On the relationship between the quantum yield of Photosystem II electron transport, as determined by chlorophyll fluorescence and the quantum yield of CO2-dependent O2 evolution

The quantum yields of non-cyclic electron transport from photosystem II (determined from chlorophyll a fluorescence) and carbon dioxide assimilation were measured in vivo in representative species of the three subgroups of C4 plants (NADP-malic enzyme, NAD-malic enzyme and PEP-carboxykinase) over a series of intercellular CO2 concentrations (CI) at both 21% and 2% O2. The CO2 assimilation rate was independent of O2 concentration over the entire range of Ci (up to 500 μbar) in all three C4 subgroups. The quantum yield of PS II electron transport was similar, or only slightly greater, in 21% v. 2% O2 at all Ci values. In contrast, in the C3 species wheat there was a large O2 dependent increase in PS II quantum yield at low CO2, which reflects a high level of photorespiration. In the C4 plants, the relationship of the quantum yield of PS II electron transport to the quantum yield of CO2 fixation is linear suggesting that photochemical use of energy absorbed by PS II is tightly linked to CO2 fixation in C4 plants. This relationship is nearly identical in all three subgroups and may allow estimates of photosynthetic rates of C4 plants based on measurements of PS II photochemical efficiency. The results suggest that in C4 plants both the photoreduction of O2 and photorespiration are low, even at very limiting CO2 concentrations.

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The function of D1-H332 in Photosystem II electron transport studied by thermoluminescence and chlorophyll fluorescence in site-directed mutants of Synechocystis 6803

European Journal of Biochemistry ◽

10.1111/j.0014-2956.2004.04287.x ◽

2004 ◽

Vol 271 (17) ◽

pp. 3523-3532 ◽

Cited By ~ 35

Author(s):

Yagut Allahverdiyeva ◽

Zsuzsanna Deák ◽

András Szilárd ◽

Bruce A. Diner ◽

Peter J. Nixon ◽

...

Keyword(s):

Chlorophyll Fluorescence ◽

Electron Transport ◽

Photosystem Ii ◽

Synechocystis 6803

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Kinetic response of photosystem II photochemistry in the cyanobacterium Spirulina platensis to high salinity is characterized by two distinct phases

Functional Plant Biology ◽

10.1071/pp98119 ◽

1999 ◽

Vol 26 (3) ◽

pp. 283 ◽

Cited By ~ 17

Author(s):

Congming Lu ◽

Giuseppe Torzillo ◽

Avigad Vonshak

Keyword(s):

Electron Transport ◽

Quantum Yield ◽

Photosystem Ii ◽

Spirulina Platensis ◽

High Salinity ◽

Photochemical Quenching ◽

Second Phase ◽

Ps Ii ◽

Reaction Centres ◽

Two Phases

The kinetic response of photosystem II (PS II) photochemistry in Spirulina platensis(Norstedt M2 ) to high salinity (0.75 M NaCl) was found to consist of two phases. The first phase, which was independent of light, was characterized by a rapid decrease (15–50%) in the maximal efficiency of PS II photochemistry (Fv /Fm), the efficiency of excitation energy capture by open PS II reaction centres (Fv′/Fm′), photochemical quenching (qp) and the quantum yield of PS II electron transport (Φ PS II) in the first 15 min, followed by a recovery up to about 80–92% of their initial levels within the next 2 h. The second phase took place after 4 h, in which further decline in above parameters occurred. Such a decline occurred only when the cells were incubated in the light, reaching levels as low as 45–70% of their initial levels after 12 h. At the same time, non-photochemical quenching (qN) and Q B -non-reducing PS II reaction centres increased significantly in the first 15 min and then recovered to the initial level during the first phase but increased again in the light in the second phase. The changes in the probability of electron transfer beyond QA (ψo) and the yield of electron transport beyond QA (φ Eo), the absorption flux (ABS/RC) and the trapping flux (TRo /RC) per PS II reaction centre also displayed two different phases. The causes responsible for the decreased quantum yield of PS II electron transport during the two phases are discussed.

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Changes of Photosystem II Electron Transport in the Chlorophyll-deficient Oilseed Rape Mutant Studied by Chlorophyll Fluorescence and Thermoluminescence

Journal of Integrative Plant Biology ◽

10.1111/j.1744-7909.2007.00441.x ◽

2007 ◽

Vol 49 (5) ◽

pp. 698-705 ◽

Cited By ~ 6

Author(s):

Jun-Wei Guo ◽

Jin-Kui Guo ◽

Yun Zhao ◽

Lin-Fang Du

Keyword(s):

Chlorophyll Fluorescence ◽

Electron Transport ◽

Photosystem Ii ◽

Oilseed Rape

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Protective Effects of Selenium on Wheat Seedlings under Salt Stress

Agronomy ◽

10.3390/agronomy9060272 ◽

2019 ◽

Vol 9 (6) ◽

pp. 272 ◽

Cited By ~ 1

Author(s):

Chiu-Yueh Lan ◽

Kuan-Hung Lin ◽

Wen-Dar Huang ◽

Chang-Chang Chen

Keyword(s):

Salt Stress ◽

Chlorophyll Fluorescence ◽

Energy Dissipation ◽

Quantum Yield ◽

Photosystem Ii ◽

Physiological Traits ◽

Effective Quantum Yield ◽

Enzymatic Antioxidants ◽

Wheat Seedlings ◽

Chlorophyll Fluorescence Parameters

Wheat is a staple food worldwide, but its productivity is reduced by salt stress. In this study, the mitigative effects of 22 μM selenium (Se) on seedlings of the wheat (Triticum aestivum L.) cultivar Taichung SEL. 2 were investigated under different salt stress levels (0, 100, 200, 300, and 400 mM NaCl). Results of the antioxidative capacity showed that catalase (CAT) activity, non-enzymatic antioxidants (total phenols, total flavonoids, and anthocyanins), 1,1-Diphenyl-2-Picryl-Hydrazyl (DPPH) radical-scavenging activity, and the reducing power of Se-treated seedlings were enhanced under saline conditions. The more-stabilized chlorophyll fluorescence parameters (maximal quantum yield of photosystem II (Fv/Fm), minimal chlorophyll fluorescence (F0), effective quantum yield of photosystem II (ΦPSII), quantum yield of regulated energy dissipation of photosystem II (Y(NPQ)), and quantum yield of non-regulated energy dissipation of photosystem II (Y(NO)) and the less-extensive degradation of photosynthetic pigments (total chlorophyll and carotenoids) in Se-treated seedlings were also observed under salt stress. The elongation of shoots and roots of Se-treated seedling was also preserved under salt stress. Protection of these physiological traits in Se-treated seedlings might have contributed to stable growth observed under salt stress. The present study showed the protective effect of Se on the growth and physiological traits of wheat seedlings under salt stress.

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