Assessment of photoprotection mechanisms of grapevines at low temperature

2003 ◽  
Vol 30 (6) ◽  
pp. 631 ◽  
Author(s):  
Luke Hendrickson ◽  
Marilyn C. Ball ◽  
C. Barry Osmond ◽  
Robert T. Furbank ◽  
Wah Soon Chow
Keyword(s):  
Electron Transport ◽  
Low Temperature ◽  
Quantum Efficiency ◽  
Electron Flow ◽  
Strong Dependence ◽  
Photochemical Quenching ◽  
Vitis Vinifera L ◽  
Mehler Reaction ◽  
Sustained Reduction ◽  
Quantum Efficiency Of Psii

The photosynthetic response of grapevine leaves (Vitis vinifera L. cv. Riesling) to low temperature was studied in the field and laboratory. Light-saturated rates of photosynthetic electron transport were lower and non-photochemical energy dissipation was higher when leaves were subject to low morning temperatures than to high afternoon temperatures under field conditions. These responses to low temperatures occurred without sustained reduction of quantum efficiency of PSII as measured by the variable to maximum chlorophyll fluorescence yield ratio, Fv/Fm, after dark adaptation. The temperature dependence of light-saturated apparent electron transport rate, gas exchange and non-photochemical quenching (NPQ) was also examined in laboratory experiments with glasshouse-grown material. NPQ reached saturation at lower light intensity with decreasing temperature. The relationship between the quantum efficiency of PSII and CO2 fixation at 25°C (2–21% O2) and 10°C (2–21% O2) indicated a decreased dependence of electron transport on both photorespiration and the Mehler reaction at the lower temperature. The calculated percentage of electron flow to the Mehler reaction declined faster than photorespiration at low temperature. Warm- and cold-treated leaf discs under saturating light showed very little photoinhibition as measured by sustained reduction in Fv/Fm, which was linearly related to the percentage of functional PSII reaction centres. However, the addition of dithiothreitol greatly enhanced the rate of photoinhibition, indicating a potentially strong dependence on xanthophyll de-epoxidation for photoprotection at low temperature.

scholarly journals Photosynthesis Regulation in Response to Fluctuating Light in the Secondary Endosymbiont Alga Nannochloropsis gaditana

2019 ◽  
Vol 61 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Alessandra Bellan ◽  
Francesca Bucci ◽  
Giorgio Perin ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Incident Light ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Nannochloropsis Gaditana ◽  
Fluctuating Light ◽  
Light Fluctuations

Abstract In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging because they drive oversaturation of photosynthesis with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (non-photochemical quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution, and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. Nannochloropsis gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of the ineffective regulation of electron transport in this species. The role of NPQ, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

Different strategies of acclimation of photosynthesis, electron transport and antioxidative activity in leaves of two cotton species to water deficit

2016 ◽  
Vol 43 (5) ◽  
pp. 448 ◽  
Author(s):  
Xiao-Ping Yi ◽  
Ya-Li Zhang ◽  
He-Sheng Yao ◽  
Hong-Hai Luo ◽  
Ling Gou ◽  
...  
Keyword(s):  
Electron Transport ◽  
Water Deficit ◽  
Heat Dissipation ◽  
Photosynthetic Apparatus ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Antioxidant Systems ◽  
Mehler Reaction ◽  
Cotton Species ◽  
Excess Light

To better understand the adaptation mechanisms of the photosynthetic apparatus of cotton plants to water deficit conditions, the influence of water deficit on photosynthesis, chlorophyll a fluorescence and the activities of antioxidant systems were determined simultaneously in Gossypium hirsutum L. cv. Xinluzao 45 (upland cotton) and Gossypium barbadense L. cv. Xinhai 21 (pima cotton). Water deficit decreased photosynthesis in both cotton species, but did not decrease chlorophyll content or induce any sustained photoinhibition in either cotton species. Water deficit increased ETR/4 − AG, where ETR/4 estimates the linear photosynthetic electron flux and AG is the gross rate of carbon assimilation. The increase in ETR/4 − AG, which represents an increase in photorespiration and alternative electron fluxes, was particularly pronounced in Xinluzao 45. In Xinluzao 45, water deficit increased the activities of antioxidative enzymes, as well as the contents of reactive oxygen species (ROS), which are related to the Mehler reaction. In contrast, moderate water deficit particularly increased non-photochemical quenching (NPQ) in Xinhai 21. Our results suggest that Xinluzao 45 relied on enhanced electron transport such as photorespiration and the Mehler reaction to dissipate excess light energy under mild and moderate water deficit. Xinhai 21 used enhanced photorespiration for light energy utilisation under mild water deficit but, when subjected to moderate water deficit, possessed a high capacity for dissipating excess light energy via heat dissipation.

scholarly journals Efficient Heat Dissipation and Cyclic Electron Flow Confer Daily Air Exposure Tolerance in the Intertidal Seagrass Halophila beccarii Asch

2020 ◽  
Vol 11 ◽  
Author(s):  
Yang Fang ◽  
Zhijian Jiang ◽  
Chunyu Zhao ◽  
Linglan Li ◽  
Chanaka Isuranga Premarathne Maha Ranvilage ◽  
...  
Keyword(s):  
Electron Transport ◽  
Heat Dissipation ◽  
Electron Flow ◽  
Photochemical Quenching ◽  
Linear Electron ◽  
Carbon Utilization ◽  
Mesophyll Cells ◽  
Air Exposure ◽  
Ps Ii ◽  
Intertidal Seagrass

Seagrasses inhabiting the intertidal zone experience periodically repeated cycles of air exposure and rehydration. However, little is known about the photoprotective mechanisms in photosystem (PS)II and PSI, as well as changes in carbon utilization upon air exposure. The photoprotective processes upon air exposure in Halophila beccarii Asch., an endangered seagrass species, were examined using the Dual-PAM-100 and non-invasive micro-test technology. The results showed that air exposure enhanced non-photochemical quenching (NPQ) in both PSII and PSI, with a maximum increase in NPQ and Y(ND) (which represents the fraction of overall P700 that is oxidized in a given state) of 23 and 57%, respectively, resulting in intensive thermal energy dissipation of excess optical energy. Moreover, cyclic electron transport driven by PSI (CEF) was upregulated, reflected by a 50 and 22% increase in CEF and maximum electron transport rate in PSI to compensate for the abolished linear electron transport with significant decreases in pmfLEF (the proton motive force [pmf]) attributable solely to proton translocation by linear electron flow [LEF]). Additionally, H+ fluxes in mesophyll cells decreased steadily with increased air exposure time, exhibiting a maximum decrease of six-fold, indicating air exposure modified carbon utilization by decreasing the proton pump influxes. These findings indicate that efficient heat dissipation and CEF confer daily air exposure tolerance to the intertidal seagrass H. beccarii and provide new insights into the photoprotective mechanisms of intertidal seagrasses. This study also helps explain the extensive distribution of H. beccarii in intertidal zones.

scholarly journals Dynamic Changes in Protein-Membrane Association for Regulating Photosynthetic Electron Transport

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1216
Author(s):  
Marine Messant ◽  
Anja Krieger-Liszkay ◽  
Ginga Shimakawa
Keyword(s):  
Electron Transport ◽  
Thylakoid Membrane ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Damage Repair ◽  
Photosynthetic Organism

Photosynthesis has to work efficiently in contrasting environments such as in shade and full sun. Rapid changes in light intensity and over-reduction of the photosynthetic electron transport chain cause production of reactive oxygen species, which can potentially damage the photosynthetic apparatus. Thus, to avoid such damage, photosynthetic electron transport is regulated on many levels, including light absorption in antenna, electron transfer reactions in the reaction centers, and consumption of ATP and NADPH in different metabolic pathways. Many regulatory mechanisms involve the movement of protein-pigment complexes within the thylakoid membrane. Furthermore, a certain number of chloroplast proteins exist in different oligomerization states, which temporally associate to the thylakoid membrane and modulate their activity. This review starts by giving a short overview of the lipid composition of the chloroplast membranes, followed by describing supercomplex formation in cyclic electron flow. Protein movements involved in the various mechanisms of non-photochemical quenching, including thermal dissipation, state transitions and the photosystem II damage–repair cycle are detailed. We highlight the importance of changes in the oligomerization state of VIPP and of the plastid terminal oxidase PTOX and discuss the factors that may be responsible for these changes. Photosynthesis-related protein movements and organization states of certain proteins all play a role in acclimation of the photosynthetic organism to the environment.

Variations in Chlorophyll Fluorescence Yields in Phytoplankton in the World Oceans

1995 ◽  
Vol 22 (2) ◽  
pp. 341 ◽  
Author(s):  
PG Falkowski ◽  
Z Kolber
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Quantum Efficiency ◽  
Large Scale ◽  
Global Ocean ◽  
Quantum Yields ◽  
Photochemical Quenching ◽  
Basin Scale

The ocean is optically thin and lends itself to large-scale measurements of in vivo chlorophyll fluorescence. In the open ocean, however, phytoplankton chlorophyll concentrations average only 0.2 μg L-1, and hence high sensitivity is required for precise measurements of the fluorescence yields. Over the past decade, we have developed two approaches to achieve the required sensitivity; these are the pump- and probe-technique and a fast repetition rate (FRR) method. Both methods have been adapted for in situ studies and are used to rapidly measure the maximum change in the quantum yield (Δ�max) of photosystem II (PSII), as well as the effective absorption cross-section of PSII (σPSII). Sections of variable fluorescence across the Pacific and Atlantic Oceans reveal the influence of geophysical processes in controlling the quantum yields of phytoplankton photosynthesis. Areas of upwelling, such as off the coast of north-westem Africa, have Fv/Fm values of 0.65, which are close to the maximum achievable values in nutrient-replete cultures. Throughout most of the nutrient-deficient central ocean basins, this quantum efficiency is reduced by more than 50%. In high-nutrient, low- chlorophyll regions of the eastern Equatorial Pacific, the deliberate, large-scale addition of nanomolar iron directly to the ocean leads to a rapid increase in quantum efficiency of the natural phytoplankton community, thereby revealing that in these regions phytoplankton photosynthetic energy conversion efficiency is iron limited. Diel patterns of variation in the upper ocean display midday, intensity- dependent reductions in both upsII and A�max. We interpret the former as indicative of non- photochemical quenching in the antenna, while the latter is a consequence of both rapidly reversible and slowly reversible damage to reaction centres. From knowledge of the incident spectral irradiance, Δ�max, σPSII, and photochemical quenching, the absolute photosynthetic electron transport rate can be derived in real-time. Using unattended, moored continuous measurements of in vivo fluorescence parameters, the derived in situ electron transport rates can be related to satellite observations of the global ocean with basin-scale, seasonal estimates of phytoplankton carbon fixation. Thus, unlike any other photosynthetic parameter, chlorophyll fluorescence can be used to bridge the scales of biophysical responses to ecosystem dynamics.

scholarly journals The Responses of Light Reaction of Photosynthesis to Dynamic Sunflecks in a Typically Shade-Tolerant Species Panax notoginseng

2021 ◽  
Vol 12 ◽  
Author(s):  
Jin-Yan Zhang ◽  
Qiang-Hao Zhang ◽  
Sheng-Pu Shuang ◽  
Zhu Cun ◽  
Hong-Min Wu ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Heat Dissipation ◽  
Electron Flow ◽  
Panax Notoginseng ◽  
High Light ◽  
Low Light ◽  
Light Reaction ◽  
Tolerant Species ◽  
Shade Tolerant Species ◽  
Quantum Efficiency Of Psii

Light is highly heterogeneous in natural conditions, and plants need to evolve a series of strategies to acclimate the dynamic light since it is immobile. The present study aimed to elucidate the response of light reaction of photosynthesis to dynamic sunflecks in a shade-tolerant species Panax notoginseng and to examine the regulatory mechanisms involved in an adaptation to the simulated sunflecks. When P. notoginseng was exposed to the simulated sunflecks, non-photochemical quenching (NPQ) increased rapidly to the maximum value. Moreover, in response to the simulated sunflecks, there was a rapid increase in light-dependent heat dissipation quantum efficiency of photosystem II (PSII) (ΦNPQ), while the maximum quantum yield of PSII under light (Fv′/Fm′) declined. The relatively high fluorescence and constitutive heat dissipation quantum efficiency of PSII (Φf,d) in the plants exposed to transient high light (400, 800, and 1,600 μmol m–2 s–1) was accompanied by the low effective photochemical quantum yield of PSII (ΦPSII) after the dark recovery for 15 min, whereas the plants exposed to transient low light (50 μmol m–2 s–1) has been shown to lead to significant elevation in ΦPSII after darkness recovery. Furthermore, PSII fluorescence and constitutive heat dissipation electron transfer rate (Jf,d) was increased with the intensity of the simulated sunflecks, the residual absorbed energy used for the non-net carboxylative processes (JNC) was decreased when the response of electron transfer rate of NPQ pathway of PSII (JNPQ) to transient low light is restricted. In addition, the acceptor-side limitation of PSI [Y(NA)] was increased, while the donor-side limitation of photosystems I (PSI) [Y(ND)] was decreased at transient high light conditions accompanied with active cyclic electron flow (CEF). Meanwhile, when the leaves were exposed to transient high light, the xanthophyll cycle (V cycle) was activated and subsequently, the JNPQ began to increase. The de-epoxidation state [(Z + A)/(V + A + Z)] was strongly correlated with NPQ in response to the sunflecks. In the present study, a rapid engagement of lutein epoxide (Lx) after the low intensity of sunfleck together with the lower NPQ contributed to an elevation in the maximum photochemical quantum efficiency of PSII under the light. The analysis based on the correlation between the CEF and electron flow devoted to Ribulose-1, 5-bisphosphate (RuBP) oxygenation (JO) indicated that at a high light intensity of sunflecks, the electron flow largely devoted to RuBP oxygenation would contribute to the operation of the CEF. Overall, photorespiration plays an important role in regulating the CEF of the shade-tolerant species, such as P. notoginseng in response to transient high light, whereas active Lx cycle together with the decelerated NPQ may be an effective mechanism of elevating the maximum photochemical quantum efficiency of PSII under light exposure to transient low light.

scholarly journals Low-temperature-processed metal oxide electron transport layers for efficient planar perovskite solar cells

Rare Metals ◽  
2021 ◽  
Author(s):  
Jia-Xing Song ◽  
Xin-Xing Yin ◽  
Zai-Fang Li ◽  
Yao-Wen Li
Keyword(s):  
Solar Cells ◽  
Electron Transport ◽  
Low Temperature ◽  
Metal Oxide ◽  
Low Cost ◽  
Perovskite Solar Cells ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Future Research ◽  
Low Temperature Preparation

Abstract As a promising photovoltaic technology, perovskite solar cells (pero-SCs) have developed rapidly over the past few years and the highest power conversion efficiency is beyond 25%. Nowadays, the planar structure is universally popular in pero-SCs due to the simple processing technology and low-temperature preparation. Electron transport layer (ETL) is verified to play a vital role in the device performance of planar pero-SCs. Particularly, the metal oxide (MO) ETL with low-cost, superb versatility, and excellent optoelectronic properties has been widely studied. This review mainly focuses on recent developments in the use of low-temperature-processed MO ETLs for planar pero-SCs. The optical and electronic properties of widely used MO materials of TiO2, ZnO, and SnO2, as well as the optimizations of these MO ETLs are briefly introduced. The commonly used methods for depositing MO ETLs are also discussed. Then, the applications of different MO ETLs on pero-SCs are reviewed. Finally, the challenge and future research of MO-based ETLs toward practical application of efficient planar pero-SCs are proposed. Graphical abstract

scholarly journals Dip coated SnO2 film as electron transport layer for low temperature processed planar perovskite solar cells

2021 ◽  
Vol 4 ◽  
pp. 100066
Author(s):  
A. Ashina ◽  
Ramya Krishna Battula ◽  
Easwaramoorthi Ramasamy ◽  
Narendra Chundi ◽  
S. Sakthivel ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Transport ◽  
Low Temperature ◽  
Perovskite Solar Cells ◽  
Sno2 Film ◽  
Transport Layer ◽  
Electron Transport Layer

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.

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