scholarly journals Effect of cobalt on growth, pigments and the photosynthetic electron transport in Monoraphidium minutum and Nitzchia perminuta

2003 ◽  
Vol 15 (3) ◽  
pp. 159-166 ◽  
Author(s):  
M.M. El-Sheekh ◽  
A.H. El-Naggar ◽  
M.E.H. Osman ◽  
E. El-Mazaly
Keyword(s):  
Electron Transport ◽  
Algal Species ◽  
Photosynthetic Electron Transport ◽  
Experimental Period ◽  
Fluorescence Induction ◽  
O2 Evolution ◽  
O2 Uptake ◽  
Acceptor Side ◽  
Low Co2 ◽  
Co2 Concentrations

The unicellular green alga Monoraphidium minutum and the diatom Nitzschia perminuta were cultured under different concentrations of Co2+. Growth and pigment content were slightly increased at low concentrations and inhibited by high Co2+ concentrations. The results concerning the effect of different concentrations of Co2+ on photosynthetic O2 evolution showed a reduction in the amount of O2 evolved by each alga in response to increasing Co2+ concentrations. However, an increase in O2 evolution for both M. minutum and N. perminuta was observed at relatively low Co2+ concentrations. Photosynthetic electron transport in M. minutum was more sensitive to Co2+ toxicity than in N. perminuta. On the other hand, the effect of the heavy metal on respiration showed that higher Co2+ concentrations were inhibitory to O2 uptake by the two algal species. Low Co2+ concentrations stimulated O2 uptake by M. minutum throughout the experimental period. However, in N. perminuta, different concentrations of Co2+ led to a reduction of O2 uptake. To localize the action site of Co2+ in the photosynthetic electron transport chain, the fluorescence induction technique was carried out. According to the results obtained, the inhibitory action of Co2+ is located on the acceptor side of PSII for both M. minutum and N. perminuta.

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.

The Inhibition of Photosynthetic Electron Transport by DBMIB and its Restoration by p-Phenylenediamines; Studied by Means of Prompt and Delayed Chlorophyll Fluorescence of Green Algae

1974 ◽  
Vol 29 (11-12) ◽  
pp. 725-732 ◽  
Author(s):  
Robert Bauer ◽  
Mathijs J. G. Wijnands
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Photosynthetic Electron Transport ◽  
Primary Electron ◽  
Delayed Fluorescence ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Exchange Reactions ◽  
Redox Systems

Abstract The effect of the plastohydroquinone antagonist dibromothym oquinone (DBMIB) on photosynthetic electron transport reactions was studied in the presence and absence of p-phenylene-diamines by means of measurements of prompt and delayed chlorophyll fluorescence induction of the green alga Scenedesm us obliquus. Prompt and delayed chlorophyll fluorescence induction phenomena are valid indicators for the native presence of and cooperation between the two photosynthetic light reactions. Their kinetics reflect the balancing of electron exchange reactions in the chain of coupled redox-systems between the two photosystems upon sudden illumination. From distinct alterations of the short-term (sec) light induced changes in the yield of prom pt and delayed chlorophyll fluorescence it is concluded that DBMIB inhibits the photosynthetic electron transport in the chain of redox-systems between the two light reactions. There is evidence to show that upon illumination of DBMIB treated cells only the reduction of primary electron ac­ceptor pools of photosystem II (i. e. Q and PQ) is still possible. After their reduction the further electron transport through photosystem II is blocked. The addition of p-phenylenediamines to DBM IB-treated cells abolishes the typical DBMIB-affected prom pt and delayed fluorescence inhibition curves and the normal induction curves re­ appear qualitatively in all their important features. From these measurements it is suggested that the redox properties of p-phenylenediamines allow an electron transport bypass of the DBMIB inhibition site which results in a fully restored photosynthetic electron transport from water to NADP.

scholarly journals Response of Photosynthetic Performance to Drought Duration and Re-Watering in Maize

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 533
Author(s):  
Yuying Jia ◽  
Wanxin Xiao ◽  
Yusheng Ye ◽  
Xiaolin Wang ◽  
Xiaoli Liu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Performance ◽  
Electron Acceptors ◽  
Drought Duration ◽  
Acceptor Side ◽  
Antioxidase Activity

The drought tolerance and capacity to recover after drought are important for plant growth and yield. In this study, two maize lines with different drought resistance were used to investigate the effects of different drought durations and subsequent re-watering on photosynthetic capacity, electron transfer and energy distribution, and antioxidative defense mechanisms of maize. Under short drought, maize plants decreased stomatal conductance and photosynthetic electron transport rate, and increased NPQ (Non-photochemical quenching) to dissipate excess excitation energy in time and protect the photosynthetic apparatus. With the increased drought duration, NPQ, antioxidase activity, PItotal (total performance index), ∆I/Io, ψEo (quantum yield for electron transport), φEo (efficiency/probability that an electron moves further than QA−), δRo (efficiency/probability with which an electron from the intersystem electron carriers is transferred to reduce end electron acceptors at the PSI acceptor side) and φRo (the quantum yield for the reduction of the end electron acceptors at the PSI acceptor side) were significantly reduced, while Y(NO) (quantum yield of nonregulated energy dissipation) and MDA (malondialdehyde) began to quickly increase. The photosynthetic rate and capacity of photosynthetic electron transport could not recover to the level of the plants subjected to normal water status after re-watering. These findings indicated that long drought damaged the PSI (photosystem I) and PSII (photosystem II) reaction center and decreased the electron transfer efficiency, and this damage could not be recovered by re-watering. Different drought resistance and recovery levels of photosynthetic performance were achieved by different maize lines. Compared with D340, D1798Z had higher NPQ and antioxidase activity, which was able to maintain functionality for longer in response to progressive drought, and it could also recover at more severe drought after re-watering, which indicated its higher tolerance to drought. It was concluded that the capacity of the energy dissipation and antioxidant enzyme system is crucial to mitigate the effects caused by drought, and the capacity to recover after re-watering was dependent on the severity and persistence of drought, adaptability, and recovery differences of the maize lines. The results provide a profound insight to understand the maize functional traits’ responses to drought stresses and re-watering.

scholarly journals Photosynthetic electron transport in a cell-free preparation from the thermophilic blue-green alga Phormidium laminosum

1980 ◽  
Vol 188 (2) ◽  
pp. 351-361 ◽  
Author(s):  
A C Stewart ◽  
D S Bendall
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
High Potential ◽  
O2 Evolution ◽  
Blue Green Alga ◽  
Phormidium Laminosum ◽  
A Cell ◽  
Membrane Bound

1. A cell-free preparation of membrane fragments was prepared from the thermophilic blue-green alga Phormidium laminosum by lysozyme treatment of the cells followed by osmotic shock to lyse the spheroplasts. The membrane fragments showed high rates of photosynthetic electron transport and O2 evolution (180-250 mumol of O2/h per mg of chlorophyll a with 2,6-dimethyl-1,4-benzoquinone as electron acceptor). O2-evolution activity was stable provided that cations (e.g. 10mM-Mg2+ or 100mM-Na+) or glycerol (25%, v/v) were present in the suspending medium. 2. The components of the electron-transport chain in P. laminosum were similar to those of other blue-green algae: the cells contained Pigment P700, plastocyanin, soluble high-potential cytochrome c-553, soluble low-potential cytochrome c-54 and membrane-bound cytochromes f, b-563 and b-559 (both low- and high-potential forms). The amounts and midpoint potentials of the membrane-bound cytochromes were similar to those in higher-plant chloroplasts. 3. Although O2 evolution in P. laminosum spheroplasts was resistant to high temperatures, thermal stability was not retained in the cell-free preparation. However, in contrast with higher plants, O2 evolution in P. laminosum membrane fragments was remarkably resistant to the non-ionic detergent Triton X-100.

The Leafless Orchid Cymbidium macrorhizon Performs Photosynthesis in the Pericarp during the Fruiting Season

2021 ◽  
Author(s):  
Koichi Kobayashi ◽  
Kenji Suetsugu ◽  
Hajime Wada
Keyword(s):  
Electron Transport ◽  
Mycorrhizal Fungi ◽  
Significant Proportion ◽  
Photochemical Efficiency ◽  
Fluorescence Analysis ◽  
Photosynthetic Electron Transport ◽  
Isotopic Analysis ◽  
Fluorescence Induction ◽  
Induction Kinetics ◽  
Chl Fluorescence

Abstract Photosynthesis with highly photoreactive chlorophyll (Chl) provides energy for plant growth but with simultaneous risk of photooxidative damage and photoprotection costs. Although the leafless orchid Cymbidium macrorhizon mostly depends on mycorrhizal fungi for carbon, it accumulates Chl particularly during fruiting and may not be fully mycoheterotrophic. In fact, stable isotopic analysis suggested that the fruiting C. macrorhizon specimens obtain a significant proportion of its carbon demands through photosynthesis. However, actual photosynthetic characteristics of this leafless orchid are unknown. To reveal the functionality of photosynthetic electron transport in C. macrorhizon, we compared its photosynthetic properties with those of its relative mixotrophic orchid Cymbidium goeringii and the model plant Arabidopsis thaliana. Compared with C. goeringii and A. thaliana, maximum photochemical efficiency of PSII was substantially low in C. macrorhizon. Chl fluorescence induction kinetics revealed that the electron transport capacity of PSII was limited in C. macrorhizon. Chl fluorescence analysis at 77 K suggested partial energetic disconnection of the light-harvesting antenna from the PSII reaction center in C. macrorhizon. Despite its low PSII photochemical efficiency, C. macrorhizon showed photosynthetic electron transport activity both in the field and under laboratory conditions. Cymbidium macrorhizon developed strong nonphotochemical quenching in response to increased light intensity as did C. goeringii, suggesting the functionality of photoprotective systems in this orchid. Moreover, C. macrorhizon fruit developed stomata on the pericarp and showed net O2-evolving activity. Our data demonstrate that C. macrorhizon can perform photosynthetic electron transport in the pericarp, although its contribution to net carbon acquisition may be limited.

Examination of pre-industrial and future [CO2] reveals the temperature-dependent CO2 sensitivity of light energy partitioning at PSII in eucalypts

2010 ◽  
Vol 37 (11) ◽  
pp. 1041 ◽  
Author(s):  
Barry A. Logan ◽  
Carolyn R. Hricko ◽  
James D. Lewis ◽  
Oula Ghannoum ◽  
Nathan G. Phillips ◽  
...  
Keyword(s):  
Electron Transport ◽  
Energy Dissipation ◽  
Fluorescence Emission ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
Energy Partitioning ◽  
O2 Evolution ◽  
Tree Seedlings ◽  
Temperature Dependent ◽  
Photosynthetic O2 Evolution

We grew faster-growing Eucalyptus saligna Sm. and slower-growing Eucalyptus sideroxylon A. Cunn ex Woolls tree seedlings in sunlit glasshouses at all combinations of 290 µL L–1 (pre-industrial), 400 µL L–1 (modern) or 650 µL L–1 (future) global atmospheric CO2 ([CO2]), and ambient or ambient + 4°C temperature. To assess photosynthetic performance, we simultaneously measured light-saturated CO2 assimilation (Asat) and chlorophyll fluorescence emission along with the capacity for photosynthetic O2 evolution and leaf pigment composition. Photosynthetic response to [CO2] was similar between species. Increasing [CO2] but not temperature increased Asat. The response of photosynthetic electron transport to [CO2] was temperature-dependent and manifested through adjustments in energy partitioning at PSII. Increasing [CO2] resulted in greater PSII operating efficiencies at the elevated temperature. We observed no associated acclimatory adjustments in the capacity for photosynthetic O2 evolution or changes in leaf chlorophyll content. Photoprotective energy dissipation responded to increasing [CO2] and temperature. Across species and treatments, increased energy partitioning to electron transport was always associated with decreased partitioning to energy dissipation. Our results suggest that in response to increasing [CO2] and temperature, E. saligna and E. sideroxylon meet increased demands for the products of electron transport via adjustments in energy partitioning, not through acclimation of the capacity for photosynthetic electron transport or light absorption.

Effects of Pyridate on Chickpea

1995 ◽  
Vol 22 (5) ◽  
pp. 731 ◽  
Author(s):  
R Gimeenez-Espinosa ◽  
R Jimenez-Diaz ◽  
RD Prado
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Fluorescence Intensity ◽  
Active Ingredient ◽  
Photosynthetic Activity ◽  
Photosynthetic Electron Transport ◽  
Fluorescence Induction ◽  
Hill Reaction ◽  
Lolium Rigidum ◽  
Cicer Arietinum L

The effects of pyridate on 15 different chickpea (Cicer arietinum L.) genotypes have been investigated under controlled environmental conditions. Different degrees of tolerance to pyridate were detected. Pyridate applied at 2.0 and 4.0 kg active ingredient ha-1 inhibited the growth of two of the 15 genotypes. Chlorophyll fluorescence intensity showed high levels of inhibition 3 h after treatment in chickpea. For all the genotypes, photosynthetic activity was recovered 10 days after treatment. Fluorescence-induction curves revealed that pyridate inhibited photosynthetic electron transport in chickpea genotypes and Amaranthus blitoides faster than in Lolium rigidum. Photosynthesis in chickpea genotypes recovered more quickly than in Lolium rigidum, while Amaranthus blitoides died 3 days after treatment. Hill reaction assays concluded that CL9673 was the most phytotoxic pyridate metabolite. The order of phytotoxicity was CL9673 >> CL9673-N-Gly > CL9869 > pyridate > CL9673-O-Gly. These results support the idea that tolerance of chickpea to pyridate is due to degradation and detoxification of the herbicide.

scholarly journals The effects of oxygen solubility and high concentrations of salts on photosynthetic electron transport in chloroplast membranes

1984 ◽  
Vol 218 (2) ◽  
pp. 539-545 ◽  
Author(s):  
B Thomasset ◽  
J N Barbotin ◽  
D Thomas
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Potassium Citrate ◽  
Potassium Ferricyanide ◽  
O2 Evolution ◽  
Oxygen Solubility ◽  
Chloroplast Membranes ◽  
Ferricyanide Reduction ◽  
High Concentrations ◽  
Stimulation Of

Chloroplast membranes were isolated in different media containing Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid] and high concentrations of sorbitol (0.33 M), potassium citrate (0.75 M) or Na2SO4 (1.0 M). Due to the complexity of the media, the oxygen solubility is strongly modified by high concentrations of salts (oxygen solubility for 0.33 M-sorbitol, 0.21 mmol/litre; for 0.75 M-potassium citrate, 0.121 mmol/litre; and for 1.0 M-Na2SO4, 0.112 mmol/litre). The knowledge of these values is necessary to interpret the rate of O2 evolution. For thylakoids isolated in ‘sorbitol buffer’ and then tested in high concentrations of potassium citrate, a slight stimulation of O2 evolution is observed (143-173 mumol of O2/h per mg of chlorophyll a) with potassium ferricyanide as electron acceptor. When we monitor the potassium ferricyanide reduction, no stimulation of electron transport is obtained even if the observed phenomenon is identical with the Photosystem-II oxygen evolution. In the same experiments no stimulation of the photophosphorylation was recorded, but when thylakoids are directly isolated in 0.75 M-potassium citrate, O2 evolution, ferricyanide reduction and photophosphorylation are inhibited by high concentrations of salts. The behaviour of thylakoids seems to be influenced by their initial treatment.

Picrate Salt of a Cyclic Polyether, 18-Crown-6 (Ca-picrate-18-crown-6), Inhibits the Photosynthetic Electron Transport at the Acceptor Side of Photosystem II

1998 ◽  
Vol 53 (3-4) ◽  
pp. 159-162
Author(s):  
Manoj K. Joshi ◽  
T. S. Desai ◽  
Prasanna Mohanty
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Photosynthetic Electron Transport ◽  
Acceptor Side ◽  
Site Of Action ◽  
Fast Chlorophyll A Fluorescence

Abstract It has been demonstrated that cyclic polyether, K -picrate-18-crown-6 inhibited photosyn­ thetic electron transport (Sabat et al., 1991, Z. Naturforsch. 46c , 87-92) . We further analyzed the alterations induced in the fast chlorophyll a fluorescence and thermoluminescence pattern of pea thylakoids by calcium-18-crown-6 (crown-picrate). The results indicate that the site of action of calcium crown-picrate is at the acceptor side of photosystem II.

scholarly journals Molecular Mechanism of Oxidation of P700 and Suppression of ROS Production in Photosystem I in Response to Electron-Sink Limitations in C3 Plants

Antioxidants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 230 ◽  
Author(s):  
Chikahiro Miyake
Keyword(s):  
Electron Transport ◽  
Molecular Mechanism ◽  
Transport System ◽  
Photosystem I ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Electron Transport System ◽  
C3 Plants ◽  
Ros Production ◽  
Acceptor Side

Photosynthesis fixes CO2 and converts it to sugar, using chemical-energy compounds of both NADPH and ATP, which are produced in the photosynthetic electron transport system. The photosynthetic electron transport system absorbs photon energy to drive electron flow from Photosystem II (PSII) to Photosystem I (PSI). That is, both PSII and PSI are full of electrons. O2 is easily reduced to a superoxide radical (O2−) at the reducing side, i.e., the acceptor side, of PSI, which is the main production site of reactive oxygen species (ROS) in photosynthetic organisms. ROS-dependent inactivation of PSI in vivo has been reported, where the electrons are accumulated at the acceptor side of PSI by artificial treatments: exposure to low temperature and repetitive short-pulse (rSP) illumination treatment, and the accumulated electrons flow to O2, producing ROS. Recently, my group found that the redox state of the reaction center of chlorophyll P700 in PSI regulates the production of ROS: P700 oxidation suppresses the production of O2− and prevents PSI inactivation. This is why P700 in PSI is oxidized upon the exposure of photosynthesis organisms to higher light intensity and/or low CO2 conditions, where photosynthesis efficiency decreases. In this study, I introduce a new molecular mechanism for the oxidation of P700 in PSI and suppression of ROS production from the robust relationship between the light and dark reactions of photosynthesis. The accumulated protons in the lumenal space of the thylakoid membrane and the accumulated electrons in the plastoquinone (PQ) pool drive the rate-determining step of the P700 photo-oxidation reduction cycle in PSI from the photo-excited P700 oxidation to the reduction of the oxidized P700, thereby enhancing P700 oxidation.

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