scholarly journals Light Quality Affects Chloroplast Electron Transport Rates Estimated from Chl Fluorescence Measurements

2017 ◽  
Vol 58 (10) ◽  
pp. 1652-1660 ◽  
Author(s):  
John R Evans ◽  
Patrick B Morgan ◽  
Susanne von Caemmerer
Keyword(s):  
Electron Transport ◽  
Light Quality ◽  
Fluorescence Measurements ◽  
Electron Transport Rates ◽  
Chl Fluorescence

Determination of Herbicide Inhibition of Photosynthetic Electron Transport by Fluorescence

Weed Science ◽  
1983 ◽  
Vol 31 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Edward P. Richard ◽  
John R. Goss ◽  
Charles J. Arntzen ◽  
Fred W. Slife
Keyword(s):  
Electron Transport ◽  
Foliar Application ◽  
Photosynthetic Electron Transport ◽  
Fluorescence Measurements ◽  
Abaxial Leaf Surface ◽  
Terminal Level ◽  
Non Destructive ◽  
Kinetics Of ◽  
Chl Fluorescence

The kinetics of chlorophyll (Chl) fluorescence was used as a tool for detecting herbicide inhibition in studies using intact soybean [Glycine max(L.) Merr.] leaves. The terminal level of fluorescence (FT), obtained 150 s after the onset of illumination of the abaxial leaf surface, was found to be independent of the dark preadaptation interval and to vary little between leaflets and leaves within and among untreated plants. Increases in FTwere detected in plants following the foliar application of herbicides which inhibit photosynthetic electron transport. Fluorescence measurements indicated significant electron transport inhibition in leaves following treatment with 40-mM solutions of either atrazine [2-chloro-4-(ethylamino)-6-(isopropyiamino)-s-triazine] or diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] after 0.5 and 1 h, respectively. Results of this study indicate that Chl fluorescence can be used to measure injury qualitatively by photosynthetic electron transport-inhibiting herbicides in intact plants long before visual symptoms of injury occur. Possible uses of this sensitive, rapid, and non-destructive technique for studying herbicide penetration as affected by adjuvants and environmental factors are discussed.

Chlorophyll fluorescence evaluation of agrochemical interactions with propanil on propanil-resistant barnyardgrass (Echinochloa crus-galli)

Weed Science ◽  
1999 ◽  
Vol 47 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Jason K. Norsworthy ◽  
Ronald E. Talbert ◽  
Robert E. Hoagland
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Synergistic Effects ◽  
Laboratory Studies ◽  
Photosynthetic Inhibition ◽  
Fluorescence Measurements ◽  
Transport Inhibition ◽  
Leaf Segments

Resistance to propanil by a barnyardgrass (BYG) biotype has been reported, and its occurrence is becoming widespread in U.S. rice-producing regions. Interactions between propanil and the herbicides anilofos, molinate, pendimethalin, piperophos, quinclorac, and thiobencarb and the insecticide carbaryl were evaluated in laboratory studies for improved control of propanil-resistant barnyardgrass (R-BYG). Chlorophyll fluorescence measurements of BYG leaf segments were used to ascertain electron transport inhibition and to assess the synergy/antagonism of propanil (100 μM) with the various additives (50 μM). Synergistic effects on photosynthetic inhibition were found with anilofos, carbaryl, pendimethalin, and piperophos in combination with propanil. Such synergistic actions of chemicals with propanil may lead to chemical combinations useful for R-BYG control.

Resistance to chlortoluron in a downy brome (Bromus tectorum) biotype

Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 237-245 ◽  
Author(s):  
Julio Menendez ◽  
Fernando Bastida ◽  
Rafael de Prado
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Fold Increase ◽  
Downy Brome ◽  
Fresh Weight ◽  
Wheat Field ◽  
P450 Monooxygenases ◽  
Fluorescence Measurements ◽  
Higher Ed ◽  
Herbicide Metabolism

A downy brome population in a winter wheat field at Córdoba, Spain, survived use rates of chlortoluron (2.5 to 3.5 kg ai ha−1) over 2 consecutive yr, where wheat monoculture and multiple annual chlortoluron applications had been carried out. The resistant (CR) biotype showed a higher ED50value (7.4 kg ai ha−1; the concentration required for 50% reduction of fresh weight) than the susceptible (S) control (2.2 kg ai ha−1), with a 3.4-fold increase in chlortoluron tolerance. Chlortoluron resistance in the CR downy brome biotype was not caused by altered absorption, translocation, or modification of the herbicide target site but by enhanced detoxification. The inhibition of both the recovery of photosynthetic electron transport and chlortoluron metabolism in the CR biotype due to the presence of the Cyt P450 inhibitor 1-aminobenzotriazole (ABT) indicates that herbicide metabolism catalyzed by Cyt P450 monooxygenases is related to chlortoluron resistance in CR plants. Although both biotypes degraded chlortoluron byN-dealkylation and ring-methyl hydroxylation and seem to share the same ability to form polar conjugates, degradation in the resistant biotype is more efficacious as this biotype metabolizes the parent herbicide faster and to a greater extent than its susceptible counterpart. The ability of the susceptible biotype to ring-hydroxylate chlortoluron, albeit at much slower rate, probably explains its moderate tolerance to chlortoluron observed in the growth assays and its minor photosynthetic electron transport recovery observed in fluorescence measurements.

scholarly journals Chloroplast Electron Chain, ROS Production, and Redox Homeostasis Are Modulated by COS-OGA Elicitation in Tomato (Solanum lycopersicum) Leaves

2020 ◽  
Vol 11 ◽  
Author(s):  
Sophie Moreau ◽  
Géraldine van Aubel ◽  
Rekin’s Janky ◽  
Pierre Van Cutsem
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Redox Homeostasis ◽  
Crop Protection ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Biomass Accumulation ◽  
Photochemical Quenching ◽  
Fluorescence Measurements ◽  
Transport Chain ◽  
Reduced Nicotinamide Adenine Dinucleotide

The stimulation of plant innate immunity by elicitors is an emerging technique in agriculture that contributes more and more to residue-free crop protection. Here, we used RNA-sequencing to study gene transcription in tomato leaves treated three times with the chitooligosaccharides–oligogalacturonides (COS-OGA) elicitor FytoSave® that induces plants to fend off against biotrophic pathogens. Results showed a clear upregulation of sequences that code for chloroplast proteins of the electron transport chain, especially Photosystem I (PSI) and ferredoxin. Concomitantly, stomatal conductance decreased by half, reduced nicotinamide adenine dinucleotide phosphate [NAD(P)H] content and reactive oxygen species production doubled, but fresh and dry weights were unaffected. Chlorophyll, β-carotene, violaxanthin, and neoxanthin contents decreased consistently upon repeated elicitations. Fluorescence measurements indicated a transient decrease of the effective PSII quantum yield and a non-photochemical quenching increase but only after the first spraying. Taken together, this suggests that plant defense induction by COS-OGA induces a long-term acclimation mechanism and increases the role of the electron transport chain of the chloroplast to supply electrons needed to mount defenses targeted to the apoplast without compromising biomass accumulation.

Kinase-induced changes in electron transport rates of spinach chloroplasts

1982 ◽  
Vol 217 (1) ◽  
pp. 362-367 ◽  
Author(s):  
J.W. Farchaus ◽  
W.R. Widger ◽  
W.A. Cramer ◽  
R.A. Dilley
Keyword(s):  
Electron Transport ◽  
Spinach Chloroplasts ◽  
Electron Transport Rates ◽  
Induced Changes

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.

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