Lipid Metabolism and Photosynthesis in Fatty Acid Mutants ofArabidopsis

叶绿体的酰基脂含有高比例的三烯脂肪酸。然而，光合光反应的自由基副产物可导致多不饱和脂肪酸氧化。由于这可能会介导高度不饱和，因此推断三烯脂肪酸在支持光合作用中必须发挥一些关键作用。叶绿体中其他不寻常的脂质特征也引起了对膜结构和功能的类似猜测。为了以一种新的方式进入这一研究领域，我们分离了一系列具有叶片脂肪酸组成特异性改变的拟南芥突变体。在过去的六年里，这些研究为研究叶绿体甘油脂的合成和膜脂组成的生理意义提供了手段。本提案描述了突变体和去饱和酶基因将一起使用的实验，以产生具有逐渐更严重的类囊体脂质组成改变的植物系。这些细胞系将在一系列环境条件下使用非侵入性叶绿素荧光技术、光合电子传递分析和膜流动性测量进行研究。这些实验将提供维持叶绿体功能所需的特定脂肪酸类型的最低水平的数据。它们还应该揭示哪些光合作用过程最容易受到膜破坏的影响。这项工作将提高对膜脂代谢和光合作用的理解，这是修改这些过程以提高植物生产力的重要先决条件。＊＊＊

9407902 Browse The acyl lipids of chloroplasts contain characteristically high proportions of trienoic fatty acids. However, the free radical by- products of the photosynthetic light reactions can lead to oxidation of polyunsaturated fatty acids. Because this might be expected to mediate against a high degree of unsaturation, it has been inferred that trienoic fatty acids must have some crucial role in supporting photosynthesis. Other unusual lipid features typical of chloroplasts have provoked similar speculation about membrane structure and function. To approach this research area in a novel way, a series of Arabidopsis mutants with specific alterations in leaf fatty acid composition have been isolated. In the last six years, these have provided a means to study both the synthesis of chloroplast glycerolipids and the physiological significance of membrane lipid composition. This proposal describes experiments in which the mutants and the desaturase genes will be used together to produce plant lines with progressively more severe alterations in thylakoid lipid composition. These lines will be studied under a range of environmental conditions using non-invasive chlorophyll fluorescence techniques, assays of photosynthetic electron transport, and measurements of membrane fluidity. These experiments will provide data on the minimum levels of particular fatty acid types that are needed to sustain chloroplast function. They should also reveal which photosynthetic processes are most susceptible to membrane disruption. The improved understanding of membrane lipid metabolism and photosynthesis that will result from this work are important prerequisites to modifying these processes for increased plant productivity. ***