Light as an Energy Source and Information Carrier in Plant Physiology

A NATO Advanced Study Institute on "Light as Energy Source and Information Carrier in Plant Photo physiology" was held at Volterra, Italy, from September 26 to October 6, 1994, in order to consider the fundamental role that light plays in plant growth and development. This book summarises the main lectures given at this meeting which concentrated on both photochemical energy conversion and signalling (photosensing) aspects. Light harvesting and conversion into chemical energy in photosynthesis occurs at the level of chlorophyll/carotenoid containing photosystems in plants. Pigments are non­ covalently bound to a variety of polypeptides which serve as a specific scaffolding, necessary to determine the energy coupling between pigments and thus allowing rapid excitation energy trasfer from the antenna to the special reaction centre chlorophylls. Data from transient, time resolved spectroscopies, in the femtosecond and picosecond domain, together with model calculations, suggest that this process occurs in the 20-100 picosecond time span. The special ~ll u~ture of reaction centre complexes, ensures rapid primary charge separation, probably in the order of 1-3 picoseconds, with subsequent charge stabilisation reactions proceeding in the hundreds of picoseconds range. The recently resolved crystallographic structure of LHCII, the principal antenna complex of plants, allows precise determination of pigment-pigment distances and thus permits calculation of approximate chlorophyll-chlorophyll Forster hopping rates, which are in good agreement with time resolved measurements.

Inhalt

Photosynthesis: An Overview; G. Forti. Photosynthetic Electron Transfer and Energy Transduction in Plants; D.R. Ort, J. Whitmarsh. Specific Features of Excitation Migration in Photosynthesis; A.Yu. Borisov. Biochemistry and Molecular Biology of Pigment Binding Protein; R. Bassi, et al. Spectral Heterogeneity and Energy Equilibration in Higher Plant Photosystems; R.C. Jennings, et al. Photosynthetic Reaction Centers; P. Mathis. Photoinhibition of Photosynthesis; N.R. Baker. Nonphotochemical Quenching of Chlorophyll Fluorescence; P. Horton. Regulation of Excited States in Photosynthesis of Higher Plants; J.M. Briantais. Chirally Organized Macrodomains in Thylakoid Membranes: Possible Structural and Regulatory Roles; G. Garab. Interaction of UV Radiation with the Photosynthetic Systems; J.F. Bornman. Molecular Basis of Photoreception; F. Lenci, et al. Photomorphogenic Systems; W.R. Briggs, et al. Overview of Photosensing in Plant Physiology; W. Haupt. Light Signal Transduction Mediated by Phytochromes; D. Sommer, P.S. Song. Light Penetration into the Canopy of Terrestrial Ecosystems; M.G. Holmes. Interception of Light and Light Penetration in Plant Tissues; M.G. Holmes. Photosensory Transduction in Flagellated Algae; R. Marangoni, et al. Action Spectroscopy; F. Ghetti, G. Checcucci. 5 additional articles. Index.