Photomorphogenesis in the Picocyanobacterium Cyanobium gracile Includes Increased Phycobilisome Abundance Under Blue Light, Phycobilisome Decoupling Under Near Far-Red Light, and Wavelength-Specific Photoprotective Strategies

Photomorphogenesis is a process by which photosynthetic organisms perceive external light parameters, including light quality (color), and adjust cellular metabolism, growth rates and other parameters, in order to survive in a changing light environment. In this study we comprehensively explored the light color acclimation of Cyanobium gracile, a common cyanobacterium in turbid freshwater shallow lakes, using nine different monochromatic growth lights covering the whole visible spectrum from 435 to 687 nm. According to incident light wavelength, C. gracile cells performed great plasticity in terms of pigment composition, antenna size, and photosystem stoichiometry, to optimize their photosynthetic performance and to redox poise their intersystem electron transport chain. In spite of such compensatory strategies, C. gracile, like other cyanobacteria, uses blue and near far-red light less efficiently than orange or red light, which involves moderate growth rates, reduced cell volumes and lower electron transport rates. Unfavorable light conditions, where neither chlorophyll nor phycobilisomes absorb light sufficiently, are compensated by an enhanced antenna size. Increasing the wavelength of the growth light is accompanied by increasing photosystem II to photosystem I ratios, which involve better light utilization in the red spectral region. This is surprisingly accompanied by a partial excitonic antenna decoupling, which was the highest in the cells grown under 687 nm light. So far, a similar phenomenon is known to be induced only by strong light; here we demonstrate that under certain physiological conditions such decoupling is also possible to be induced by weak light. This suggests that suboptimal photosynthetic performance of the near far-red light grown C. gracile cells is due to a solid redox- and/or signal-imbalance, which leads to the activation of this short-term light acclimation process. Using a variety of photo-biophysical methods, we also demonstrate that under blue wavelengths, excessive light is quenched through orange carotenoid protein mediated non-photochemical quenching, whereas under orange/red wavelengths state transitions are involved in photoprotection.

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

Plant and Cell Physiology ◽

10.1093/pcp/pcz174 ◽

2019 ◽

Vol 61 (1) ◽

pp. 41-52 ◽

Cited By ~ 3

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.

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Far-Red Light Accelerates Photosynthesis in the Low-Light Phases of Fluctuating Light

Plant and Cell Physiology ◽

10.1093/pcp/pcz191 ◽

2019 ◽

Vol 61 (1) ◽

pp. 192-202 ◽

Cited By ~ 6

Author(s):

Masaru Kono ◽

Hikaru Kawaguchi ◽

Naoki Mizusawa ◽

Wataru Yamori ◽

Yoshihiro Suzuki ◽

...

Keyword(s):

Red Light ◽

Atp Synthesis ◽

Co2 Assimilation ◽

Photosynthetic Performance ◽

Antenna System ◽

Photochemical Quenching ◽

Low Light ◽

Yield Increase ◽

Fluctuating Light ◽

Psii Photochemistry

Abstract It is well known that far-red light (FR; >700 nm) drives PSI photochemistry, but its effect on photosynthetic performance has received little attention. In this study, the effects of the addition of FR to red fluctuating light (FL) have on photosynthesis were examined in the leaves of Arabidopsis thaliana. Light-activated leaves were illuminated with FL [alternating high light/low light (HL/LL) at 800/30 μmol m−2 s−1] for 10–15 min without or with FR at intensities that reflected natural conditions. The CO2 assimilation rates upon the transition from HL to LL were significantly greater with FR than without FR. The enhancement of photosynthesis by FR was small under the steady-state conditions and in the HL phases of FL. Proton conductivity through the thylakoid membrane (gH+) in the LL phases of FL, estimated from the dark relaxation kinetics of the electrochromic absorbance shift, was greater with FR than without FR. The relaxation of non-photochemical quenching (NPQ) in the PSII antenna system and the increase in PSII photochemistry in the LL phases accelerated in the presence of FR. Similar FR-effects in FL were confirmed in typical sun and shade plants. On the basis of these results, we concluded that FR exerted beneficial effects on photosynthesis in FL by exciting PSI and accelerating NPQ relaxation and PSII-yield increase. This was probably because of the increased gH+, which would reflect faster ΔpH dissipation and ATP synthesis.

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On the origin of a slowly reversible fluorescence decay component in the Arabidopsis npq4 mutant

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2013.0221 ◽

2014 ◽

Vol 369 (1640) ◽

pp. 20130221 ◽

Cited By ~ 39

Author(s):

Luca Dall'Osto ◽

Stefano Cazzaniga ◽

Masamitsu Wada ◽

Roberto Bassi

Keyword(s):

Red Light ◽

Photosynthetic Apparatus ◽

Atp Synthesis ◽

Carotenoid Biosynthesis ◽

Fluorescence Decay ◽

Photon Absorption ◽

State Transitions ◽

Photochemical Quenching ◽

Decay Component ◽

Kinetics Of

Over-excitation of photosynthetic apparatus causing photoinhibition is counteracted by non-photochemical quenching (NPQ) of chlorophyll fluorescence, dissipating excess absorbed energy into heat. The PsbS protein plays a key role in this process, thus making the PsbS-less npq4 mutant unable to carry out qE, the major and most rapid component of NPQ. It was proposed that npq4 does perform qE-type quenching, although at lower rate than WT Arabidopsis . Here, we investigated the kinetics of NPQ in PsbS-depleted mutants of Arabidopsis . We show that red light was less effective than white light in decreasing maximal fluorescence in npq4 mutants. Also, the kinetics of fluorescence dark recovery included a decay component, qM, exhibiting the same amplitude and half-life in both WT and npq4 mutants. This component was uncoupler-sensitive and unaffected by photosystem II repair or mitochondrial ATP synthesis inhibitors. Targeted reverse genetic analysis showed that traits affecting composition of the photosynthetic apparatus, carotenoid biosynthesis and state transitions did not affect qM. This was depleted in the npq4phot2 mutant which is impaired in chloroplast photorelocation, implying that fluorescence decay, previously described as a quenching component in npq4 is, in fact, the result of decreased photon absorption caused by chloroplast relocation rather than a change in the activity of quenching reactions.

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Effectiveness of Light-Quality and Dark-White Growth Light Shifts in Short-Term Light Acclimation of Photosynthesis in Arabidopsis

Frontiers in Plant Science ◽

10.3389/fpls.2021.615253 ◽

2022 ◽

Vol 12 ◽

Author(s):

Elisabeth Hommel ◽

Monique Liebers ◽

Sascha Offermann ◽

Thomas Pfannschmidt

Keyword(s):

Light Quality ◽

Photosynthetic Performance ◽

Light Acclimation ◽

Photosynthetic Acclimation ◽

State Transitions ◽

Photochemical Quenching ◽

Dark Light ◽

Light Shifts ◽

Set Up ◽

Photosynthetic Antenna

Photosynthesis needs to run efficiently under permanently changing illumination. To achieve this, highly dynamic acclimation processes optimize photosynthetic performance under a variety of rapidly changing light conditions. Such acclimation responses are acting by a complex interplay of reversible molecular changes in the photosynthetic antenna or photosystem assemblies which dissipate excess energy and balance uneven excitation between the two photosystems. This includes a number of non-photochemical quenching processes including state transitions and photosystem II remodeling. In the laboratory such processes are typically studied by selective illumination set-ups. Two set-ups known to be effective in a highly similar manner are (i) light quality shifts (inducing a preferential excitation of one photosystem over the other) or (ii) dark-light shifts (inducing a general off-on switch of the light harvesting machinery). Both set-ups result in similar effects on the plastoquinone redox state, but their equivalence in induction of photosynthetic acclimation responses remained still open. Here, we present a comparative study in which dark-light and light-quality shifts were applied to samples of the same growth batches of plants. Both illumination set-ups caused comparable effects on the phosphorylation of LHCII complexes and, hence, on the performance of state transitions, but generated different effects on the degree of state transitions and the formation of PSII super-complexes. The two light set-ups, thus, are not fully equivalent in their physiological effectiveness potentially leading to different conclusions in mechanistic models of photosynthetic acclimation. Studies on the regulation of photosynthetic light acclimation, therefore, requires to regard the respective illumination test set-up as a critical parameter that needs to be considered in the discussion of mechanistic and regulatory aspects in this subject.

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Bicarbonate utilization and pH polarity. The response of photosynthetic electron transport to carbon limitation in Potamogeton lucens leaves

Canadian Journal of Botany ◽

10.1139/b98-078 ◽

1998 ◽

Vol 76 (6) ◽

pp. 1018-1024

Author(s):

Lucina C van Ginkel ◽

Hidde BA Prins

Keyword(s):

Electron Transport ◽

Carbon Source ◽

Chlorophyll A ◽

Redox Regulation ◽

Photosynthetic Electron Transport ◽

High Light ◽

State Transitions ◽

Photochemical Quenching ◽

Carbon Limitation ◽

Bicarbonate Utilization

By the process of pH polarity, several submersed angiosperms can use bicarbonate as carbon source for photosynthesis. Under conditions of relatively high light intensity and low CO2 availability, the pH of the apoplast and unstirred layer becomes acid at one side of the leaf and alkaline at the other. In the acid region, bicarbonate is converted into CO2, which diffuses into the leaf where it is fixed. Previous experiments on the light-dependent reduction of extracellular electron acceptors led to the hypothesis of redox regulation. Under conditions of high light and low CO2, excess reducing power in the chloroplast was supposed to be shuttled to the cytoplasm where it can upregulate the plasma membrane proton pump, leading to activation of polarity. Chlorophyll a fluorescence is an indicator for photosynthetic electron transport, the energization of thylakoids, and the reoxidation of chloroplast NADPH. It was used therefore to test redox regulation in vivo in Potamogeton lucens L. leaves. The fluoresence parameter, qP, an indicator for photochemical quenching and NADPH reoxidation, appeared to be rather insensitive to the inorganic carbon concentration and to the presence or absence of polarity. In contrast, qN, an indicator for non-photochemical quenching related to thylakoid energization, photoinhibition, and state transitions, increased under conditions of low CO2 - high light and polarity. Taken together the data show polarity to be an effective mechanism to make bicarbonate accessible as carbon source and seem to agree with the idea of redox regulation of pH polarity.Key words: bicarbonate utilization, chlorophyll a fluoresence, pH polarity, redox regulation, Potamogeton lucens, submerged aquatic macrophyte.

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

Cells ◽

10.3390/cells10051216 ◽

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.

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Providing an additional electron sink by the introduction of cyanobacterial flavodiirons enhances the growth of Arabidopsis thaliana in varying light

10.1101/2020.02.05.935346 ◽

2020 ◽

Cited By ~ 1

Author(s):

Suresh Tula ◽

Fahimeh Shahinnia ◽

Michael Melzer ◽

Twan Rutten ◽

Rodrigo Gómez ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Electron Transport ◽

Photosystem I ◽

Photosynthetic Electron Transport ◽

Photosynthetic Performance ◽

Growth Potential ◽

Photochemical Quenching ◽

Transport Chain ◽

Non Photochemical Quenching ◽

Electron Sink

AbstractThe ability of plants to maintain photosynthesis in a dynamically changing environment is of central importance for their growth. As their photosynthetic machinery typically cannot adapt rapidly to fluctuations in the intensity of radiation, the level of photosynthetic efficiency is not always optimal. Cyanobacteria, algae, non-vascular plants (mosses and liverworts) and gymnosperms all produce flavodiirons (Flvs), a class of proteins not represented in the angiosperms; these proteins act to mitigate the photoinhibition of photosystem I. Here, genes specifying two cyanobacterial Flvs have been expressed in the chloroplasts of Arabidopsis thaliana in an attempt to improve the robustness of Photosystem I (PSI). The expression of Flv1 and Flv3 together shown to enhance the efficiency of the utilization of light and to boost the plant’s capacity to accumulate biomass. Based on an assessment of the chlorophyll fluorescence in the transgenic plants, the implication was that photosynthetic activity (including electron transport flow and non-photochemical quenching during a dark-to-light transition) was initiated earlier in the transgenic than in wild type plants. The improved photosynthetic performance of the transgenics was accompanied by an increased production of ATP, an acceleration of carbohydrate metabolism and a more pronounced partitioning of sucrose into starch. The indications are that Flvs are able to establish an efficient electron sink downstream of PSI, thereby ensuring that the photosynthetic electron transport chain remains in a more oxidized state. The expression of Flvs in a plant acts to both protect photosynthesis and to control the ATP/NADPH ratio; together, their presence is beneficial for the plant’s growth potential.

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Silver nanoparticles affect germination and photosynthesis in tobacco seedlings

Acta Botanica Croatica ◽

10.37427/botcro-2020-029 ◽

2020 ◽

Vol 80 (1) ◽

Author(s):

Renata Biba ◽

Mirta Tkalec ◽

Petra Cvjetko ◽

Petra Peharec Štefanić ◽

Sandra Šikić ◽

...

Keyword(s):

Silver Nanoparticles ◽

Electron Transport ◽

Root Growth ◽

Germination Rate ◽

Photosynthetic Performance ◽

Photochemical Quenching ◽

Chemical Transformations ◽

Fresh Weight ◽

Relative Electron ◽

Tobacco Seedlings

Extensive commercialization of silver nanoparticles (AgNPs) raises the risk of their accumulation in the soil-plant system. Once released into the environment, AgNPs are prone to chemical transformations, which makes it hard to determine whether their phytotoxic effects are purely NP-related or a consequence of released Ag+ ions. In this study the effects of 25, 50, 75, 100 and 150 μM AgNPs and AgNO3 on seed germination and early growth of tobacco (Nicotiana tabacum L.) seedlings were compared. Additionally, the effect on photosynthetic performance and pigment content were investigated. Germination rate and index values indicated delayed and slower germination in some AgNP treatments. Lower AgNP concentrations stimulated root growth, but induced prominent reduction in fresh weight. Contrary, all AgNO3 concentrations inhibited root growth but only the higher ones decreased fresh weight. Obtained results imply that the observed AgNP toxicity could be ascribed to NP form and can be correlated with high AgNP stability in the solid medium. On the other hand, majority of AgNP and AgNO3 treatments induced an increase in chlorophyll content which was accompanied with significantly lower values of relative electron transport rate and coefficient of photochemical quenching, implying an inhibition of the electron transport chain. Similar impact of AgNPs and AgNO3 on photosynthesis can be correlated with lower stability of AgNPs in the liquid medium, resulting in AgNP aggregation and dissolution of Ag+ ions.

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Macroorganisation and flexibility of thylakoid membranes

Biochemical Journal ◽

10.1042/bcj20190080 ◽

2019 ◽

Vol 476 (20) ◽

pp. 2981-3018 ◽

Cited By ~ 8

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.

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Suitability Analysis of 17 Probiotic Type Strains of Lactic Acid Bacteria as Starter for Kimchi Fermentation

Foods ◽

10.3390/foods10061435 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1435

Author(s):

Hee Seo ◽

Jae-Han Bae ◽

Gayun Kim ◽

Seul-Ah Kim ◽

Byung Hee Ryu ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Growth Rates ◽

Principal Component ◽

Fermented Foods ◽

Suitability Analysis ◽

Moderate Growth ◽

Health Promoting ◽

Highly Correlated ◽

Type Strains

The use of probiotic starters can improve the sensory and health-promoting properties of fermented foods. This study aimed to evaluate the suitability of probiotic lactic acid bacteria (LAB) as a starter for kimchi fermentation. Seventeen probiotic type strains were tested for their growth rates, volatile aroma compounds, metabolites, and sensory characteristics of kimchi, and their characteristics were compared to those of Leuconostoc (Le.) mesenteroides DRC 1506, a commercial kimchi starter. Among the tested strains, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Lacticaseibacillus rhamnosus, Lacticaseibacillus paracasei, and Ligilactobacillus salivarius exhibited high or moderate growth rates in simulated kimchi juice (SKJ) at 37 °C and 15 °C. When these five strains were inoculated in kimchi and metabolite profiles were analyzed during fermentation using GC/MS and 1H-NMR, data from the principal component analysis (PCA) showed that L. fermentum and L. reuteri were highly correlated with Le. mesenteroides in concentrations of sugar, mannitol, lactate, acetate, and total volatile compounds. Sensory test results also indicated that these three strains showed similar sensory preferences. In conclusion, L. fermentum and L. reuteri can be considered potential candidates as probiotic starters or cocultures to develop health-promoting kimchi products.

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