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.

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.

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.

X-Ray Structure Analysis of a Cyanoacrylate Inhibitor of Photosystem II Electron Transport

1991 ◽  
Vol 46 (1-2) ◽  
pp. 93-98 ◽  
Author(s):  
Helen G. McFadden ◽  
Donald C. Craig ◽  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll Concentration ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Ps Ii ◽  
X Ray ◽  
High Affinity ◽  
Modelling Studies ◽  
Intramolecular Hydrogen

Abstract X-ray crystallographic data for the highly potent cyanoacrylate photosynthetic electron transport inhibitor, (Z)-ethoxyethyl 3-(4-chlorobenzylamino)-2-cyano-4-methylpent-2-enoate, are presented. This compound has a particularly high affinity for the photosystem II (PS II) herbicide receptor with a p I50 value of 9.5 (in the Hill reaction under uncoupled condi­tions with a chlorophyll concentration of 0.1 μg/ml). Data regarding the structure of small li­gands, such as this potent cyanoacrylate, which bind to the site with high affinity may be used to provide the basis for modelling studies of PS II/herbicide complexes. The X-ray data presented confirm the Z-stereochemistry of active cyanoacrylates and demonstrate the pres­ence of a planar core stabilized by an intramolecular hydrogen bond between the ester car­bonyl oxygen and a benzylamino hydrogen atom. In order to assess the importance of the benzylamino -NH -group in this type of cyanoacrylate, analogues containing a methylene group in its place were synthesized and found to be 100-and 1000-fold less active as Hill inhibitors.

Photoautotrophic Cultured Plant Cells: A Novel System to Survey New Photosynthetic Electron Transport Inhibitors

1991 ◽  
Vol 46 (7-8) ◽  
pp. 563-568 ◽  
Author(s):  
Fumihiko Sato ◽  
Yasuyuki Yamada ◽  
Sang Soo Kwak ◽  
Katsunori Ichinose ◽  
Mitsuhiro Kishida ◽  
...  
Keyword(s):  
Electron Transport ◽  
Cultured Cells ◽  
Plant Cells ◽  
Photosynthetic Electron Transport ◽  
Herbicidal Activity ◽  
Marchantia Polymorpha ◽  
Hill Reaction ◽  
Transport Inhibitors ◽  
Comparison Of The Results ◽  
The Hill

Abstract The responses of photoautotrophic (PA) cultured cells of tobacco (Nicotiana tabacum cv. Samsun NN) and liverwort (Marchantia polymorpha L.) to thirty-eight cyclohexanedione derivatives were surveyed. Each derivative was also tested for inhibitory activity on photosynthetic electron transport (PET), using isolated thylakoids, and herbicidal activity, using seed­ lings and mature plants. Comparison of the results from the different assays showed that the responses of PA cells to each com pound correlated more closely with the responses of seed­ lings and mature plants than did the results of the Hill reaction assays. Our findings suggest that PA cultured cells would be a suitable screening material for identifying potential herbicides with PET-inhibiting activity.

Counteraction of Paraquat Toxicity at the Chloroplast Level

1987 ◽  
Vol 42 (7-8) ◽  
pp. 824-828 ◽  
Author(s):  
Brad L. Upham ◽  
Kriton K. Hatzios
Keyword(s):  
Electron Transport ◽  
Pisum Sativum ◽  
Photosynthetic Electron Transport ◽  
Heme Iron ◽  
Hill Reaction ◽  
Ion Toxicity ◽  
Plastoquinone Pool ◽  
Pisum Sativum L ◽  
Paraquat Toxicity ◽  
Isolated Chloroplasts

Six pyridyl derivatives [benzylviologen, 2-anilinopyridine, 1,2-bis(4-pyridyl)ethane, 1,2-bis(4- pyridyl)ethylene, 2-benzoylpyridine, and 2-benzylaminopyridine] and five heme-iron derivatives [hemoglobin, hemin, hematin, ferritin, and ferrocene] were screened for their potential to coun- teract paraquat (1,1′-dimethyl-4.4′-bipyridinium ion) toxicity on pea (Pisum sativum L.) isolated chloroplasts. The H2O -> methylviologen(MV)/O2 and H2O → ferredoxin(Fd)/NADP+ were two Hill reactions assayed with these compounds. Antagonists of paraquat toxicity should inhibit the first Hill reaction but not the latter. All pyridyl derivatives examined did not inhibit the reaction H2O → MV/O2. Ferritin and ferrocene were also ineffective as inhibitors of this reaction. Hemoglobin inhibited the reaction H2O → MV/O2 without inhibiting the reaction H2O → Fd/NADP+, providing protection to pea chloroplasts against paraquat. Hemin and hematin inhibited both Hill reactions examined. They also inhibited H2O → diaminodurene(DAD)ox and durohydro-quinone → MV/O2 Hill reactions but not the dichlorophenol indophenolred → MV/O2 and DADred → MV/O2 Hill reactions. These results suggest that hemin and hematin are inhibiting the photosynthetic electron transport in the plastoquinone-pool region.

scholarly journals Irradiance and nutrient-dependent effects on photosynthetic electron transport in Arctic phytoplankton: A comparison of two chlorophyll fluorescence-based approaches to derive primary photochemistry

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0256410
Author(s):  
Yayla Sezginer ◽  
David J. Suggett ◽  
Robert W. Izett ◽  
Philippe D. Tortell
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Electron Transport Rate ◽  
Photochemical Efficiency ◽  
Photosynthetic Electron Transport ◽  
Marine Phytoplankton ◽  
Transport Rate ◽  
Variable Fluorescence ◽  
Primary Photochemistry ◽  
Electron Transport Rates

We employed Fast Repetition Rate fluorometry for high-resolution mapping of marine phytoplankton photophysiology and primary photochemistry in the Lancaster Sound and Barrow Strait regions of the Canadian Arctic Archipelago in the summer of 2019. Continuous ship-board analysis of chlorophyll a variable fluorescence demonstrated relatively low photochemical efficiency over most of the cruise-track, with the exception of localized regions within Barrow Strait, where there was increased vertical mixing and proximity to land-based nutrient sources. Along the full transect, we observed strong non-photochemical quenching of chlorophyll fluorescence, with relaxation times longer than the 5-minute period used for dark acclimation. Such long-term quenching effects complicate continuous underway acquisition of fluorescence amplitude-based estimates of photosynthetic electron transport rates, which rely on dark acclimation of samples. As an alternative, we employed a new algorithm to derive electron transport rates based on analysis of fluorescence relaxation kinetics, which does not require dark acclimation. Direct comparison of kinetics- and amplitude-based electron transport rate measurements demonstrated that kinetic-based estimates were, on average, 2-fold higher than amplitude-based values. The magnitude of decoupling between the two electron transport rate estimates increased in association with photophysiological diagnostics of nutrient stress. Discrepancies between electron transport rate estimates likely resulted from the use of different photophysiological parameters to derive the kinetics- and amplitude-based algorithms, and choice of numerical model used to fit variable fluorescence curves and analyze fluorescence kinetics under actinic light. Our results highlight environmental and methodological influences on fluorescence-based photochemistry estimates, and prompt discussion of best-practices for future underway fluorescence-based efforts to monitor phytoplankton photosynthesis.

Inhibitory Effects of the Insecticides Allethrin, Lindane, and Jacutin-Fogetten Sublimate on Photosynthetic Electron Transport

1979 ◽  
Vol 34 (11) ◽  
pp. 1070-1071
Author(s):  
Aloysius Wild
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Inhibitory Effects

Abstract The inhibitory effects of the insecticides Allethrin, Lindane, and Jacutin-Fogetten sublimate on photosynthetic electron transport of broken chloroplasts were tested. 50 μmol l-1 Allethrin caused an inhibition of 80% of the benzoquinone and ferricyanide Hill-reactions. 39 μmol l-1 Lindane inhibited the basal, coupled and uncoupled electron transport to ferricyanide up to 35%. The precipitate formed by the sublimation of Jauctin-Fogetten containing Lindane depressed electron transport much more than pure Lindane. 50 μg ml-1 of the sublimate led to an 80% inhibition of ferricyanide Hill-reaction.

Investigations on a Galvanic Cell Driven by Photosynthetic Electron Transport

1978 ◽  
Vol 33 (5-6) ◽  
pp. 392-401 ◽  
Author(s):  
Wolfgang Haehnel ◽  
Adelheid Heupel ◽  
Dorothea Hengstermann
Keyword(s):  
Electron Transport ◽  
Open Circuit Potential ◽  
Photosynthetic Activity ◽  
Photosynthetic Electron Transport ◽  
Open Circuit ◽  
Galvanic Cell ◽  
Platinum Electrodes ◽  
High Effectiveness ◽  
Electron Carriers ◽  
Isolated Chloroplasts

Abstract A light-driven galvanic cell was constructed making use of the photosynthetic activity of isolated chloroplasts. Artificial mediators managed the transfer of electrons from the endogenous electron carriers to the platinum electrodes in each of the joined half-cells. In one the mediators were reduced by electrons originating from water. In the other the mediators were oxidized by photosystem I in the presence of an autoxidizable electron acceptor. The redox potential in the single half-cells has been studied as a function of the lipophilicity of the mediators and their concentration. Further­ more different autoxidizable acceptors and different treatments of the chloroplasts were investigated. The combined half-cells were separated by an ultrafiltration membrane. Upon illumination the system gave rise to an open circuit potential of up to 220 mV. This battery was charged with rates as high as photosynthetic electron transport rates. The results are discussed with respect to the arrangement of the cell and the properties of the components for high effectiveness and maximal potential differences.

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