Plant Membranes: A Biophysical Approach to Structure, Development and Senescence

This book provides the reader with a multidisciplinary approach to an understanding of the function of various plant membrane categories as influenced on the one hand by their structural components and, on the other, by micro- and macro-environmental conditions. Specific topics discussed under relevant headings include ion channeling, plant hormone receptors and biophysical aspects of trans-membrane water movements. While the text essentially is a biophysical one, drawing on contemporary physical concepts, these are couched in terms -- accompanied by a wealth of detailed diagrams -- which are understandable to the average plant biologist. The material presented is divided into three parts. Part 1 is a comprehensive description of the various plant membrane components -- lipids, proteins, sterols and water; Part 2 deals with both theoretical and applied aspects of plant membrane biophysics; Part 3, basing upon principles outlined in the previous sections describes `the membrane in action'. The processes in this part include the role of calcium in the membrane, phospholytic and lipolytic enzymes, membrane acclimation to chilling and freezing, tomoplast and plasma membranes of guard cell, and trans-membrane signal transduction in development and senescence.

The plasma membrane is at once the window through which the cell senses the environment and the portal through which the environment influences the structure and activities of the cell. Its importance in cellular physiology can thus hardly be overestimated, since constant flow of materials between cell and environment is essential to the well-being of any biological system. The nature of the materials mov- ing into the cell is also critical, since some substances are required for maintenance and growth, while others, because of their toxicity, must either be rigorously excluded or permitted to enter only after chemical alteration. Such alteration frequently permits the compounds to be sequestered in special cellular compartments having different types of membranes. This type of homogeneity, plus the fact that the wear and tear of transmembrane molecular traffic compels the system to be constantly monitored and repaired, means that the membrane system of any organism must be both structurally complex and dy- namic. Membranes have been traditionally difficult to study because of their fragility and small diameter. In the last several decades, however, remarkable advances have been made because of techniques permit- ting the bulk isolation of membranes from homogenized cells. From such isolated membranes have come detailed physical and chemical analyses that have given us a detailed working model of membrane. We now can make intelligent guesses about the structural and func- tional interactions of membrane lipids, phospholipids, proteins, sterols and water.

1. Introduction. Part One: The Building Blocks of the Membrane. 2. Membrane Fatty Acyl Tailgroups. 3. Glycerolipid and Sphingolipid Headgroups. 4. Sterols. 5. Membrane Proteins. 6. Membrane Water. Part Two: Biophysical Aspects of Membrane Structure and Function. 7. Plant Membrane Biophysics in Development and Senescence. Part Three: The Membrane in Action. 8. The Role of Calcium in the Membrane. 9. Membrane-Associated Phospholytic and Lipolytic Enzymes. 10. Responses of Plant Membranes in Chilling and Freezing. 11. The Tonoplast and Plasma Membrane of Guard Cells. 12. Signal Transduction, Ca²⁺-triggered Membrane Glycerolipid Turnover and Growth/Senescence Equilibria. Epilogue. List of Abbreviations. Subject Index.