植物低温伤害恢复过程中的膜脂分子组成变化
李利霞
学位类型硕士
导师李唯奇
2010-01
学位授予单位中国科学院研究生院
学位专业植物学
摘要低温胁迫是限制植物生长发育和分布的主要环境因子之一。研究植物响应低温伤害的生理生化和分子机制可为提高植物耐受低温的能力提供理论依据,对农业生产实践提供帮助。生物膜是植物细胞受到低温胁迫时的主要受害部位。前人的研究证明冷驯、冰冻以及冻融等低温处理过程中细胞膜脂都发生了很大的变化。本研究将拟南芥和油菜两种对零下低温有一定抗性的植物以及水稻和黄瓜两种对零上低温敏感的植物作为研究对象,采用ESI/MS-MS和TLC等手段检测了低温伤害及伤害恢复过程中的膜脂分子组成变化。从膜脂的绝对含量来看,当拟南芥经历可以恢复的低温胁迫过程时,各类膜脂分子均变化后又恢复到对照水平。当植物经历不可恢复的低温胁迫最终死亡时,除PA(phosphatidic acid)和溶血磷脂以外的膜脂分子都发生了大规模的有序的降解,其中在冻融的过程中发生了最激烈的变化。PA在冻融的过程中大幅升高,在去冷驯过程中也开始降解,但依然显著高于对照水平;同时还出现了个别在可恢复的过程中不曾出现的分子种类。两类糖脂的变化模式是不同的:MGDG(monogalactosyldiacylglycerol)变化激烈而DGDG(digalactosyldiacylglycerol)变化缓和。通过对不同基因型的拟南芥在低温胁迫下的表现的研究,发现突变体和野生型之间的差异比较小,说明PLDα1(phospholipase Dα1)和PLDδ(phospholipase Dδ)在不可逆的低温伤害诱导的膜脂降解的过程中作用较小,有多种膜脂降解酶参与了膜脂降解过程。通过对各种膜脂的相对含量的研究发现有些膜脂种类的绝对含量下降但相对含量却在上升,说明不同的膜脂种类的降解的顺序和速率是不同的。在可逆的低温胁迫下,膜脂的双键指数变化不大,而不可逆的低温胁迫下,膜脂的双键指数持续下降。具体研究各种膜脂的双键指数的变化,发现变化并不大,说明不可逆的低温胁迫下,膜脂的双键指数持续下降,是由于双键指数高的膜脂如MGDG的相对含量的下降引起的。油菜中存在和拟南芥相似的规律。水稻和黄瓜在受到可逆和不可逆的零上低温的胁迫时,也是PA上升,其他脂类下降,说明低温诱导的膜崩解与胞内结冰关系不大。总之,当植物遭遇可逆的低温伤害时,膜脂分子可以通过调节各组分的比例来保证植物的存活,当温度恢复正常时,膜脂也得以恢复。当植物遭遇不可逆的低温伤害时,膜脂分子会大规模有序降解,可能各类膜脂分子都先降解为PA,然后PA再降解,所以PA会先大幅上升,再下降。对低温胁迫下植物坏死过程的这一规律的了解,为我们避免由低温以及别的胁迫诱导的植物坏死提供了理论依据。
资助项目Low temperature stress is one of the main environmental factors which limit plant growth, development and distribution. The physiological, biochemical and molecular mechanisms research on plant response to low temperature injury can provide theoretical basis for improving plant tolerance to low temperature,and benefit agricultural production practices. The membrane is a major injury site induced by low temperature. Previous studies have shown that membrane lipids have undergone great changes in low-temperature treatments like cold acclimation, freezing and thawing.This study used ESI / MS-MS and TLC technologies to detecte the changes of membrane lipid species in the process of low-temperature injury and injury recovery in Arabidopsis thaliana, Brassica napus, Oryza sativa (rice) and Cucumis satirus (cucumber). Arabidopsis and Brassica napus have resistance to subzero low temperature to some extent, whereas rice and cucumber are sensitive to unfreezing low temperature.When Arabidopsisexperienced reversible low temperature stress, absolute concentration of the membrane lipid species changed,while this change could back to normal after temperature returned to normal. When the plant could not be restored through the low-temperature stress and died, membrane lipid species except PA and lysophospholipids had undergone a large-scale degradation orderly, which occurred most violently in the process of thawing. PA increased significantly during thawing, and degraded during cold de-acclimation, but still significantly higher than normal level. At the same time, some new type of membrane lipid species appeared. The changing pattern of two types of glycolipids were different: MGDG changed drastically while DGDG changed moderately. On the contrast of different Arabidopsis genotypes underwent low temperature stress found that there were no significant difference between mutant-type and wild-type, indicating PLDα1 and PLDδ play a small role in low temperature process of degradation of membrane lipid induced by irreversible injury. Many phospholipase involved in lipid degradation. By the research on relative content of various lipids found that some lipids decreased in absolute concentration while increased in the relative concentration indicating the degradation order and rate of different lipids was different. Under the reversible low temperature stress, the double bond index (DBI) of membrane lipid was unchanged, while that changed continuously under the irreversible low temperature stress. Specific analysis on changes in DBI of every lipid class revealed that changes were not obvious, which indicated that under irreversible low-temperature stress, the decrease of relative concentration of some membrane lipids like MGDG which had high DBI induced the DBI of total membrane lipid to decline.There was similar discipline in Brassica napus. When rice and cucumber experienced reversible and irreversible unfreezing low-temperature stress, PA also increased and other lipids decreased, indicating low-temperature-induced membrane disintegration had little to do with intracellular ice.In short, when plant experienced reversible low-temperature injury, lipid species could regulate the ratio of each component to ensure the survival of plants. When the temperature returned to normal, the membrane lipids had also been restored. When the plants suffered irreversible damage at low temperature, the membrane lipid molecules would degrade orderly and severely. Various types of membrane lipid molecules might be first degraded to PA, then PA degraded, so PA would first significantly increase, and then decreased. The knowledge on discipline of plants response to low temperature stress on the necrotic process can provide a theoretical basis for us to avoid the plants necrosis induced by cold and other stress-induced.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16076
专题昆明植物所硕博研究生毕业学位论文
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李利霞. 植物低温伤害恢复过程中的膜脂分子组成变化[D]. 中国科学院研究生院,2010.
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