scholarly journals Cyclic Electron Flow around Photosystem I Promotes ATP Synthesis Possibly Helping the Rapid Repair of Photodamaged Photosystem II at Low Light

2018 ◽  
Vol 9 ◽  
Author(s):  
Wei Huang ◽  
Ying-Jie Yang ◽  
Shi-Bao Zhang ◽  
Tao Liu
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Atp Synthesis ◽  
Cyclic Electron Flow ◽  
Low Light ◽  
Rapid Repair

DCMU-Induced Fluorescence Changes and Photodestruction of Pigments Associated with an Inhibition of Photosystem I Cyclic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 351-353 ◽  
Author(s):  
Stuart M. Ridley ◽  
Peter Horton
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Dose Response ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Cyclic Flow ◽  
Working Hypothesis ◽  
Dose Responses

Diuron (DCMU) induces the photodestruction of pigments, which is the initial herbicidal symptom. As a working hypothesis, it is proposed that this symptom can only be produced when the herbicide dose is sufficiently high to inhibit not only photosystem II electron transport almost completely, but also inhibit (through over oxidation) the natural cyclic electron flow associated with photosystem I as well. Using freshly prepared chloroplasts, studies of DCMU-induced fluorescence changes, and dose responses for inhibition of electron transport, have been compared with a dose response for the photodestruction of pigments in chloroplasts during 24 h illumination. Photodestruction of pigments coincides with the inhibition of cyclic flow.

Inhibition of Photosynthetic Electron Transport by Halogenated 4-Hydroxy-pyridines

1985 ◽  
Vol 40 (5-6) ◽  
pp. 391-399 ◽  
Author(s):  
A. Trebst ◽  
B. Depka ◽  
S. M. Ridley ◽  
A. F. Hawkins
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Essential Element ◽  
Photosynthetic Electron Transport ◽  
Cyclic Electron Flow ◽  
Acceptor Side

Abstract Herbicidal halogen substituted 4-hydroxypyridines are inhibitors of photosynthetic electron flow in isolated thylakoid membranes by interfering with the acceptor side of photosystem II. Tetrabromo-4-hydroxypyridine, the most active compound found, has a pI50-value of 7.6 in the inhibition of oxygen evolution in both the reduction of an acceptor of photosystem I and an acceptor of photosystem II. The new inhibitors displace both metribuzin and ioxynil from the membrane. The 4-hydroxypyridines, like ioxynil, have unimpaired inhibitor potency in Tristreated chloroplasts, whereas the DCMU-type family of herbicides does not. It is suggested that 4-hydroxypyridines are complementary to phenol-type inhibitors, and a common essential element is proposed. The 4-hydroxypyridines do not inhibit photosystem I or non-cyclic electron flow through the cytochrome b/f complex. But they do have a second inhibition site in photosynthetic electron transport since they inhibit ferredoxin-catalyzed cyclic electron flow, indicating an antimycin-like property. A comparison of the in vitro potency of the compounds with the in vivo potency shows no correlation. A major herbicidal mode of action of the group is related to the inhibition of carotenoid synthesis, and access to the chloroplast lamellae in vivo for inhibition of electron transport may be restricted.

Salt Enhances Photosystem I Content and Cyclic Electron Flow via NAD(P)H Dehydrogenase in the Halotolerant Cyanobacterium Aphanothece halophytica

1996 ◽  
Vol 23 (3) ◽  
pp. 321 ◽  
Author(s):  
T Hibino ◽  
BH Lee ◽  
AK Rai ◽  
H Ishikawa ◽  
H Kojima ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
O2 Evolution ◽  
Aphanothece Halophytica ◽  
Protein Levels ◽  
Photosynthetic O2 Evolution ◽  
Electron Donation ◽  
Halotolerant Cyanobacterium

To uncover the adaptation mechanisms of photosystems for halotolerance, changes in stoichiometry and activity of photosystems in response to changes of salinities were examined in a halotolerant cyanobacterium, Aphanothece halophytica. Photosynthetic O2 evolution was high even at high salinities. O2 evolution activity increased with increasing external concentration of NaCl, reached a maximum at 1.5 M NaCl, and then decreased. Similar salt dependence was observed for photosystem II activity. On the other hand, photosystem I activity increased concomitantly with increase in salinity. Photoacoustic measurements indicated that appreciable energy storage by photosystem I mediated cyclic electron flow at high salinities. Significant electron donation to photosystem I reaction centres through NAD(P)H-dehydrogenase complexes was observed in high salt media. The contents of cytochrome b6/f and photosystem II were almost constant under various salinity conditions, whereas the levels of chlorophyll α, photosystem I, soluble cytochrome c-553, and NAD(P)H-dehydrogenase increased in the cells grown with high salinities. These results indicate that salt specifically induces an increase of protein levels involving cyclic electron flow around photosystem I that may entail an important role for adaptation of Aphanothece halophytica cells to high salinities.

scholarly journals Photosystem I cyclic electron flow via chloroplast NADH dehydrogenase-like complex performs a physiological role for photosynthesis at low light

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Wataru Yamori ◽  
Toshiharu Shikanai ◽  
Amane Makino
Keyword(s):  
Electron Transport ◽  
Light Intensity ◽  
Photosystem I ◽  
Nadh Dehydrogenase ◽  
Physiological Function ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Cyclic Electron Transport ◽  
Low Light ◽  
Ps I

Abstract Cyclic electron transport around photosystem I (PS I) was discovered more than a half-century ago and two pathways have been identified in angiosperms. Although substantial progress has been made in understanding the structure of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates one route of the cyclic electron transport pathways, its physiological function is not well understood. Most studies focused on the role of the NDH-dependent PS I cyclic electron transport in alleviation of oxidative damage in strong light. In contrast, here it is shown that impairment of NDH-dependent cyclic electron flow in rice specifically causes a reduction in the electron transport rate through PS I (ETR I) at low light intensity with a concomitant reduction in CO2 assimilation rate, plant biomass and importantly, grain production. There was no effect on PS II function at low or high light intensity. We propose a significant physiological function for the chloroplast NDH at low light intensities commonly experienced during the reproductive and ripening stages of rice cultivation that have adverse effects crop yield.

Cyclic electron flow around photosystem I is enhanced at low pH

2014 ◽  
Vol 83 ◽  
pp. 194-199 ◽  
Author(s):  
Teena Tongra ◽  
Sudhakar Bharti ◽  
Anjana Jajoo
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Low Ph ◽  
Cyclic Electron Flow

scholarly journals PsaE Is Required for in Vivo Cyclic Electron Flow around Photosystem I in the Cyanobacterium Synechococcus sp. PCC 7002

1993 ◽  
Vol 103 (1) ◽  
pp. 171-180 ◽  
Author(s):  
L. Yu ◽  
J. Zhao ◽  
U. Muhlenhoff ◽  
D. A. Bryant ◽  
J. H. Golbeck
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Synechococcus Sp

scholarly journals Electron Flow between Photosystem II and Oxygen in Chloroplasts of Photosystem I-deficient Algae Is Mediated by a Quinol Oxidase Involved in Chlororespiration

2000 ◽  
Vol 275 (23) ◽  
pp. 17256-17262 ◽  
Author(s):  
Laurent Cournac ◽  
Kevin Redding ◽  
Jacques Ravenel ◽  
Dominique Rumeau ◽  
Eve-Marie Josse ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Quinol Oxidase
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