Life on Earth depends on plant photosynthesis, so it is vital that we fully understand all the component systems that contribute to photosynthetic function and how these respond to alterations in environmental parameters. Despite considerable research effort over the last twenty years, knowledge of how the lipid composition of the photosynthetic (thylakoid) membrane facilitates photosynthesis remains rudimentary. This project aims to understand the physical characteristics of thylakoid lipids, the biochemistry and regulation of lipid synthesis, and the particular lipid requirements for chloroplast biogenesis and function. The project will use the full range of biochemical, molecular and genetic techniques to investigate mutants of the model plant, Arabidopsis, in which different changes in membrane lipid composition are associated with dramatic phenotypes. The knowledge gained will help scientists predict the likely consequences of environmental changes on plant growth and crop productivity. Eventually it will be possible to manipulate membrane lipid composition of plants to better suit particular environmental conditions, such as those that may develop during global warming. Because photosynthesis is central to plant productivity, the extensive temperature-dependent effects observed in the mutants have wide implications for understanding the temperature responses of plants, and agricultural production systems. Furthermore, the improved understanding of chloroplast structure and photosynthetic function that will result from this research is an important prerequisite to modifying photosynthesis for increased plant productivity. This project will also provide opportunities for graduate and undergraduate students to receive training and experience in plant biology research relevant to agriculture, forestry and other fields of plant production. In support of open and cooperative science, the mutant stocks and other resources developed in this project will be freely available from established stock centers and from the principal investigator, directly.