scholarly journals Increased Air Temperature during Simulated Autumn Conditions Impairs Photosynthetic Electron Transport between Photosystem II and Photosystem I

2008 ◽  
Vol 147 (1) ◽  
pp. 402-414 ◽  
Author(s):  
Florian Busch ◽  
Norman P.A. Hüner ◽  
Ingo Ensminger
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Air Temperature ◽  
Photosystem I ◽  
Photosynthetic Electron Transport

The site of electron transport inhibition by bentazon (3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide) in isolated chloroplasts

1982 ◽  
Vol 60 (4) ◽  
pp. 409-412 ◽  
Author(s):  
Rungsit Suwanketnikom ◽  
Kriton K. Hatzios ◽  
Donald Penner ◽  
Duncan Bell
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Acceptor ◽  
Photosynthetic Electron Transport ◽  
Primary Electron ◽  
Photochemical Reactions ◽  
Spinacea Oleracea ◽  
Primary Electron Acceptor ◽  
Isolated Chloroplasts

The effect of bentazon (3-isopropyl-1H-2,1,3-benzathiadiazin-(4)3H-one 2,2-dioxide) on various photochemical reactions of isolated spinach (Spinacea oleracea L.) chloroplasts was studied at concentrations 0, 5, 15, 45, and 135 μM. Bentazon at a concentration of 135 μM strongly inhibited uncoupled electron transport from water to ferricyanide or to methylviologen with inhibition percentages greater than 90%. Photosystem II mediated electron transport from water to oxidized diaminodurene, with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) blocking photosystem I, was also strongly inhibited by bentazon at 135 μM but less with lower concentrations of bentazon. Photosystem I mediated transfer of electrons from diaminodurene to methylviologen, with 3,4-dichlorophenyl-1,1-dimethylurea (DCMU) blocking photosystem II, was not inhibited by bentazon at any concentration examined. Transfer of electrons from catechol to methylviologen in hydroxylamine-treated chloroplasts was inhibited by bentazon, and the inhibition percentages were again concentration dependent. The data indicate that the site of bentazon inhibition of the photosynthetic electron transport is at the reducing side of photosystem II, between the primary electron acceptor Q and plastoquinone.

scholarly journals The effects of high concentrations of salts on photosynthetic electron transport in spinach (Spinacia oleracea) chloroplasts

1982 ◽  
Vol 204 (3) ◽  
pp. 705-712 ◽  
Author(s):  
A C Stewart
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Spinacia Oleracea ◽  
Photosynthetic Electron Transport ◽  
Potassium Citrate ◽  
O2 Evolution ◽  
Hofmeister Series ◽  
Reaction Centre ◽  
High Concentrations

1. Photosynthetic electron transport from water to lipophilic Photosystem II acceptors was stimulated 3-5-fold by high concentrations (greater than or equal to 1 M) of salts containing anions such as citrate, succinate and phosphate that are high in the Hofmeister series. 2. In trypsin-treated chloroplasts, K3Fe(CN)6 reduction insensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea was strongly stimulated by high concentrations of potassium citrate, but there was much less stimulation of 2,6-dichloroindophenol reduction in Tris-treated chloroplasts supplied with 1,5-diphenylcarbazide as artificial donor. The results suggest that the main site of action of citrate was the O2-evolving complex of Photosystem II. 3. Photosystem I partial reactions were also stimulated by intermediate concentrations of citrate (up to 2-fold stimulation by 0.6-0.8 M-citrate), but were inhibited at the highest concentrations. The observed stimulation may have been caused by stabilizaton of plastocyanin that was complexed with the Photosystem I reaction centre, 4. At 1 M, potassium citrate protected O2 evolution against denaturation by heat or by the chaotropic agent NaNO3. 5. It is suggested that anions high in the Hofmeister series stimulated and stabilized electron transport by enhancing water structure around the protein complexes in the thylakoid membrane.

On a new inhibitor of photosynthetic electron-transport in isolated chloroplasts

1970 ◽  
Vol 25 (10) ◽  
pp. 1157-1159 ◽  
Author(s):  
A. Trebst ◽  
E. Harth ◽  
W. Draber
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
High Concentration ◽  
Ferricyanide Reduction ◽  
The Hill ◽  
Photosystem I And Ii ◽  
Isolated Chloroplasts

A halogenated benzoquinone has been found to inhibit the photosynthetic electron transport system in isolated chloroplasts. 2·10-6ᴍ of dibromo-thymoquinone inhibit the Hill- reaction with NADP, methylviologen or anthraquinone to 100%, but do not effect the photoreduction of NADP at the expense of an artificial electron donor. The Hill - reaction with ferricyanide is inhibited even at the high concentration of 2·10-5ᴍ of dibromo-thymoquinone to only 60%. The remaining reduction in the presence of the inhibitor reflects the rate of ferricyanide reduction by photosystem II. It is concluded that the inhibition of electron transport by the quinone occurs between photosystem I and II and close to or at the functional site of plastoquinone.

scholarly journals Polymer-Modified Single-Walled Carbon Nanotubes Affect Photosystem II Photochemistry, Intersystem Electron Transport Carriers and Photosystem I End Acceptors in Pea Plants

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5958
Author(s):  
Nia Petrova ◽  
Momchil Paunov ◽  
Petar Petrov ◽  
Violeta Velikova ◽  
Vasilij Goltsev ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Transport Chain ◽  
Photosynthetic Electron Transport ◽  
Single Walled Carbon Nanotubes ◽  
Donor Side ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain ◽  
Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNT) have recently been attracting the attention of plant biologists as a prospective tool for modulation of photosynthesis in higher plants. However, the exact mode of action of SWCNT on the photosynthetic electron transport chain remains unknown. In this work, we examined the effect of foliar application of polymer-grafted SWCNT on the donor side of photosystem II, the intersystem electron transfer chain and the acceptor side of photosystem I. Analysis of the induction curves of chlorophyll fluorescence via JIP test and construction of differential curves revealed that SWCNT concentrations up to 100 mg/L did not affect the photosynthetic electron transport chain. SWCNT concentration of 300 mg/L had no effect on the photosystem II donor side but provoked inactivation of photosystem II reaction centres and slowed down the reduction of the plastoquinone pool and the photosystem I end acceptors. Changes in the modulated reflection at 820 nm, too, indicated slower re-reduction of photosystem I reaction centres in SWCNT-treated leaves. We conclude that SWCNT are likely to be able to divert electrons from the photosynthetic electron transport chain at the level of photosystem I end acceptors and plastoquinone pool in vivo. Further research is needed to unequivocally prove if the observed effects are due to specific interaction between SWCNT and the photosynthetic apparatus.

Energy Conservation in Photoreductions by Photosystem II. Reversal of Dibromothymoquinone Inhibition of Hill-Reactions by Phenylenediamines

1973 ◽  
Vol 28 (11-12) ◽  
pp. 710-716 ◽  
Author(s):  
Achim Trebst ◽  
Susanne Reimer
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Water Oxidation ◽  
Photosynthetic Electron Transport ◽  
The Other ◽  
Ferricyanide Reduction ◽  
Other Hand ◽  
Transport Chain ◽  
Energy Conserving

Abstract The plastoquinone antagonist dibromothymoquinone interrupts the photosynthetic electron transport chain between photosystem II and I by inhibiting the oxidation of plastohydroquinone by photosystem I. The effect of phenylenediamines on NADP and ferricyanide photoreduction inhibited by dibromothymoquinone is studied in isolated chloroplasts. IV-substituted phenylene­ diamines fully restore NADPH and ATP formation as well as oxygen evolution in DBMIB inhibited NADP reduction, but are practically inactive in stimulating ferricyanide reduction by photo­ system II. On the other hand phenylenediamine and C-substituted phenylenediamines are only weakly active in restoring NADP reduction but are very active in stimulating ferricyanide reduc­ tion. The P/e2 ratio in restoration of NADP reduction by phenylenediamines is close to 1, whereas the P/e2 ratio in ferricyanide reduction is about 0.4 (the ratio is dependent on the DBMIB con­ centration). The reversal of the DBMIB inhibition in NADP reduction by phenylenediamines is attributed to a bypass of the inhibition site: Reduced phenylenediamines are electron donors for photosystem I after and oxidized phenylenediamines are electron acceptors for photosystem II be­ fore the DBMIB inhibition site. To explain the different rates and P/e2 ratios in the various systems it is assumed that all phenylenediamines are reduced at the expense of water oxidation by photo­ system II but via plastoquinone and on the inside of the membrane. Therefore two energy con­ serving steps (i. e. two proton releasing sites on the inside of the membrane) are involved, N-sub­ stituted phenylenediamines like TMPD reduced by photosystem II inside remain inside the mem­ brane and are reoxidized inside by photosystem I. This way they connect photosystem II bade onto photosystem I, electron transport rates are high and the P/e2 ratio is one in the restored NADP photoreduction. Phenylenediamine and C-substituted phenylenediamines on the other hand travel back to the outside through the membrane, and by doing so carry some of the protons released on the inside of the membrane by the energy conserving steps back to the outside. This way they are very active in stimulating the rate of ferricyanide photoreduction but the P/e2 ratio is only about 0.4. These phenylenediamines being removed from the inside are less active in restoring the rate of NADP reduction

Acclimation of winter rye to cold-hardening temperatures results in an increased capacity for photosynthetic electron transport

1985 ◽  
Vol 63 (3) ◽  
pp. 506-511 ◽  
Author(s):  
N. P. A. Huner
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Cold Hardening ◽  
Differential Sensitivity ◽  
Winter Rye ◽  
Light Utilization ◽  
Secale Cereale L ◽  
Superoxide Free Radical

Photosynthetic electron transport and its partial reactions were measured as a function of light intensity and temperature in isolated chloroplasts from cold-hardened and unhardened rye (Secale cereale L. cv. Puma). Chloroplasts from cold-hardened rye plants exhibited light-saturated rates for whole chain electron transport that were about 1.4-fold higher at 25 °C than those observed in chloroplasts from unhardened rye plants. This was correlated with light-saturated rates of electron transport through photosystem I that were 1.6-fold higher in cold-hardened chloroplasts than in unhardened chloroplasts. These results could not be attributed to a differential uncoupling of electron transport, nor to a differential production of a superoxide free radical which would stimulate net O2 consumption. Electron transport through photosystem II of cold-hardened and unhardened chloroplasts exhibited a differential sensitivity to temperature. The ratio of light-saturated rates in cold-hardened chloroplasts to light-saturated rates in unhardened chloroplasts increased from 0.87 to 1.40 when the temperature was decreased from 26 to 4.5 °C. The locus of this differential temperature sensitivity appeared to reside on the O2 evolving side of photosystem II prior to the site of electron donation by diphenylcarbazide. On the basis of the estimates of the number of photons required for half the maximal rates of electron transport, it was concluded that the efficiency of light utilization by photosystem I and II was unaffected by growth temperature. However, the estimated efficiency for light utilization did increase with a decrease in reaction temperature for chloroplasts from both cold-hardened and unhardened ‘Puma’ rye. Thus, it is concluded that growth at cold-hardening temperatures resulted in an increase in the capacity for photosynthetic electron transport, but did not affect the quantum efficiency for this process.

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.

Superoxide-and Ethane-Formation in Subchloroplast Particles: Catalysis by Pyridinium Derivatives

1980 ◽  
Vol 35 (9-10) ◽  
pp. 770-775 ◽  
Author(s):  
E. F. Elstner ◽  
H. P. Fischer ◽  
W. Osswald ◽  
G. Kwiatkowski
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Redox Potentials ◽  
Light Reaction ◽  
Pyridinium Bromide ◽  
Superoxide Formation ◽  
Fatty Acid Peroxidation ◽  
Chlorophyll Bleaching ◽  
Ethane Formation

Abstract Oxygen reduction by chloroplast lamellae is catalyzed by low potential redox dyes with E′0 values between -0 .3 8 V and -0 .6 V. Compounds of E′0 values of -0 .6 7 V and lower are inactive. In subchloroplast particles with an active photosystem I but devoid of photosynthetic electron transport between the two photosystems, the active redox compounds enhance chlorophyll bleaching, superoxide formation and ethane production independent on exogenous substrates or electron donors. The activities of these compounds decrease with decreasing redox potential, with one exception: 1-methyl-4,4′-bipyridini urn bromide with an E′0 value of lower -1 V (and thus no electron acceptor of photosystem I in chloroplast lamellae with intact electron transport) stimulates light dependent superoxide formation and unsaturated fatty acid peroxidation in sub­ chloroplast particles, maximal rates appearing after almost complete chlorophyll bleaching. Since this activity is not visible with compounds with redox potentials below -0 .6 V lacking the nitrogen atom at the 1-position of the pyridinium substituent, we assume that 1 -methyl-4,4′-bi-pyridinium bromide is “activated” by a yet unknown light reaction.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Photoinhibition of Electron Transport Activity of Photosystem II in Isolated Thylakoids Studied by Thermoluminescence and Delayed Luminescence

1988 ◽  
Vol 43 (11-12) ◽  
pp. 871-876 ◽  
Author(s):  
Imre Vass ◽  
Narendranath Mohanty ◽  
Sándor Demeter
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Half Life ◽  
Delayed Luminescence ◽  
Transport Activity ◽  
Primary Target ◽  
Electron Transport Activity ◽  
The Stability ◽  
Spinach Thylakoids

Abstract The effect of photoinhibition on the primary (QA) and secondary (QB) quinone acceptors of photosystem I I was investigated in isolated spinach thylakoids by the methods of thermoluminescence and delayed luminescence. The amplitudes of the Q (at about 2 °C) and B (at about 30 °C) thermoluminescence bands which are associated with the recombination of the S2QA- and S2QB charge pairs, respectively, exhibited parallel decay courses during photoinhibitory treatment. Similarly, the amplitudes of the flash-induced delayed luminescence components ascribed to the recombination of S20A and S2OB charge pairs and having half life-times of about 3 s and 30 s, respectively, declined in parallel with the amplitudes of the corresponding Q and B thermoluminescence bands. The course of inhibition of thermoluminescence and delayed luminescence intensity was parallel with that of the rate of oxygen evolution. The peak positions of the B and Q thermoluminescence bands as well as the half life-times of the corresponding delayed luminescence components were not affected by photoinhibition. These results indicate that in isolated thylakoids neither the amount nor the stability of the reduced OB acceptor is preferentially decreased by photoinhibition. We conclude that either the primary target of photodamage is located before the O b binding site in the reaction center of photosystem II or QA and OB undergo simultaneous damage.

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