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.

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.

scholarly journals Regulation of electron transport is essential for photosystem I stability and plant growth

2019 ◽  
Author(s):  
Mattia Storti ◽  
Anna Segalla ◽  
Marco Mellon ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Nadh Dehydrogenase ◽  
Physcomitrella Patens ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Type I ◽  
Growth Reduction ◽  
Light Regimes ◽  
Photosynthetic Organisms

AbstractLife depends on the ability of photosynthetic organisms to exploit sunlight to fix carbon dioxide into biomass. Photosynthesis is modulated by pathways such as cyclic and pseudocyclic electron flow (CEF and PCEF). CEF transfers electrons from photosystem I to the plastoquinone pool according to two mechanisms, one dependent on proton gradient regulators (PGR5/PGRL1) and the other on the type I NADH dehydrogenase (NDH) complex. PCEF uses electrons from photosystem I to reduce oxygen; in several groups of photosynthetic organisms but not in angiosperms, it is sustained by flavodiiron proteins (FLVs). PGR5/PGRL1, NDH and FLVs are all active in the moss Physcomitrella patens, and mutants depleted in these proteins show phenotypes under specific light regimes. Here, we demonstrated that CEF and PCEF exhibit strong functional overlap and that when one protein component is depleted, the others can compensate for most of the missing activity. When multiple mechanisms are simultaneously inactivated, however, plants show damage to photosystem I and strong growth reduction, demonstrating that mechanisms for the modulation of photosynthetic electron transport are indispensable.

scholarly journals Increasing cyclic electron flow mediated by NDH is related to heat tolerance under low light in grape leaves

2017 ◽  
Author(s):  
Yongjiang Sun ◽  
Guimei Hao ◽  
Yulu Gao ◽  
Yuanpeng Du ◽  
Xinhong Yang ◽  
...  
Keyword(s):  
Heat Stress ◽  
Methyl Viologen ◽  
Physiological Function ◽  
Electron Flow ◽  
D1 Protein ◽  
Cyclic Electron Flow ◽  
Half Time ◽  
Low Light ◽  
Psii Photochemistry ◽  
Critical Temperature Tc

Examination of the effects of high temperature (42 °C) on the photoinhibition of photosystem II (PSII) in grape leaves revealed that the extent of photoinhibition of PSII was lower in the light (200 μmol m-2 s-1) than in the dark. Heat stress in the dark induced severe injury in the grapevines, as determined by the critical temperature (Tc). The maximal efficiency of PSII photochemistry (Fv/Fm) decreased significantly in the dark, but it decreased much less in the light. In addition, there was a lower level of degradation of the D1 protein in the light than in the dark. Furthermore, the NAD(P)H dehydrogenase (NDH)-dependent cyclic electron flow (CEF) was remarkably enhanced in the light, but it was suppressed in the dark. The half-time of P700+ re-reduction (t1/2) was reduced moer in in the light than in the dark during heat stress. Compared to the control leaves, the antimycin A (AA)-treated leaves showed much less of a decrease in Fv/Fm in the light than in the dark during heat stress; however, this increase seemed to disappear in methyl viologen (MV)-treated leaves. Based on these results, we propose a significant physiological function of the NDH-dependent CEF pathway under low light is the protection of PSII against heat-induced photoinhibition.

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.

scholarly journals Increasing cyclic electron flow mediated by NDH is related to heat tolerance under low light in grape leaves

2017 ◽  
Author(s):  
Yongjiang Sun ◽  
Guimei Hao ◽  
Yulu Gao ◽  
Yuanpeng Du ◽  
Xinhong Yang ◽  
...  
Keyword(s):  
Heat Stress ◽  
Methyl Viologen ◽  
Physiological Function ◽  
Electron Flow ◽  
D1 Protein ◽  
Cyclic Electron Flow ◽  
Half Time ◽  
Low Light ◽  
Psii Photochemistry ◽  
Critical Temperature Tc

Examination of the effects of high temperature (42 °C) on the photoinhibition of photosystem II (PSII) in grape leaves revealed that the extent of photoinhibition of PSII was lower in the light (200 μmol m-2 s-1) than in the dark. Heat stress in the dark induced severe injury in the grapevines, as determined by the critical temperature (Tc). The maximal efficiency of PSII photochemistry (Fv/Fm) decreased significantly in the dark, but it decreased much less in the light. In addition, there was a lower level of degradation of the D1 protein in the light than in the dark. Furthermore, the NAD(P)H dehydrogenase (NDH)-dependent cyclic electron flow (CEF) was remarkably enhanced in the light, but it was suppressed in the dark. The half-time of P700+ re-reduction (t1/2) was reduced moer in in the light than in the dark during heat stress. Compared to the control leaves, the antimycin A (AA)-treated leaves showed much less of a decrease in Fv/Fm in the light than in the dark during heat stress; however, this increase seemed to disappear in methyl viologen (MV)-treated leaves. Based on these results, we propose a significant physiological function of the NDH-dependent CEF pathway under low light is the protection of PSII against heat-induced photoinhibition.

scholarly journals In-vivo quantification of electron flow through photosystem I – Cyclic electron transport makes up about 35% in a cyanobacterium

2021 ◽  
Vol 1862 (3) ◽  
pp. 148353
Author(s):  
Marius L. Theune ◽  
Sarah Hildebrandt ◽  
Anja Steffen-Heins ◽  
Wolfgang Bilger ◽  
Kirstin Gutekunst ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Electron Flow ◽  
Cyclic Electron Transport ◽  
Flow Through
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