Lipid Metabolism and Photosynthesis in Fatty Acid Mutants ofArabidopsis

9407902浏览叶绿体的酰基脂质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的氧化。 因为这可能是预期调解对高度不饱和，它已被推断，三烯脂肪酸必须有一些支持光合作用的关键作用。 叶绿体特有的其他不寻常的脂质特征也引起了人们对膜结构和功能的类似猜测。 为了以一种新的方式接近这一研究领域，已经分离出一系列在叶脂肪酸组成中具有特定改变的拟南芥突变体。 在过去的六年中，这些提供了一种手段来研究叶绿体甘油脂的合成和膜脂组成的生理意义。 该建议描述了将突变体和去饱和酶基因一起用于产生类囊体脂质组成逐渐发生更严重改变的植物系的实验。 这些线将在一系列环境条件下使用非侵入性叶绿素荧光技术，光合电子传递的测定，和膜流动性的测量进行研究。 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。 膜脂代谢和光合作用，将导致这项工作的重要先决条件，修改这些过程，提高植物生产力的理解。 ***

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. ***