The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence

1989 ◽  
Vol 990 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Bernard Genty ◽  
Jean-Marie Briantais ◽  
Neil R. Baker
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Quantum Yield ◽  
Photosynthetic Electron Transport ◽  
The Relationship

The quantum yield of photosynthetic electron transport evaluated by chlorophyll fluorescence as an indicator of drought tolerance in durum wheat

1995 ◽  
Vol 125 (3) ◽  
pp. 325-329 ◽  
Author(s):  
Z. Flagella ◽  
D. Pastore ◽  
R. G. Campanile ◽  
N. Di Fonzo
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Quantum Yield ◽  
Drought Tolerance ◽  
Durum Wheat ◽  
Photosynthetic Electron Transport ◽  
Fluorescence Measurement ◽  
Chlorophyll Fluorescence Parameters ◽  
Percentage Decrease ◽  
Induction Curve

SUMMARYThe chlorophyll fluorescence parameters ΔF/Fm′ and Fv′/Fm′, related respectively to the quantum yield of photosynthetic electron transport and to the efficiency of excitation capture by the open centres of photosystem II, have been evaluated as possible indicators of drought tolerance in durum wheat. ΔF/Fm′ and Fv′/Fm′ measurements were carried out on excised leaves, both control and dehydrated, of 25 cultivars. ΔF/Fm′ and Fv′/Fm′ values were obtained at two times after the start of fluorescence measurement: at 14 s, i.e. during the induction curve (ΔF/Fm′14s and Fv′/Fm′14s) and at 200s, i.e. at steady state fluorescence (ΔF/Fm′200s and Fv′/Fm′200s).In dehydrated leaves a mean significant decrease of 20% (P < 0·001) was observed in ΔF/Fm′14s values. In contrast, no great differences were observed between control and dehydrated leaves with regard to ΔF/Fm′200s, Fv′/Fm′14s and Fv′/Fm′200s.The percentage decrease of ΔF/Fm′14s after dehydration was correlated with the drought susceptibility index (DSI) of the cultivars, evaluated on a yield basis and a significant correlation (r = 0·72, P < 0·001) was found.

Oxygen-sensitive Differences in the Relationship between Photosynthetic Electron Transport and CO2 Assimilation in C3 and C4 Plants during State Transitions

1997 ◽  
Vol 24 (4) ◽  
pp. 495 ◽  
Author(s):  
James R. Andrews ◽  
Neil R. Baker
Keyword(s):  
Electron Transport ◽  
Quantum Efficiency ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
State Transitions ◽  
Large Decrease ◽  
Maize Leaves ◽  
Significant Change ◽  
The Relationship ◽  
State 1

Wheat (C3) and maize (C4) leaves were exposed to light treatments that were limiting for CO2 assimilation and which excite preferentially photosystem I (PSI) or photosystem II (PSII) and induce State 1 or State 2, respectively. In order to examine the relationships between linear electron transport and CO2 in leaves during State transitions, simultaneous measurements of CO2 assimilation, chlorophyll fluorescence and absorbance at 820 nm were used to estimate the quantum efficiencies of CO2 assimilation and PSII and PSI photochemistry. In wheat leaves with photorespiratory activity, no significant change in quantum efficiency of CO2assimilation was observed during State transitions. This was not the case when photorespiration was inhibited with either 2% O2 or 1000 ppm CO2 and transition from State 2 to State 1 was accompanied by a large decrease (c. 20%) in the quantum efficiency of CO2 assimilation which was not associated with a decrease in the quantum efficiency of electron transport through PSII. Photorespiration appears to buffer the quantum efficiency of CO2 assimilation from changes associated with decreases in the rate of CO2 fixation resulting from imbalances in PPFD absorption by PSI and PSII. When maize leaves were subjected to similar State transitions, no significant change in the quantum efficiency of CO2 assimilation was observed on transition from State 2 to State 1, but on switching back to State 2 a very large decrease (c. 40%) was observed. This decrease could be prevented if leaves were maintained in either 2% O2 or 593 ppm CO2. The possible occurrence of photorespiration in maize leaves on transition from State 1 to State 2, which could result from an inhibition of the CO2 concentrating mechanism, cannot account for the decrease in the quantum efficiency of CO2 assimilation since the relationship between PSII electron transport and CO2 assimilation remained similar throughout the State transitions. Also changes in the phosphorylation status of the light-harvesting chlorophyll a/b protein associated with PSII cannot be implicated in this phenomenon.

scholarly journals Chlorophyll fluorescence response of wheat to exogenous application of growth regulators under terminal drought stress

2015 ◽  
Vol 70 (1) ◽  
pp. 13
Author(s):  
Hamid Mohammadi ◽  
Mohsen Janmohammadi ◽  
Naser Sabaghnia
Keyword(s):  
Chlorophyll Fluorescence ◽  
Drought Stress ◽  
Electron Transport ◽  
Quantum Yield ◽  
Photochemical Quenching ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Exogenous Application ◽  
Terminal Drought ◽  
Terminal Drought Stress

<p>Drought stress negatively affects plant photosynthesis and disturbs the electron transport activity. Evaluation of the chlorophyll fluorescence parameters might reflect influence of the environmental stress on plants and can be applied as an indicator of the primary photochemistry of photosynthesis. In current study the effect of foliar application of benzylaminopurine (BAP, a synthetic cytokinin) and abscisic acid (ABA) on chlorophyll fluorescence parameters of relatively drought tolerant (Pishtaz) and susceptible (Karaj3) bread wheat genotypes under well watered and terminal water deficit condition have been evaluated. Terminal drought was induced by withholding water at anthesis stage (Zadoks scale 65). Results showed that coefficient of non-photochemical quenching of variable fluorescence (qN), quantum yield of PS II photochemistry (ΦPSII) and photochemical quenching (qP) were affected by hormone spray treatments. So that evaluation of parameters at 7 day after foliar treatments revealed that ABA significantly increased electron transport rate (ETR) and qN while considerably decreased ΦPSII, gs and maximum quantum yield of photosystem II (Fv/Fm). However exogenous application of cytokinin could increase gs, Fv/Fm and ΦPSII and the highest value of these parameters was recorded in <em>cytokinin </em>treated plants of Pishtaze cv. under well watered condition. Nevertheless, evaluation of the parameters in different periods after spraying showed that with approaching the maturity stage some traits like as gs, Fv/Fm and ETR significantly decreased in both genotypes. Evaluation of gs and Chlorophyll fluorescence parameters of genotypes between different irrigation levels showed that although cv. Pishtaz showed higher performance of PSII under well watered condition, it failed to maintain its superiority under stress condition. This finding suggests that some more responsive parameter like gs, Fv/Fm and ΦPSII can be considered as reliable indicator for understanding the biochemical and physiological effects of exogenous application of phytohormones under terminal drought stress.</p>

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.

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.

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