scholarly journals High light alongside elevated PCO2 alleviates thermal depression of photosynthesis in a hard coral (Pocillopora acuta)

2020 ◽  
Vol 223 (20) ◽  
pp. jeb223198
Author(s):  
Robert A. B. Mason ◽  
Christopher B. Wall ◽  
Ross Cunning ◽  
Sophie Dove ◽  
Ruth D. Gates
Keyword(s):  
Elevated Temperature ◽  
Ocean Acidification ◽  
Environmental Changes ◽  
Dark Respiration ◽  
Interactive Effect ◽  
Light Availability ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Photochemical Quenching ◽  
Strong Light

ABSTRACTThe absorbtion of human-emitted CO2 by the oceans (elevated PCO2) is projected to alter the physiological performance of coral reef organisms by perturbing seawater chemistry (i.e. ocean acidification). Simultaneously, greenhouse gas emissions are driving ocean warming and changes in irradiance (through turbidity and cloud cover), which have the potential to influence the effects of ocean acidification on coral reefs. Here, we explored whether physiological impacts of elevated PCO2 on a coral–algal symbiosis (Pocillopora acuta–Symbiodiniaceae) are mediated by light and/or temperature levels. In a 39 day experiment, elevated PCO2 (962 versus 431 µatm PCO2) had an interactive effect with midday light availability (400 versus 800 µmol photons m−2 s−1) and temperature (25 versus 29°C) on areal gross and net photosynthesis, for which a decline at 29°C was ameliorated under simultaneous high-PCO2 and high-light conditions. Light-enhanced dark respiration increased under elevated PCO2 and/or elevated temperature. Symbiont to host cell ratio and chlorophyll a per symbiont increased at elevated temperature, whilst symbiont areal density decreased. The ability of moderately strong light in the presence of elevated PCO2 to alleviate the temperature-induced decrease in photosynthesis suggests that higher substrate availability facilitates a greater ability for photochemical quenching, partially offsetting the impacts of high temperature on the photosynthetic apparatus. Future environmental changes that result in moderate increases in light levels could therefore assist the P. acuta holobiont to cope with the ‘one–two punch’ of rising temperatures in the presence of an acidifying ocean.

Acquired tolerance of the photosynthetic apparatus to photoinhibition as a result of growing Solanum lycopersicum at moderately higher temperature and light intensity

2019 ◽  
Vol 46 (6) ◽  
pp. 555 ◽  
Author(s):  
Milena T. Gerganova ◽  
Aygyun K. Faik ◽  
Maya Y. Velitchkova
Keyword(s):  
High Temperature ◽  
Quantum Yield ◽  
Light Intensity ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Cyclic Electron Flow ◽  
Photochemical Quenching ◽  
Kinetics Of ◽  
Moderately High Temperature

The kinetics of photoinhibition in detached leaves from tomato plants (Solanium lycopersicum L. cv. M82) grown for 6 days under different combinations of optimal and moderately high temperature and optimal and high light intensity were studied. The inhibition of PSII was evaluated by changes in maximal quantum yield, the coefficient of photochemical quenching and the quantum yield of PSII. The changes of PSI activity was estimated by the redox state of P700. The involvement of different possible protective processes was checked by determination of nonphotochemical quenching and cyclic electron flow around PSI. To evaluate to what extent the photosynthetic apparatus and its response to high light treatment was affected by growth conditions, the kinetics of photoinhibition in isolated thylakoid membranes were also studied. The photochemical activities of both photosystems and changes in the energy distribution and interactions between them were evaluated by means of a Clark electrode and 77 K fluorescence analysis. The data showed an increased tolerance to photoinhibition in plants grown under a combination of moderately high temperature and light intensity, which was related to the stimulation of cyclic electron flow, PSI activity and rearrangements of pigment–protein complexes, leading to a decrease in the excitation energy delivered to PSII.

scholarly journals Functional redundancy and crosstalk between flavodiiron proteins and NDH-1 in Synechocystis sp. PCC 6803

2019 ◽  
Author(s):  
Lauri Nikkanen ◽  
Anita Santana Sánchez ◽  
Maria Ermakova ◽  
Matthias Rögner ◽  
Laurent Cournac ◽  
...  
Keyword(s):  
Electron Transport ◽  
Light Availability ◽  
Photosynthetic Apparatus ◽  
Growth Conditions ◽  
Functional Redundancy ◽  
High Light ◽  
Transport Pathway ◽  
Photosynthetic Organisms ◽  
Electron Transport Pathway ◽  
Pcc 6803

ABSTRACTIn oxygenic photosynthetic organisms excluding angiosperms, flavodiiron proteins (FDPs) catalyze light-dependent reduction of O2 to H2O. This alleviates electron pressure on the photosynthetic apparatus and protects it from photodamage. In Synechocystis sp. PCC 6803, four FDP isoforms function as hetero-oligomers of Flv1 and Flv3 and/or Flv2 and Flv4. An alternative electron transport pathway mediated by the NAD(P)H dehydrogenase-like complex (NDH-1) also contributes to redox hemostasis and the photoprotection of photosynthesis. Four NDH-1 types haven been characterized in cyanobacteria: NDH-11 and NDH-12, which function in respiration; and NDH-13 and NDH-14, which function in CO2 uptake. All four types are involved in cyclic electron transport. Along with single FDP mutants (Δflv1 and Δflv3) and the double NDH-1 mutants (Δd1d2, which is deficient in NDH-11,2 and Δd3d4, which is deficient in NDH-13,4), we studied triple mutants lacking either one of Flv1 or Flv3, and NDH-11,2 or NDH-13,4. We show that the presence of either Flv1/3 or NDH-11,2, but not NDH-13,4, is indispensable for survival during changes in growth conditions from high CO2 /moderate light to low CO2 / high light. Our results suggest functional redundancy and crosstalk between FDPs and NDH-11,2 under the studied conditions, and demonstrate that the functions of FDPs and NDH-11,2 are dynamically coordinated for the efficient oxidation of PSI and for photoprotection under variable CO2 and light availability.One sentence summaryFlavodiiron proteins and NDH-1 complex ensure survival of cyanobacterial cells by cooperatively safeguarding the photosynthetic apparatus against excessive reduction

scholarly journals Molecular genetics of xanthophyll–dependent photoprotection in green algae and plants

2000 ◽  
Vol 355 (1402) ◽  
pp. 1385-1394 ◽  
Author(s):  
Irene Baroli ◽  
Krishna K. Niyogi
Keyword(s):  
Reactive Oxygen Species ◽  
Photosynthetic Apparatus ◽  
Reactive Oxygen ◽  
High Light ◽  
Multiple Roles ◽  
Oxygenic Photosynthesis ◽  
Photochemical Quenching ◽  
Oxygen Species ◽  
Non Photochemical Quenching ◽  
Extragenic Suppressors

The involvement of excited and highly reactive intermediates in oxygenic photosynthesis inevitably results in the generation of reactive oxygen species. To protect the photosynthetic apparatus from oxidative damage, xanthophyll pigments are involved in the quenching of excited chlorophyll and reactive oxygen species, namely 1 Chl*, 3 Chl*, and 1 1O 2 *. Quenching of 1 Chl* results in harmless dissipation of excitation energy as heat and is measured as non–photochemical quenching (NPQ) of chlorophyll fluorescence. The multiple roles of xanthophylls in photoprotection are being addressed by characterizing mutants of Chlamydomonas reinhardtii and Arabidopsis thaliana . Analysis of Arabidopsis mutants that are defective in 1 Chl* quenching has shown that, in addition to specific xanthophylls, the psbS gene is necessary for NPQ. Double mutants of Chlamydomonas and Arabidopsis that are deficient in zeaxanthin, lutein and NPQ undergo photo–oxidative bleaching in high light. Extragenic suppressors of the Chlamydomonas npq1 lor1 double mutant identify new mutations that restore varying levels of zeaxanthin accumulation and allow survival in high light.

scholarly journals Photosynthetic Physiology Comparisons between No Tillage and Sod Culture of Citrus Farming in Different Seasons under Various Light Intensities

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1805
Author(s):  
Chung-I. Chen ◽  
Kuan-Hung Lin ◽  
Meng-Yuan Huang ◽  
Chih-Kai Yang ◽  
Yu-Hsiu Lin ◽  
...  
Keyword(s):  
Dark Respiration ◽  
Photosynthetic Apparatus ◽  
Net Photosynthesis ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Light Quantum ◽  
No Tillage ◽  
Photosynthetic Physiology ◽  
Light Intensities ◽  
Different Seasons

Sod culture (SC) and no tillage (NT) are modern orchard management systems, and are two different bases for the sustainable development and production of citrus orchards in Taiwan. However, there is no information about the efficiency of either NT or SC on the photosynthetic physiology of farmed citrus under different seasons and varying light intensities. The objective of this study was to clarify the impacts of SC and NT under eco-friendly farming management on the photosynthetic apparatus of an important plantation citrus species in response to varying light intensities over the seasons. The results showed that Rd (dark respiration rate of CO2), Qy (light quantum yield of CO2), LCP (light compensation point), Amax (maximum net assimilation of CO2), and Fv/Fm values of citrus plants under SC were somewhat higher under NT in the same season, particularly in the fall and in winter. As light intensity increased from 200 to 2000 μmol photon m−2 s−1 PPFD, higher Pn (net photosynthesis rate), Gs (stomatal conductance), ETR (electron transport rate), NPQ (non-photochemical quenching), and Fv/Fm (potential quantum efficiency of PSII) values were observed in spring and summer compared to the fall and winter, and increasing NPQ and decreasing Fv/Fm values were observed in all seasons. Positive and significant correlations were shown between the Pn and Gs under NT and SC in all seasons with all light illuminations, whereas significant and negative relationships were observed between the ETR and NPQ under NT in fall and winter at 1200~2000 PPFD. In short, ETR was useful for non-destructive estimations of Pn and NPQ since these indices were significantly and positively correlated with ETR in citrus leaves exposed to 0~1200 PPFD in all seasons and 1200~2000 PPFD in spring, the fall, and winter, providing a quick means to identify the physiological condition of plants under various seasons and tillages. The precise management of photosynthetic parameters such as ETR in response to light irradiances under varied seasons also provides implications for sustainable citrus production for tillage cropping systems in future higher CO2 and potentially wetter or drier environments. The tillages may hold promise for maximizing the economic efficiency of the growth and development of citrus plants grown in the field.

scholarly journals PHOTOPROTECTIIVE STRATEGIES OF UNICELULAR RED ALGA RHODELLA VIOLACEA DURING ACCLIMATION TO STRONG LIGHT

2020 ◽  
Vol 3 (11(80)) ◽  
pp. 31-38
Author(s):  
K. Neverov
Keyword(s):  
Fluorescence Quenching ◽  
Red Algae ◽  
Molecular Mechanisms ◽  
Light Exposure ◽  
Photosynthetic Apparatus ◽  
Water Soluble ◽  
Photochemical Quenching ◽  
Strong Light ◽  
Rhodella Violacea ◽  
Chl Fluorescence

Red algae contain in their photosynthetic machinery water-soluble antenna complexes - phycobilisomes (PBSs) attached to thylakoid membranes to transfer excitation energy to photosystems. Strong light absorbed by the PBSs triggers a fast formation of transthylakoid ΔpH that follows the non-photochemical quenching of chlorophyll (Chl) fluorescence. The ΔpH build-up seems to be essential for photoprotecting the photosynthetic apparatus in the absence of xanthophyll cycle common to higher plants. However, the photoprotective mechanisms of red algae are not studied in details yet.  We present here our research of the Chl fluorescence quenching in unicellular red algae Rhodella violacea and its correlation with the ΔpH gradient being formed. The relation of this phenomenon to photoprotection of photosystem 2 (PS 2) in the normal and high light-acclimated Rhodella cells is also examined.  Under the photoinhibitory conditions (white light of 2000-3000 μE/m2s), the ΔpH-dependent Chl fluorescence quenching was found to delay the kinetics of PS 2 photoinhibition. The uncouplers like nigericin and NH4Cl are known to break down ΔpH gradient, lead to the dissipation of Chl fluorescence quenching followed by enhancing the PS 2 photoinhibition rate. The same effect showed far-red (FR) light consuming transthylakoid ΔpH. ATPase inhibitor, DCCD, having no impact on ΔpH didn’t influence PS 2 photoinhibition as well this implies the photoprotection to be fulfilled by the proton gradient rather than by ATP synthesis.  Long-term acclimation of Rhodella cells to higher irradiances (500-1000 μE/m2s) results in a partial loss of the periphery phycoerythrin-containing subunits by PBSs. The light-acclimated cultures display a higher resistance to the photoinhibitory light than the non-acclimated ones. This could be explained by diminishing the energy transfer from the reduced PBSs to PS 2 as well as light screening by the secondary carotenoids synthesized during light exposure.  Data on low-temperature (77K) fluorescence allow to evaluate the molecular mechanisms of light-induced Chl fluorescence suppression in Rhodella cells and its recovery in darkness. 

LHC-like proteins involved in stress responses and biogenesis/repair of the photosynthetic apparatus

2019 ◽  
Vol 476 (3) ◽  
pp. 581-593 ◽  
Author(s):  
Jean-David Rochaix ◽  
Roberto Bassi
Keyword(s):  
Stress Responses ◽  
Photosynthetic Apparatus ◽  
Chlorophyll Synthesis ◽  
Photochemical Reactions ◽  
High Light ◽  
Protein Family ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Small Proteins

AbstractLHC (light-harvesting complex) proteins of plants and algae are known to be involved both in collecting light energy for driving the primary photochemical reactions of photosynthesis and in photoprotection when the absorbed light energy exceeds the capacity of the photosynthetic apparatus. These proteins usually contain three transmembrane (TM) helices which span the thylakoid membranes and bind several chlorophyll, carotenoid and lipid molecules. In addition, the LHC protein family includes LHC-like proteins containing one, two, three or even four TM domains. One-helix proteins are not only present in eukaryotic photosynthetic organisms but also in cyanobacteria where they have been named high light-inducible proteins. These small proteins are probably the ancestors of the members of the extant LHC protein family which arouse through gene duplications, deletions and fusions. During evolution, some of these proteins have diverged and acquired novel functions. In most cases, LHC-like proteins are induced in response to various stress conditions including high light, high salinity, elevated temperature and nutrient limitation. Many of these proteins play key roles in photoprotection, notably in non-photochemical quenching of absorbed light energy. Moreover, some of these proteins appear to be involved in the regulation of chlorophyll synthesis and in the assembly and repair of Photosystem II and also of Photosystem I possibly by mediating the insertion of newly synthesized pigments into the photosynthetic reaction centers.

scholarly journals Differential Physiological Responses of Small Thalassiosira pseudonana and Large Thalassiosira punctigera to the Shifted-High Light and Nitrogen

2021 ◽  
Vol 9 (5) ◽  
pp. 450
Author(s):  
Zhen Qin ◽  
Xiaomin Xia ◽  
Guangming Mai ◽  
Yehui Tan ◽  
Gang Li
Keyword(s):  
Environmental Changes ◽  
Dark Respiration ◽  
High Light ◽  
Thalassiosira Pseudonana ◽  
Utilization Efficiency ◽  
Extreme Weather Events ◽  
Growth Responses ◽  
Limited Effect ◽  
Sod Activity ◽  
Weather Events

With global warming, the intensity and frequency of extreme episodic weather events such as typhoons are rising in tropical and subtropical regions, disturbing the water column and shifting phytoplankton therein from deep to surface layers, and exposing them to high light as well as nutrients. To explore how phytoplankton respond to such environmental changes, we tracked the growth, cell compositions and physiology of small Thalassiosira pseudonana and large Thalassiosira punctigera from simulated ambient to upward-shifted light and nitrogen (N) conditions. Shifting to high levels of light caused a limited effect on the growth of small T. pseudonana, but reduced that of large T. punctigera by 36%, with supplemental N alleviating the light-caused growth reduction. The upward-shifted light reduced the cellular pigments contents in small T. pseudonana, but not in large T. punctigera. The upward-shifted light reduced the photosynthetic capability (FV/FM) of both species, as well as the light utilization efficiency (α) and maximal relative electron transport rate (rETRmax), but it enhanced their dark reparations. Moreover, the upward-shifted light did not affect the superoxide dismutase (SOD) activity of small T. pseudonana, but it did enhance that of large T. punctigera. In addition, the supplemental N showed a limited effect on cellular pigments and the dark respiration of T. pseudonana, but it reduced that of T. punctigera. Our results showed that the growth responses of Thalassiosira to upward-shifted light and nitrogen vary with species and possibly with cell size, indicating that the field species composition might change after the occurrence of extreme weather events.

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

Light Absorption and Partitioning in Response to Nitrogen in Apple Leaves

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541a-541
Author(s):  
Lailiang Cheng ◽  
Leslie H. Fuchigami ◽  
Patrick J. Breen
Keyword(s):  
High Light ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Light Conditions ◽  
Psii Efficiency ◽  
Fluorescence Measurements ◽  
Free Radical Formation ◽  
Highly Correlated ◽  
Non Photochemical Quenching ◽  
Leaf N

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.

scholarly journals Heatwave frequency and seedling death alter stress-specific emissions of volatile organic compounds in Aleppo pine

Oecologia ◽  
2021 ◽  
Author(s):  
Benjamin Birami ◽  
Ines Bamberger ◽  
Andrea Ghirardo ◽  
Rüdiger Grote ◽  
Almut Arneth ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Gas Exchange ◽  
Organic Compounds ◽  
Stress Responses ◽  
Methyl Salicylate ◽  
Environmental Changes ◽  
Pinus Halepensis ◽  
Dark Respiration ◽  
Seedling Mortality ◽  
Volatile Organic

AbstractBiogenic volatile organic compounds (BVOC) play important roles in plant stress responses and can serve as stress indicators. While the impacts of gradual environmental changes on BVOCs have been studied extensively, insights in emission responses to repeated stress and recovery are widely absent. Therefore, we studied the dynamics of shoot gas exchange and BVOC emissions in Pinus halepensis seedlings during an induced moderate drought, two four-day-long heatwaves, and the combination of drought and heatwaves. We found clear stress-specific responses of BVOC emissions. Reductions in acetone emissions with declining soil water content and transpiration stood out as a clear drought indicator. All other measured BVOC emissions responded exponentially to rising temperatures during heat stress (maximum of 43 °C), but monoterpenes and methyl salicylate showed a reduced temperature sensitivity during the second heatwave. We found that these decreases in monoterpene emissions between heatwaves were not reflected by similar declines in their internal storage pools. Because stress intensity was extremely severe, most of the seedlings in the heat-drought treatment died at the end of the second heatwave (dark respiration ceased). Interestingly, BVOC emissions (methanol, monoterpenes, methyl salicylate, and acetaldehyde) differed between dying and surviving seedlings, already well before indications of a reduced vitality became visible in gas exchange dynamics. In summary, we could clearly show that the dynamics of BVOC emissions are sensitive to stress type, stress frequency, and stress severity. Moreover, we found indications that stress-induced seedling mortality was preceded by altered methanol, monoterpene, and acetaldehyde emission dynamics.

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