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昆明植物所硕博研究生... [1]

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2010 [1]

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KIB OpenIR

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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.

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