scholarly journals Surface Canopy Position Determines the Photosystem II Photochemistry in Invasive and Native Prosopis Congeners at Sharjah Desert, UAE

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 740
Author(s):  
M. Iftikhar Hussain ◽  
François Mitterand tsombou ◽  
Ali El-Keblawy
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
United Arab Emirates ◽  
Photochemical Quenching ◽  
Leaf Biomass ◽  
Photosystem Ii Photochemistry ◽  
Canopy Position ◽  
Excess Light ◽  
Arid Desert ◽  
The Impact

Plants have evolved photoprotective mechanisms in order to counteract the damaging effects of excess light in hyper-arid desert environments. We evaluated the impact of surface canopy positions on the photosynthetic adjustments and chlorophyll fluorescence attributes (photosystem II photochemistry, quantum yield, fluorescence quenching, and photon energy dissipation), leaf biomass and nutrient content of sun-exposed leaves at the south east (SE canopy position) and shaded-leaves at the north west (NW canopy position) in the invasive Prosopis juliflora and native Prosopis cineraria in the extreme environment (hyper-arid desert area, United Arab Emirates (UAE)). The main aim of this research was to study the photoprotection mechanism in invasive and native Prosopis congeners via the safe removal—as thermal energy—of excess solar energy absorbed by the light collecting system, which counteracts the formation of reactive oxygen species. Maximum photosynthetic efficiency (Fv/Fm) from dark-adapted leaves in P. juliflora and P. cineraria was higher on NW than SE canopy position while insignificant difference was observed within the two Prosopis congeners. Greater quantum yield was observed in P. juliflora than P. cineraria on the NW canopy position than SE. With the change of canopy positions from NW to SE, the reduction of the PSII reaction center activity in the leaves of both Prosopis congeners was accelerated. On the SE canopy position, a significant decline in the electron transport rate (ETR) of in the leaves of both Prosopis congeners occurred, which might be due to the blockage of electron transfer from QA to QB on the PSII acceptor side. On the SE canopy position; Prosopis leaves dissipated excess light energy by increasing non-photochemical quenching (NPQ). However, in P. cineraria, the protective ability of NPQ decreased, which led to the accumulation of excess excitation energy (1 − qP)/NPQ and the aggravation of photoinhibition. The results also explain the role of different physiological attributes contributing to invasiveness of P. juliflora and to evaluate its liaison between plasticity of these characters and invasiveness.

scholarly journals Temperature-dependent chlorophyll accumulation and photosystem II assembly during etioplast to chloroplast transition in sunflower cotyledons

2017 ◽  
Vol 76 (1) ◽  
pp. 107-110
Author(s):  
Hrvoje Lepeduš ◽  
Mario Jakopec ◽  
Jasenka Antunović Dunić ◽  
Goran Krizmanić ◽  
Sanida Osmanović ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Heat Dissipation ◽  
Higher Plants ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Chlorophyll Accumulation ◽  
Different Temperatures ◽  
The Impact ◽  
Quantum Yield Of Psii

Abstract Despite numerous data dealing with the biogenesis of photosynthetic membranes connected with specific functional alterations in higher plants this is still an insufficiently understood topic and is one of the most promising areas of research in plant biochemistry. The main goal of our study was to detect the impact of different temperatures on chlorophyll biosynthesis and the maximum quantum yield of PSII (Fv/Fm). Therefore, we investigated the greening processes in etiolated sunflower cotyledons (Helianthus annuus L.) grown at different temperatures (10, 20 and 30 °C) during 24 h. The dynamics of chlorophyll a and b (Chl a and Chl b) accumulation as well as photosystem II (PSII) effi ciency were observed. We also evaluated combined effects of different temperatures (20 and 30 °C) and short-term application of increased irradiation (800 μmol m-2 s-1) on effective quantum yield of PSII (ΔF/F’m) and non photochemical quenching (NPQ) in cotyledons with fully developed PSII. Our results showed reduced chlorophyll accumulation and the arrest of PSII assembly at 10 °C in comparison with 20 and 30 °C. Further, the increased irradiance induced equal down regulation of effective quantum yield of PSII at 20 and 30 °C, with significantly higher capability of heat dissipation at 30 °C.

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

1999 ◽  
Vol 26 (3) ◽  
pp. 283 ◽  
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.

Changes in photosynthesis, chlorophyll fluorescence, and antioxidant enzymes of mulberry (Morus ssp.) in response to salinity and high-temperature stress

Biologia ◽  
2013 ◽  
Vol 68 (3) ◽  
Author(s):  
Cui Yu ◽  
Shujun Huang ◽  
Xingming Hu ◽  
Wen Deng ◽  
Chao Xiong ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
High Temperature ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Peroxidase Activity ◽  
High Temperature Stress ◽  
The Other ◽  
Fluorescence Parameters ◽  
Photosystem Ii Photochemistry ◽  
Chl Fluorescence

AbstractPhotosynthesis, chlorophyll (Chl) fluorescence, and antioxidant enzymes were measured in the mulberry (Morus spp.) cultivars Da 10, Hongguo 2, Anza 1, and Taiwan 72C002, which were subjected to salinity and high-temperature stress (STS; 0.1%, 0.3%, and 0.5% NaCl concentrations, 34.5°C–40.5°C/27.8°C–29.2°C day/night temperatures). Control plants were watered with 1 L of full-strength Hoagland’s nutrient solution with no added NaCl. Net photosynthetic rate (P N), stomatal conductance (g s), and effective quantum yield of photosystem II photochemistry (ΦPSII) increased in Anza 1 and Taiwan 72C002 under 0.1% STS but decreased in Da 10 and Hongguo 2 compared with the control. However, all the above parameters, including Chl content, maximum quantum yield of photosystem II photochemistry (Fv/Fm), nonphotochemical quenching (NPQ), and maximum carboxylation velocity of Rubisco (V cmax, decreased in Taiwan 72C002, Honggua 2, and Da 10 under 0.3% and 0.5% STS, suggesting that photoinhibition occurred under severe STS. Under STS, there were no significant changes in P N, Fv/Fm, ΦPSII, ascorbate peroxidase (APX) activity, superoxide dismutase (SOD) activity, catalase activity, superoxide anion radical (O2−) content, malondialdehyde (MDA) content, soluble sugar content (SSC), and leaf biomass in Anza 1 even at 0.5% STS, showing that Anza 1 displays high resistance to STS. In addition, peroxidase activity was significantly higher in Anza 1 than in the other mulberry cultivars. Significant adverse effects of severe salinity on photosynthesis and Chl fluorescence parameters were observed in Da 10. Additionally, SOD, peroxidase, and APX activities were lower in Da 10, whereas O2− and MDA contents were higher in comparison with the other mulberry cultivars under 0.3% and 0.5% STS, suggesting that Da 10 had low resistance to STS. These results show that 0.1% STS had a positive effect on photosynthesis and Chl fluorescence parameters in Anza 1 and Taiwan 72C002, and higher peroxidase activity can to a certain extent explain the higher STS tolerance in Anza 1. Damages to DSM photosystems might be related to lower SOD, POD, and APX activities, which resulted in the accumulation of reactive oxygen species.

scholarly journals Changes in Photo-Protective Energy Dissipation of Photosystem II in Response to Beneficial Bacteria Consortium in Durum Wheat under Drought and Salinity Stresses

2020 ◽  
Vol 10 (15) ◽  
pp. 5031 ◽  
Author(s):  
Mohammad Yaghoubi Khanghahi ◽  
Sabrina Strafella ◽  
Carmine Crecchio
Keyword(s):  
Chlorophyll Fluorescence ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Durum Wheat ◽  
Photochemical Quenching ◽  
Plant Growth Promoting Bacteria ◽  
Psii Photochemistry ◽  
Non Photochemical Quenching

The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy.

scholarly journals Transcriptional regulation of photoprotection in dark-to-light transition - more than just a matter of excess light energy

2021 ◽  
Author(s):  
Petra Redekop ◽  
Emanuel Sanz-Luque ◽  
Yizhong Yuan ◽  
Gaelle Villain ◽  
Dimitris Petroutsos ◽  
...  
Keyword(s):  
Light Intensity ◽  
Photosynthetic Electron Transport ◽  
Time Of Day ◽  
Photochemical Quenching ◽  
Mrna Accumulation ◽  
Photosynthetic Organisms ◽  
Light Spectra ◽  
Excess Light ◽  
Non Photochemical Quenching ◽  
The Impact

In nature, photosynthetic organisms are exposed to different light spectra and intensities depending on the time of day and atmospheric and environmental conditions. When photosynthetic cells absorb excess light, they induce non-photochemical quenching to avoid photo-damage and trigger expression of photoprotective genes. In this work, we used the green alga Chlamydomonas reinhardtii to assess the impact of light intensity, light quality, wavelength, photosynthetic electron transport and CO2 on induction of the photoprotective genes (LHCSR1, LHCSR3 and PSBS) during dark-to-light transitions. Induction (mRNA accumulation) occurred at very low light intensity, was independently modulated by blue and UV-B radiation through specific photoreceptors, and only LHCSR3 was strongly controlled by CO2 levels through a putative enhancer function of CIA5, a transcription factor that controls genes of the carbon concentrating mechanism. We propose a model that integrates inputs of independent signaling pathways and how they may help the cells anticipate diel conditions and survive in a dynamic light environment.

scholarly journals Change in H+ Transport across Thylakoid Membrane as Potential Mechanism of 14.3 Hz Magnetic Field Impact on Photosynthetic Light Reactions in Seedlings of Wheat (Triticum aestivum L.)

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2207
Author(s):  
Ekaterina Sukhova ◽  
Ekaterina Gromova ◽  
Lyubov Yudina ◽  
Anastasiia Kior ◽  
Yana Vetrova ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Photosystem Ii ◽  
Thylakoid Membrane ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Terrestrial Plants ◽  
Short Term ◽  
Low Frequencies ◽  
Resonance Frequencies ◽  
Non Photochemical Quenching

Natural and artificial extremely low-frequency magnetic fields (ELFMFs) are important factors influencing physiological processes in living organisms including terrestrial plants. Earlier, it was experimentally shown that short-term and long-term treatments by ELFMFs with Schumann resonance frequencies (7.8, 14.3, and 20.8 Hz) influenced parameters of photosynthetic light reactions in wheat leaves. The current work is devoted to an analysis of potential ways of this ELFMF influence on the light reactions. Only a short-term wheat treatment by 14.3 Hz ELFMF was used in the analysis. First, it was experimentally shown that ELFMF-induced changes (an increase in the effective quantum yield of photosystem II, a decrease in the non-photochemical quenching of chlorophyll fluorescence, a decrease in time of changes in these parameters, etc.) were observed under the action of ELFMF with widely ranging magnitudes (from 3 to 180 µT). In contrast, the potential quantum yield of photosystem II and time of relaxation of the energy-dependent component of the non-photochemical quenching were not significantly influenced by ELFMF. Second, it was shown that the ELFMF treatment decreased the proton gradient across the thylakoid membrane. In contrast, the H+ conductivity increased under this treatment. Third, an analysis of the simplest mathematical model of an H+ transport across the thylakoid membrane, which was developed in this work, showed that changes in H+ fluxes related to activities of the photosynthetic electron transport chain and the H+-ATP synthase were not likely a mechanism of the ELFMF influence. In contrast, changes induced by an increase in an additional H+ flux (probably, through the proton leakage and/or through the H+/Ca2+ antiporter activity in the thylakoid membrane) were in good accordance with experimental results. Thus, we hypothesized that this increase is the mechanism of the 14.3 Hz ELFMF influence (and, maybe, influences of other low frequencies) on photosynthetic light reactions in wheat.

Quantitative assessment of the high-light tolerance in plants with an impaired photosystem II donor side

2019 ◽  
Vol 476 (9) ◽  
pp. 1377-1386 ◽  
Author(s):  
Sam Wilson ◽  
Alexander V. Ruban
Keyword(s):  
Photosystem Ii ◽  
Redox State ◽  
Photochemical Quenching ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Donor Side ◽  
Acceptor Side ◽  
Oxygen Evolving ◽  
The Impact

Abstract Photoinhibition is the light-induced down-regulation of photosynthetic efficiency, the primary target of which is photosystem II (PSII). Currently, there is no clear consensus on the exact mechanism of this process. However, it is clear that inhibition can occur through limitations on both the acceptor- and donor side of PSII. The former mechanism is caused by electron transport limitations at the PSII acceptor side. Whilst, the latter mechanism relies on the disruption of the oxygen-evolving complex. Both of these mechanisms damage the PSII reaction centre (RC). Using a novel chlorophyll fluorescence methodology, RC photoinactivation can be sensitively measured and quantified alongside photoprotection in vivo. This is achieved through estimation of the redox state of QA, using the parameter of photochemical quenching in the dark (qPd). This study shows that through the use of PSII donor-side inhibitors, such as UV-B and Cd2+, there is a steeper gradient of photoinactivation in the systems with a weakened donor side, independent of the level of NPQ attained. This is coupled with a concomitant decline in the light tolerance of PSII. The native light tolerance is partially restored upon the use of 1,5-diphenylcarbazide (DPC), a PSII electron donor, allowing for the balance between the inhibitory pathways to be sensitively quantified. Thus, this study confirms that the impact of donor-side inhibition can be detected alongside acceptor-side photoinhibition using the qPd parameter and confirms qPd as a valid, sensitive and unambiguous parameter to sensitively quantify the onset of photoinhibition through both acceptor- or donor-side mechanisms.

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