Light-harvesting Assemblies Research Articles

Grana formation in chloroplasts may promote energy transfer between photosystem II units

FEBS LettersVolume 117, Issue 1-2 p. 332-334 Full-length articleFree Access Grana formation in chloroplasts may promote energy transfer between photosystem II units Robert C. Jennings, Robert C. Jennings Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this authorFlavio M. Garlaschi, Flavio M. Garlaschi Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this authorPaolo D. Gerola, Paolo D. Gerola Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this authorGiorgio Forti, Giorgio Forti Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this author Robert C. Jennings, Robert C. Jennings Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this authorFlavio M. Garlaschi, Flavio M. Garlaschi Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this authorPaolo D. Gerola, Paolo D. Gerola Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this authorGiorgio Forti, Giorgio Forti Centro di Studio del CNR per la Biologia Cellulare e Molecolare delle Piante, Istituto di Scienze Botaniche, Via G. Colombo 60, 20133 Milano, ItalySearch for more papers by this author First published: August 11, 1980 https://doi.org/10.1016/0014-5793(80)80974-4Citations: 11AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume117, Issue1-2August 11, 1980Pages 332-334 ReferencesRelatedInformation

Differentiation of chloroplast lamellae: Light harvesting efficiency and grana development

Incomplete development of chloroplast lamellae occurred when etiolated pea plants were greened under cycles of 2 min light, 118 min dark. Although the plastids had full photochemical activities, they were nearly agranal. They were also characterized by a high quantum requirement for whole chain electron transport in low light; this is thought to be the result of unequal light absorption by incompletely developed light-harvesting assemblies of photosystem I and II and a lack of regulation of excitation energy distribution between the two photosystems. Continuous illumination induced the final stages of membrane differentiation. These stages were primarily characterized by the appearance of grana stacking and an increase in photosynthetic unit size. A biphasic decrease in quantum requirement for whole chain electron transport correlated directly with the appearance of grana during the final steps of membrane assembly. Structural organization of the membrane may be related to the light-harvesting efficiency of the membrane.

Composition of the photosystems and chloroplast structure in extreme shade plants

Chloroplasts were isolated from leaves of three species of tropical rainforest plants, Alocasia macrorrhiza, Cordyline rubra and Lomandra longifolia; these species are representative of extreme “shade” plants. It was found that shade plant chloroplasts contained 4–5 times more chlorophyll than spinach chloroplasts. Their chlorophyll a/chlorophyll b ratio was 2.3 compared with 2.8 for spinach. Electron micrographs of leaf sections showed that the shade plant chloroplasts contained very large grana stacks. The total length of partitions relative to the total length of stroma lamellae was much higher in Alocasia than in spinach chloroplasts. Freeze-etching of isolated chloroplasts revealed both the small and large particles found in spinach chloroplasts. Despite their increased chlorophyll content, low chlorophyll a/chlorophyll b ratio, and large grana, the shade plant chloroplasts were fragmented with digitonin to yield small fragments (D-144) highly enriched in Photosystem I, and large fragments (D-10) enriched in Photosystem II. The degree of fragmentation of the shade plant chloroplasts was remarkably similar to that of spinach chloroplasts, except that the subchloroplast fragments from the shade plants had lower chlorophyll a/chlorophyll b ratios than the corresponding fragments from spinach. The D-10 fragments from the shade plants had chlorophyll a/chlorophyll b ratios of 1.78-2.00 and the D-144 fragments ratios of 3.54–4.07. We conclude that Photosystems I and II of the shade plants have lower proportions of chlorophyll a to chlorophyll b than the corresponding photosystems of spinach. The lower chlorophyll a/chlorophyll b ratio of shade plant chloroplasts is not due to a significant increase in the ratio of Photosystem II to Photosystem I in these chloroplasts. The extent of grana formation in higher plant chloroplasts appears to be related to the total chlorophyll content of the chloroplast. Grana formation may simply be an means of achieving a higher density of light-harvesting assemblies and hence a more efficient collection of light quanta.