蛋白的含量都是随着时间的持续和处理浓度的增加呈现先上升后下降的趋势；丙二醛的含量呈现上升的趋势,并且在最高浓度和最长时间的处理下达到了最大值。这三个指标都说明植物是通过这些物质含量的增加来抵御干旱胁迫。干旱处理后三种氧化还原酶的活性(超氧物歧化酶SOD、过氧化氢酶CAT和过氧化物酶POD)基本上呈现先上升后下降趋势,其中SOD和POD都是先上升后下降,而CAT变化不明显。从柠檬酸合酶基因的表达来看,短暂轻微的干旱胁迫时白芥以柠檬酸合酶表达升高来应对逆境条件,随后逐渐适应直至表达恢复。严重干旱胁迫时,表达量上升后不会再下降,揭示白芥生理受损程度严重难以恢复。柠檬酸合酶在干旱胁迫中的变化,可以间接判断三羧酸循环在干旱胁迫中起反应的方式,这对研究逆境胁迫条件下植物的抗逆性能和反应情况、揭示糖的分解和合成强度以及脂肪酸代谢等都有重要意义。更多还原

【Abstract】 The purpose of this study was to study the physiology and biochemistry response and citrate synthase gene expression of Sinapis alba seedling under drought stress. We adopted soil culture and PEG6000simulating drought stress. We had three concentration of PEG which were10%,15%,20%, there were four concentration adding CK group. In addition to there were the different time treatment gradient design, which were3days,6days,9days, and12days respectively, based on the different time of taking leaves. The experimental materials is drought resistance breed white mustard one. The physiology and biochemistry response were studied by the measurement of the chlorophyll content, the content of soluble sugar, soluble protein content, MDA and SOD, CAT, POD enzyme activity of white mustard leaves. The citrate synthase gene expression was researched through the fluorescent quantitative PCR results of gene in white mustard leaves under15%and20%PEG condition and different time.Under different concentration and different drought stress time, the external feature of white mustard had enomous differences with CK group. The stem became thinner and weaker and the plant wilted, leaves became soft and prolapsed. The bottom leaves began to become yellow firstly, and some completely withered seriously. Under drought condition, the chlorophyll content dropped contrasted to control group; the soluble sugar and soluble protein content was on the trend of decline after rising first as time continuoued and the increase of the concentration; the content of MDA showed a rising trend all the time. This three indexes showed that the plants resisted drought stress through the increase of the content of the materials. Under drought condition, the activity of the three kinds of oxidoreductase(SOD, CAT and POD) was on the trend of decline after rising basically. SOD and POD is both rises before the fall, but CAT did not change significantly, which was different.Which can be seen from citrate synthase gene expression is that white mustard accommodated environmental changes through the increase of gene expression, then the plant gradually adapted to the environment and recovered. Under severe drought stress, the expression did not fall after the rise. That is indicated that the plant physiological damage can not recover any more. From the change of citrate synthase gene expression under drought stress, we can indirectly judge the way in which Krebs cycle in the drought stress react. This is significant to the study of reaction and the synthesis and decomposition of sugar and fatty acid metabolism of plant under the adverse situation.更多还原