Events Surrounding the Early Development of Euglena Chloroplasts
- 1 March 1970
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 45 (3), 339-347
- https://doi.org/10.1104/pp.45.3.339
Abstract
Preillumination, followed by a dark period prior to exposure of dark-grown nondividing cells of Euglena gracilis var. bacillaris to normal lighting conditions for chloroplast development, results in potentiation, or abolishment of the usual lag in chlorophyll accumulation. The degree of potentiation is a function of the length of the preillumination period, the intensity of preilluminating light, and the length of the dark period interposed before re-exposure to continuous light for development. The optimal conditions are found to be: 90 minutes of preillumination with white light at an intensity greater than 30 microwatts per square centimeter (14 foot candles) followed by a dark period of at least 12 hours. Reciprocity is not found between duration and intensity of preilluminating light. Preillumination with blue light and red light was found to be the most effective in promoting potentiation, and the ratio of effectiveness of blue to green to red is consistent with protochlorophyll-(ide) being the photoreceptor. Although red light is effective, there is no reversal by far red light, and these facts, taken together with the effectiveness of blue light, suggest that the phytochrome system is not involved. The amount of chlorophyll formed at the end of preillumination is proportional to the resulting potentiation, suggesting that the amount of protochlorophyll(ide) removed or chlorophyll(ide) formed regulates this phenomenon. Potentiated and nonpotentiated cells show comparable rates of protochlorophyll(ide) resynthesis, suggesting that this is not the limiting factor in nonpotentiated cells. Although light is required for protochlorophyll(ide) conversion in chlorophyll synthesis, a brief preillumination seems also to initiate the production of components in the subsequent dark period which, in nonpotentiated cells, are ordinarily synthesized during the lag period under continuous illumination. These components are necessary to sustain maximal rates of subsequent chlorophyll accumulation.Keywords
This publication has 26 references indexed in Scilit:
- Changes in Enzymatic Activities in Etiolated Bean Seedling Leaves After a Brief IlluminationPlant Physiology, 1968
- RNA Metabolism During Light-Induced Chloroplast Development in EuglenaPlant Physiology, 1967
- Isolation of Phytochrome from the Alga Mesotaenium and Liverwort SphaerocarposPlant Physiology, 1967
- Studies of Chloroplast Development in Euglena. VII. Fine Structure of the Developing PlastidPlant Physiology, 1964
- PHOTOINDUCTION OF TRANSHYDROGENASE IN EUGLENA1964
- Development of bean-leaf transhydrogenase in etiolated leavesBiochimica et Biophysica Acta, 1962
- THE EFFECT OF LIGHT INTENSITY AND SUCROSE FEEDING ON THE FINE STRUCTURE IN CHLOROPLASTS AND ON THE CHLOROPHYLL CONTENT OF ETIOLATED LEAVESThe Journal of cell biology, 1962
- Effect of light on growth of black valentine bean plastidsBiochimica et Biophysica Acta, 1961
- Studies of chloroplast development in EuglenaBiochimica et Biophysica Acta, 1961
- Studies of chloroplast development in Euglena II. Photoreversal of the U.V. inhibition of green colony formationBiochimica et Biophysica Acta, 1961