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LIGHT STIMULATED STARCH DEGRADATION IN PLASTIDS AND LEAF MORPHOGENESIS * †
Author(s) -
Klein W. H.,
Price L.,
Mitrakos K.
Publication year - 1963
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1963.tb08219.x
Subject(s) - plastid , biology , starch , organelle , amyloplast , chlorophyll , chloroplast , botany , seedling , darkness , biophysics , microbiology and biotechnology , biochemistry , gene
Summary The problem of chlorophyll synthesis cannot be completely isolated from the many other physiological processes occurring in the plant cell. Exogenous and endogenous factors which have a profound effect on the developing chlorophyll synthesizing mechanism primarily manifest themselves in the development of plastids. As the proplastid matures, at various stages of its development it becomes subject to new environmental influences. This is evident through the variable response observed with ageing. The germinating seedling and its proplastids do not exhibit the photosensitive response that is found in slightly older plants. Tt would appear, therefore, that during the ontogeny of these light responsive organelles, the various endo‐ and exoplastid biochemical systems which enable them to function in their eventual role as synthesizing centers within the cell are not organized simultaneously, but rather follow a sequence of developmental steps. Finally, when these systems are all complete, the plastid is poised for dynamic changes to occur under the influence of radiant energy. The preliminary data presented have indicated a partially light dependent carbohydrate degradatioii in etiolated seedlings. These changes may be of considerable significance i n explaining various photomorphogenic responses. Most particularly, the light induced disappearance of starch from the developing plastid is readily observed and may be bio‐chemically determined in less than 12 hr. Further details on the kinetics and time course of this light induced degradation of starch may establish the fundamental nature of this reaction in its role in the many cellular morphological responses.