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Plant Physiology 70:1242-1248 (1982) © 1982 American Society of Plant Biologists Reorganization of the Photosystem II Unit in Developing Thylakoids of Higher Plants after Transfer to Darkness 1Changes in Chlorophyll b, Light-Harvesting Chlorophyll Protein Content, and Grana StackingBiology Department, Nuclear Research Center Democritos, Greek Atomic Energy Commission, Athens, Greece
A light-dependent reversible grana stacking-unstacking process, paralleled by a reorganization of thylakoid components, has been noticed in greening etiolated bean (Phaseolus vulgaris, var. red kidney) leaves upon transfer to darkness. The reorganization, based on biochemical and biophysical criteria, involves mainly the photosystem II (PSII) unit components: upon transfer to darkness, the light-harvesting chlorophyll protein (LHCP), its 25 kilodalton polypeptide and chlorophyll b are decreased, while the CPa and its 42 kilodalton polypeptide are increased and new PSII units of smaller size are formed. This reorganization of components occurs only in thylakoids still in the process of development and not in those present in steady state conditions. It is proposed that this process does not reflect the turnover of the LHCP component per se, but a regulatory process operating during development, by which the ratio of light-harvesting to PSII reaction center components, determined by the environmental conditions, controls the photosynthetic rate.
1 Supported partly by NATO Research Grant 1869 to G. A. This article has been cited by other articles:
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