【作者】 代玉华；

【导师】 孟庆伟； 赵世杰；

【作者基本信息】 山东农业大学 ， 植物学， 2003， 硕士

【摘要】 本试验以冷敏感植物黄瓜（津研四号）幼苗叶片为材料，研究了黄瓜叶片类囊体膜脂脂肪酸与光抑制及植物抗冷性之间的关系。并辅以抗冷性较强的鲁梅克斯为材料，探讨了不同抗冷性植物在低温弱光下的生理变化。主要结果如下：1．低温弱光及其恢复期间光抑制与膜脂脂肪酸的关系低温弱光处理5天后，黄瓜叶片Fv/Fm和ФPSII明显下降，在适宜条件下恢复1天，二者基本恢复到对照水平。同时，黄瓜叶片类囊体膜中多聚不饱和脂肪酸含量与Fv/Fm相关系数达84.91％，说明多聚不饱和脂肪酸与光抑制及其恢复过程关系密切。 2．低温弱光处理对不同抗冷性植物叶绿素荧光参数和膜脂脂肪酸的影响通过比较抗冷性较强的鲁梅克斯和典型冷敏感植物黄瓜在低温弱光条件下叶绿素荧光参数和磷脂酰甘油脂肪酸的变化，探讨与植物抗冷性有关的脂肪酸种类。结果表明抗冷性较强的鲁梅克斯在低温弱光下PSII光抑制程度远不如黄瓜严重，其PG中16:1(3t)含量的下降程度也较小，说明鲁梅克斯天线复合体的结构比较稳定。而且，低温胁迫期间鲁梅克斯叶片PG饱和脂肪酸含量明显下降，有利于降低膜脂相变温度。3．低温弱光胁迫对高温预处理黄瓜类囊体膜脂和叶绿素荧光参数的影响比较黄瓜幼苗进行低温锻炼和高温预处理后的膜脂变化，结果显示低温锻炼促进了18:2向18:3的转变，而高温预处理则促进了18:1向18:2的转变。将黄瓜高温（32℃）预处理3天，然后再进行低温弱光处理。在低温弱光胁迫期间，高温预处理后黄瓜光抑制程度较对照明显减轻，膜脂总不饱和脂肪酸含量经高温预处理后降低，但在胁迫期间明显增加，有利于增大类囊体膜的流动性，说明高温预处理在一定程度上起到了锻炼的作<WP=6>用。但低温弱光胁迫5天后，高温预处理黄瓜叶片的叶绿素降低程度较对照更严重，PG饱和脂肪酸含量的上升对降低膜脂相变温度不利。4．短期低温处理过程中不同光强对黄瓜叶片光抑制与膜脂脂肪酸的影响在低温（10℃）与不同光强处理过程中，强光下黄瓜PSII的最大光化学效率始终低于弱光处理的，即低温条件下强光造成的光抑制更严重。然而，低温胁迫8小时后，强光下黄瓜叶片膜脂总不饱和脂肪酸含量上升，PG饱和脂肪酸含量稍微下降，以上变化都有利于减轻低温光抑制。从短期低温（8小时）和长期低温（5天）过程中膜脂的变化与光抑制程度的相关性表现不同，推测黄瓜幼苗依靠类囊体膜脂脂肪酸的变化减轻光抑制需要一定的时间才能发挥作用。此外，类脂MGDG、DGDG中18:3组分在弱光和强光下的变化相反，可见低温下MGDG、DGDG中形成该组分的合成过程与去饱和过程对光强的变化非常敏感。更多还原

【Abstract】 The relationship among thylakoid membrane lipids, photoinhibition and cold resistance was investigated under low temperature stress in chilling-sensitive cucumber (Cucumis sativus L. cv. Jin-yan 4) leaves. In addition, physiological changes of cucumber and rumex that with different sensitivity to low temperature under low temperature and weak light were also studied. The main results were as follows:1. Relationship between photoinhibition and membrane lipid fatty acids during low temperature and weak light treatment and recovery.Both Fv/Fm and ФPSII of cucumber leaves decreased obviously after 5 day low temperature and weak light treatment, and recovered in proper condition in one day. It was interesting to observe that polyunstatured fatty acids was closely related to recovery of photoinhibition. 2. Physiological changes in plants with different sensitivity to low temperature under low temperature and weak light. Difference in changes of chlorophyll fluorescence and fatty acid composition of PG in chilling-sensitive cucumber and chilling-resistant rumex under low temperature and weak light was conducted. Results showed that damage of PSII in cucumber was more seriously than that in rumex. 16:1(3t)<WP=8>of PG in rumex decreased less than that in cucumber under stress, which indicated that degradation of LHCII oligmer was slighter in rumex. Besides, the content of saturated fatty acids of PG in rumex decreased significantly under stress, which is benefit to decrease the temperature of membrane lipid phase transitions.3. Effects of low temperature and weak light on thylakoid membrane lipids and chlorophyll fluorescence in high temperature pre- treatment and control cucumber leavesChanges of membrane lipids in cucumber leaves were analyzed after cold-hardening and high temperature pre-treatment. Results indicated cold-hardening stimulated conversion of 18:2 to 18:3, while high temperature pre-treatment enhanced in conversion of 18:1 to 18:2. The pre-treatment (3 days at 32℃) and the control cucumbers were moved to low temperature and weak light. Changes of chlorophyll fluorescence and membrane lipids suggested that high temperature pre-treatment improved the chilling resistence of cucumber. Photoinhibition of pre-treatment cucumber leaves was slighter compared with control during low temperature and weak light. The increase of unsaturated fatty acids of membrane lipids resulted in increasing thylakoid membrane fluidity. However, degradation of chlorophyll in high temperature pre-treatment cucumber leaves was more seriously than that in control, and the increase of unstaturated fatty acids of PG in pre-treatment cucumber was not benefit to decrease in temperature of membrane lipid phase transitions.4. Effect of light intensity on fatty acid composition of thylakoid membrane lipids under short time treatment of low temperature During low temperature(10℃) treatment, the PSII maximumal photo-<WP=9>chemical efficiency (Fv/Fm) was higher in cucumber leaves under strong light compared to that under weak light, implying that srong light aggravated photoinhibition. However, the increase of polyunstasurated fatty acids and the slight decrease of unstasurated fatty acids of PG in cucumber leaves under strong light were beneficial to alleviating photoinhibition after 8h stress of low temperature. According to the different relation between membrane lipids and photoinhibition during long (5 days) and short (8 hours) time treatment of low temperature, it was deduced that alleviation of photoinhibition by changes in fatty acid composition of thylakoid membrane lipids in cucumber leaves need certain time. In addition, 18:3 of MGDG and DGDG under strong and weak light changed to the contrary, indicating that synthesized and unsaturated process of 18:3 in MGDG and DGDG were sensitive to light intensity.更多还原