|Yocum, Charles - UNIV MICHIGAN, ANN ARBOR|
Submitted to: Oxygenic Photosynthesis: The Light Reactions
Publication Type: Book / Chapter
Publication Acceptance Date: June 22, 1995
Publication Date: N/A
Interpretive Summary: Although photosynthesis performs extremely efficiently under optimal conditions, environmental factors such as extremes in temperature, too much or too little water or inadequate mineral nutrition virtually always lower the efficiency of photosynthesis under actual agricultural conditions. How well or how poorly different plant species or crop cultivars cope with specific environmental challenges is an important agronomic issue. Discovering the underlying physiological and genetic basis for both susceptibility and tolerance to specific environmental stresses is one of the most important goals of agricultural research because this is the most important step in crop improvement efforts. Underpinning research aimed at improving the photosynthetic performance of crop plants faced with environmental challenges is our understanding of the basic processes of photosynthesis. This manuscript will be the introductory chapter of an advanced, multi-authored book containing the state of the art knowledge of the photosynthetic processes of higher plants.
Technical Abstract: The photosynthetic membranes of plants perform a remarkable feat: they covert a portion of the energy available in light into the chemical energy of ATP and NADPH. In this way, photosynthetic membranes convert a very transient form of energy into forms which are stable over long periods of time, stable enough to be used at a later time for energy-requiring biochemical processes such as the reduction of CO2 to carbohydrate. In the first step in photosynthetic energy transformation, the absorption of light in the antenna array, energy is stored in the excited state of pigment molecules and used to drive a series of oxidation-reduction reactions which take place within the thylakoid membrane. The four major protein complexes within the thylakoid membrane are responsible for the conversion of energy stored as the excited state of a pigment molecule ultimately into ATP and NADPH. Three of these complexes, photosystems I & II (PS & PS II) an the cytochrome b6f complex (cyt b6f) are involved in light-driven electron and proton transfer.