Chapter 4 - Lipid metabolism in plants

Abstract

Plants produce the majority of the world's lipids, and most animals, including humans, depend on these lipids as a major source of calories and essential fatty acids. Like other eukaryotes, plants require lipids for membrane biogenesis, as signal molecules, and as a form of stored carbon and energy. In addition, leaves and other aerial surfaces, bark, herbaceous shoots, and roots each have distinctive protective lipids that help prevent desiccation and infection. The presence of chloroplasts and related organelles in plants has a profound effect on both gross lipid composition and the flow of lipid within the cell. Fatty acid synthesis occurs not in the cytosol as in animals and fungi, but in the chloroplast and other plastids. On a whole organism basis, plants store more carbon as carbohydrate than as lipid. Since plants are not mobile, and since photosynthesis provides fixed carbon on a regular basis, plant requirements for lipid storage as an efficient, light weight energy reserve are less acute than those of animals. Plant lipids have a substantial impact on the world economy and human nutrition. More than three-quarters of the edible and industrial oils marketed annually are derived from seed and fruit triacylglycerols.