Foreword

Julian J. Eaton-Rye

Photosynthetica 2018, 56(1):1-10 | DOI: 10.1007/s11099-018-0796-6  

Synthesis and characterization of a cobalt(II) tetrakis(3-fluorophenyl) porphyrin with a built-in 4-vinylphenyl surface attachment moiety

D. Khusnutdinova, M. Flores, A. M. Beiler, G. F. Moore

Photosynthetica 2018, 56(1):67-74 | DOI: 10.1007/s11099-018-0783-y  

Metalloporphyrins serve important roles in biology and as components in emerging technological assemblies for energy conversion. In this report, we describe the synthesis and characterization of a novel cobalt(II) 5,10,15,20-tetrakis (3-fluorophenyl)porphyrin bearing a 4-vinylphenyl surface attachment group at a beta position on the macrocycle. Electrochemical measurements show the 3-fluorophenyl groups at the meso positions of the porphyrin perturb the reduction potentials of the complex to more positive values as compared to non-fluorinated analogs, thus allowing access to reduced cobalt porphyrin species at significantly less negative applied bias...

On Otto Warburg, Nazi Bureaucracy and the difficulties of moral judgment

K. Nickelsen

Photosynthetica 2018, 56(1):75-85 | DOI: 10.1007/s11099-018-0773-0  

Twentieth-century photosynthesis research had strong roots in Germany, with the cell physiologist Otto H. Warburg being among its most influential figures. He was also one of the few scientists of Jewish ancestry who kept his post as a director of a research institution throughout the Nazi period. Based on archival sources, the paper investigates Warburg's fate during these years at selected episodes. He neither collaborated with the regime nor actively resisted; he was harrassed by bureaucracy and denunciated to the secret police, but saved by powerful figures in economy, politics, and science. Warburg reciprocated this favour with problematic testimonies...

Fluorescence induction of photosynthetic bacteria

G. Sipka, M. Kis, J. L. Smart, P. Maróti

Photosynthetica 2018, 56(1):125-131 | DOI: 10.1007/s11099-017-0756-6  

The kinetics of bacteriochlorophyll fluorescence in intact cells of the purple nonsulfur bacterium Rhodobacter sphaeroides were measured under continuous and pulsed actinic laser diode (808 nm wavelength and maximum 2 W light power) illumination on the micro- and millisecond timescale. The fluorescence induction curve was interpreted in terms of a combination of photochemical and triplet fluorescence quenchers and was demonstrated to be a reflection of redox changes and electron carrier dynamics. By adjustment of the conditions of single and multiple turnovers of the reaction center, we obtained 11 ms^-1 and 120 μs^-1...

On the quantitative relation between dark kinetics of NPQ-induced changes in variable fluorescence and the activation state of the CF₀.CF₁.ATPase in leaves

W.J. Vredenberg

Photosynthetica 2018, 56(1):139-149 | DOI: 10.1007/s11099-018-0772-1  

The variable fluorescence at the maximum F_m of the fluorescence induction (Kautsky) curve is known to be substantially suppressed shortly after light adaption due to nonphotochemical q_E quenching. The kinetic pattern of the dark decay at F_m consists of three components with rates ~20, ~1, and ~0.1 s^-1, respectively. Light adaptation has no or little effect on these rate constants. It causes a decrease in the ratio between the amplitudes of the slow and fast one with negligible change in the small amplitude of the ultra-slow component. Results add to evidence for the hypothesis that the dark-reversible decrease...

Control of the maximal chlorophyll fluorescence yield by the Q_B binding site

O. Prášil, Z. S. Kolber, P. G. Falkowski

Photosynthetica 2018, 56(1):150-162 | DOI: 10.1007/s11099-018-0768-x  

Differences in maximal yields of chlorophyll variable fluorescence (F_m) induced by single turnover (ST) and multiple turnover (MT) excitation are as great as 40%. Using mutants of Chlamydomonas reinhardtii we investigated potential mechanisms controlling F_m above and beyond the Q_A redox level. F_m was low when the Q_B binding site was occupied by PQ and high when the Q_B binding site was empty or occupied by a PSII herbicide. Furthermore, in mutants with impaired rates of plastoquinol reoxidation, F_m was reached rapidly during MT excitation. In PSII particles with no mobile...

Early emergence of the FtsH proteases involved in photosystem II repair

S. Shao, T. Cardona, P. J. Nixon

Photosynthetica 2018, 56(1):163-177 | DOI: 10.1007/s11099-018-0769-9  

Efficient degradation of damaged D1 during the repair of PSII is carried out by a set of dedicated FtsH proteases in the thylakoid membrane. Here we investigated whether the evolution of FtsH could hold clues to the origin of oxygenic photosynthesis. A phylogenetic analysis of over 6000 FtsH protease sequences revealed that there are three major groups of FtsH proteases originating from gene duplication events in the last common ancestor of bacteria, and that the FtsH proteases involved in PSII repair form a distinct clade branching out before the divergence of FtsH proteases found in all groups of anoxygenic phototrophic bacteria. Furthermore, we...

PsbP-induced protein conformational changes around Cl^- ions in the water oxidizing center of photosystem II

J. Kondo, T. Noguchi

Photosynthetica 2018, 56(1):178-184 | DOI: 10.1007/s11099-017-0749-5  

PsbP is an extrinsic protein of PSII having a function of Ca²⁺ and Cl^- retention in the water-oxidizing center (WOC). In order to understand the mechanism how PsbP regulates the Cl^- binding in WOC, we examined the effect of PsbP depletion on the protein structures around the Cl^- sites using Fourier transform infrared (FTIR) spectroscopy. Light-induced FTIR difference spectra upon the S¹→S₂ transition were obtained using Cl^--bound and NO₃^--substituted PSII membranes in the presence and absence of PsbP. A clear difference in the amide I band changes...

The PsbQ' protein affects the redox potential of the Q_A in photosystem II

M. Yamada, R. Nagao, M. Iwai, Y. Arai, A. Makita, H. Ohta, T. Tomo

Photosynthetica 2018, 56(1):185-191 | DOI: 10.1007/s11099-018-0778-8  

Red alga contains four extrinsic proteins in photosystem II (PSII), which are PsbO, PsbV, PsbU, and PsbQ'. Except for the PsbQ', the composition is the same in cyanobacterial PSII. Reconstitution analysis of cyanobacterial PSII has shown that oxygen-evolving activity does not depend on the presence of PsbQ'. Recently, the structure of red algal PSII was elucidated. However, the role of PsbQ' remains unknown. In this study, the function of the acceptor side of PSII was analyzed in PsbQ'-reconstituted PSII by redox titration of Q_A and thermoluminescence. The redox potential of Q_A was positively shifted when PsbQ' was attached to...

Regulating photoprotection improves photosynthetic growth and biomass production in Q_C-site mutant cells of the cyanobacterium Synechocystis sp. PCC 6803

J. Y. Huang, N. T. Hung, K. M. Lin, Y. F. Chiu, H. A. Chu

Photosynthetica 2018, 56(1):192-199 | DOI: 10.1007/s11099-018-0765-0  

We characterized the photosynthetic growth of wild-type (WT) and QC-site mutant cells of the cyanobacterium Synechocystis sp. PCC 6803 grown in a photobioreactor under medium-intensity [~70 μmol(photon) m^-2 s^-1] and high-intensity [~200 μmol(photon) m^-2 s^-1] light conditions. Photosynthetic growth rate (the exponential phase) increased about 1.1-1.2 fold for the A16FJ, S28Aβ, and V32Fβ mutant compared with WT cells under medium-intensity light and about 1.2-1.3 fold under high-intensity light. Biomass production increased about 17-20% for A16FJ and S28Aβ mutant cells as compared...

PsbY is required for prevention of photodamage to photosystem II in a PsbM-lacking mutant of Synechocystis sp. PCC 6803

S. Biswas, J. J. Eaton-Rye

Photosynthetica 2018, 56(1):200-209 | DOI: 10.1007/s11099-018-0788-6  

The PsbM (3.9 kDa) and PsbY (4.2 kDa) proteins are membrane-spanning, single-helix, subunits associated with the chlorophyll-binding CP47 pre-complex of photosystem II (PSII). Removal of PsbM resulted in accumulation of PSII pre-assembly complexes and impaired electron transfer between the primary (Q_A) and secondary (Q_B) plastoquinone electron acceptors of PSII indicating that the Q_B-binding site and bicarbonate binding to the non-heme iron were altered in this strain. Removal of PsbY alone had only a minor impact on PSII activity but deleting PsbY in the ΔPsbM background led to additional modification of the...

Quantification of bound bicarbonate in photosystem II

K. Tikhonov, D. Shevela, V. V. Klimov, J. Messinger

Photosynthetica 2018, 56(1):210-216 | DOI: 10.1007/s11099-017-0758-4  

In this study, we presented a new approach for quantification of bicarbonate (HCO₃^-) molecules bound to PSII. Our method, which is based on a combination of membrane-inlet mass spectrometry (MIMS) and ¹⁸O-labelling, excludes the possibility of "non-accounted" HCO₃^- by avoiding (1) the employment of formate for removal of HCO₃^- from PSII, and (2) the extremely low concentrations of HCO₃^-/CO₂ during online MIMS measurements. By equilibration of PSII sample to ambient CO₂ concentration of dissolved CO₂/HCO₃^-,...

The multiplicity of roles for (bi)carbonate in photosystem II operation in the hypercarbonate-requiring cyanobacterium Arthrospira maxima

G. Ananyev, C. Gates, G. C. Dismukes

Photosynthetica 2018, 56(1):217-228 | DOI: 10.1007/s11099-018-0781-0  

Arthrospira maxima is unique among cyanobacteria, growing at alkaline pH (<11) in concentrated (bi)carbonate (1.2 M saturated) and lacking carbonic anhydrases. We investigated dissolved inorganic carbon (DIC) roles within PSII of A. maxima cells oximetrically and fluorometrically, monitoring the light reactions on the donor and acceptor sides of PSII. We developed new methods for removing DIC based on a (bi)carbonate chelator and magnesium for (bi)carbonate ionpairing. We established relative affinities of three sites: the water-oxidizing complex (WOC), non-heme iron/Q_A^-, and solvent-accessible arginines throughout...

Analysis of photosystem II electron transfer with natural PsbA-variants by redox polymer/protein biophotoelectrochemistry

V. Hartmann, A. Ruff, W. Schuhmann, M. Rögner, M. M. Nowaczyk

Photosynthetica 2018, 56(1):229-235 | DOI: 10.1007/s11099-018-0775-y  

Redox polymer/protein biophotoelectrochemistry was used to analyse forward electron transfer of isolated PSII complexes with natural PsbA-variants. PsbA1- or PsbA3-PSII was embedded in a redox hydrogel that allows diffusion-free electron transfer to the electrode surface and thus measurement of an immediate photocurrent response. The initial photocurrent density of the electrode is up to ~2-fold higher with PsbA1-PSII under all tested light conditions, the most prominent under high-light [2,300 μmol(photon) m^-2 s^-1] illumination with 5 μA cm^-2 for PsbA3-PSII and 9.5 μA cm^-2 for PsbA1-PSII. This indicates...

Influence of the disaccharide trehalose on the oxidizing side of photosystem II

M. D. Mamedov, E. S. Nosikova, L. A. Vitukhnovskaya, A. A. Zaspa, A. Yu. Semenov

Photosynthetica 2018, 56(1):236-243 | DOI: 10.1007/s11099-017-0750-z  

The steady-state oxygen evolution rate was previously shown to be stimulated by the disaccharide trehalose in PSII suspension. Here we showed a similar increase in the rate of oxygen evolution in PSII core complexes from spinach in solution and in proteoliposomes in the presence of trehalose. Using direct electrometrical technique, we also revealed that trehalose had no effect on the kinetics of electron transfer from Mn to redox-active-tyrosyl radical, Y_Z^* (S₁ → S₂ transition), while it accelerated the kinetics of electrogenic proton transport during S₂ → S₃ and S₄...

Photooxidation and photoreduction of exogenous cytochrome c by photosystem II preparations after various modifications of the water-oxidizing complex

A. A. Khorobrykh, D. V. Yanykin, V. V. Klimov

Photosynthetica 2018, 56(1):244-253 | DOI: 10.1007/s11099-017-0762-8  

The redox interaction of exogenous cytochrome c₅₅₀ (Cyt) with PSII isolated from spinach was studied. Illumination of PSII particles in the presence of Cyt led to: (1) Cyt photooxidation by PSII reaction center (demonstrated at the first time), (2) Cyt photoreduction via O₂^-* photoproduced on the acceptor side of PSII, and (3) Cyt photoreduction by reduced electron carriers of PSII. A step-by-step removal of components of water-oxidizing complex was accompanied by the appearance of Cyt photooxidation, an increase in the superoxide dismutase (SOD)-dependent Cyt photoreduction (related...

Increased thermal stability of photosystem II and the macro-organization of thylakoid membranes, induced by co-solutes, associated with changes in the lipid-phase behaviour of thylakoid membranes

C. Kotakis, P. Akhtar, O. Zsiros, G. Garab, P. H. Lambrev

Photosynthetica 2018, 56(1):254-264 | DOI: 10.1007/s11099-018-0782-z  

The principal function of the thylakoid membrane depends on the integrity of the lipid bilayer, yet almost half of the thylakoid lipids are of non-bilayer-forming type, whose exact functions are not fully understood. Non-bilayer lipids can be extruded from the membrane in the presence of high concentrations of co-solutes. We applied 2 M sucrose to induce lipid phase separation in isolated thylakoid membranes, following consequent structural and physiological effects. Circular dichroism spectroscopy indicated significant changes in the chiral macro-arrangement of the pigment-protein complexes, which were reversed after washing out the co-solute. Similarly,...

The phycobilisome terminal emitter transfers its energy with a rate of (20 ps)^-1 to photosystem II

A. M. Acuña, P. Van Alphen, R. Van Grondelle, I. H. M. Van Stokkum

Photosynthetica 2018, 56(1):265-274 | DOI: 10.1007/s11099-018-0779-7  

Ultrafast time resolved emission spectra were measured in whole cells of a PSI-deficient mutant of Synechocystis sp. PCC 6803 at room temperature and at 77K to study excitation energy transfer and trapping. By means of a target analysis it was estimated that the terminal emitter of the phycobilisome, termed allophycocyanin 680, transfers its energy with a rate of (20 ps)^-1 to PSII. This is faster than the intraphycobilisome energy transfer rates between a rod and a core cylinder, or between the core cylinders.

Determination of PS I oligomerisation in various cyanobacterial strains and mutants by non-invasive methods

T. Zakar, L. Kovacs, S. Vajravel, E. Herman, M. Kis, H. Laczko-Dobos, Z. Gombos

Photosynthetica 2018, 56(1):294-299 | DOI: 10.1007/s11099-018-0795-7  

PSI trimer to monomer ratio in intact cyanobacterial cells and isolated thylakoids was analysed by two noninvasive, in vivo methods; low-temperature fluorescence emission and circular dichroism spectroscopy. We measured fluorescence emission spectra of cells upon chlorophyll (Chl, 436 nm) excitation. All three species - Synechocystis sp. PCC 6803, Anabaena sp. PCC 7120, and Spirulina platensis - showed shifted Chl peak, indicating they have different spectral properties. CD spectroscopy revealed the highest intensity at 515 nm (PSI peak) in Spirulina platensis cells, which may originate from PSI multi-oligomerisation....

Characterization of isolated photosystem I from Halomicronema hongdechloris, a chlorophyll f-producing cyanobacterium

Y. Li, N. Vella, M. Chen

Photosynthetica 2018, 56(1):306-315 | DOI: 10.1007/s11099-018-0776-x  

Halomicronema hongdechloris is a chlorophyll (Chl) f-producing cyanobacterium. Chl f biosynthesis is induced under far-red light, extending its photosynthetically active radiation range to 760 nm. In this study, PSI complexes were isolated and purified from H. hongdechloris, grown under white light (WL) and far-red light (FR), by a combination of density gradient ultracentrifugation and chromatographic separation. WL-PSI showed similar pigment composition as that of Synechocystis 6803, using Chl a in the reaction center. Both Chl a and f were detected in the FR-PSI, although Chl f was a...

Effect of green light on the amount and activity of NDH-1-PSI supercomplex in Synechocystis sp. strain PCC 6803

F. Gao, T. Ogawa, W. Ma

Photosynthetica 2018, 56(1):316-321 | DOI: 10.1007/s11099-018-0790-z  

Cyanobacterial NDH-1 interacts with PSI to form NDH-1-PSI supercomplex. CpcG2, a linker protein for the PSI-specific peripheral antenna CpcG2-phycobilisome, is essential for stabilization of the supercomplex. Green light (GL) increased the expression of CpcG2 but had little effect, if any, on the expression of NDH-1 and PSI, when compared to the abundance of these components under red light (RL). The increased expression of CpcG2 intensified the band of NDH-1-PSI supercomplex after blue-native gel electrophoresis of the thylakoid membrane, possibly by stabilizing the supercomplex. The activity of NDH-1-dependent cyclic electron transport around PSI...

Factors affecting photobiological hydrogen production in five filamentous cyanobacteria from Thailand

P. Yodsang, W. Raksajit, E-M. Aro, P. Mäenpää, A. Incharoensakdi

Photosynthetica 2018, 56(1):334-341 | DOI: 10.1007/s11099-018-0789-5  

We report here the screening of sixteen cyanobacterial and three green algal strains from Thailand for their potential biohydrogen production. Five filamentous cyanobacterial species, namely Calothrix elenkinii, Fischerella muscicola, Nostoc calcicola, Scytonema bohneri, and Tolypothrix distorta, all possessing nitrogenase activity, showed potentially high biohydrogen production. These five strains showed higher hydrogen production in the absence than in the presence of nitrogen. In particular, F. muscicola had a 17-fold increased hydrogen production under combined nitrogen and sulfur deprived conditions. Among...

Leptolyngbya CCM 4, a cyanobacterium with far-red photoacclimation from Cuatro Ciénegas Basin, México

C. Gómez-Lojero, L. E. Leyva-Castillo, P. Herrera-Salgado, J. Barrera-Rojas, E. Ríos-Castro, E. B. Gutiérrez-Cirlos

Photosynthetica 2018, 56(1):342-353 | DOI: 10.1007/s11099-018-0774-z  

A cyanobacterium containing phycobiliproteins with far-red acclimation was isolated from Pozas Rojas, Cuatro Ciénegas, México. It was named Leptolyngbya CCM 4 after phylogenetic analysis and a description of its morphological characteristics. Leptolyngbya was grown in far-red light. Sucrose-gradient analysis of the pigments revealed two different colored bands of phycobiliproteins. A band at 60% sucrose was a phycocyanin containing phycobilisome; at 35% sucrose, a new type of phycobiliprotein absorbed at 710 nm. SDS-PAGE revealed the presence of two types of core-membrane linkers. Analysis of the hydrophobic pigments extracted from the...

Tocopherols modulate leaf vein arrangement and composition without impacting photosynthesis

J. J. Stewart, W. W. Adams, C. M. Cohu, B. Demmig-Adams

Photosynthetica 2018, 56(1):382-391 | DOI: 10.1007/s11099-017-0757-5  

Growth of the tocopherol-deficient vte1 mutant and Col-0 wild type of Arabidopsis thaliana in a sunlit glasshouse revealed both similarities and differences between genotypes. Photosynthetic capacity and leaf mesophyll features did not differ between mutant and wild type. Likewise, the total volume of water conduits (tracheary elements, TEs), sugar conduits (sieve elements, SEs), and sugar-loading cells (companion and phloem parenchyma cells) on a leaf area basis were unaffected by tocopherol deficiency. However, tocopherol deficiency yielded smaller and more numerous minor veins with fewer phloem cells and smaller TEs, resulting in greater...

Evaluating the link between photosynthetic capacity and leaf vascular organization with principal component analysis

S. K. Polutchko, J. J. Stewart, B. Demmig-Adams, W. W. Adams

Photosynthetica 2018, 56(1):392-403 | DOI: 10.1007/s11099-017-0764-6  

Significant linear relationships between photosynthetic capacity and principal components loaded by phloem cell numbers and tracheary elements per minor vein as well as the latter two normalized for vein density (proxy for apoplastic phloem loading capacity involving membrane transporters) were revealed for all apoplastic loaders (summer annuals and winter annual Arabidopsis thaliana). In addition, significant linear relationships between photosynthetic capacity and a principal component loaded by tracheary element cross-sectional areas and volumes per unit of leaf area (water flux capacity proxy) was present for symplastic and apoplastic loaders....

Brandt iH026a plant growth regulator

A. M. Nonomura, A. Pedersen, D. P. Brummel, L. Loveless, A. Lauria, B. Haschemeyer, M. S. McBride

Photosynthetica 2018, 56(1):411-417 | DOI: 10.1007/s11099-017-0739-7  

iH026a is a formulation containing a biochemical class of plant growth regulator that modulates glycoconjugation through the plant lectin cycle. While lectins are common to vascular plants, we observed, consistent with reversible binding of sugars from lectins, enhancements of quantities and qualities of various features, including significant enrichment of Brix soluble sugars compared to controls in cherry, grape, and melon in trials conducted in Arizona and California, USA.

Response of photosynthetic apparatus in Arabidopsis thaliana L. mutant deficient in phytochrome A and B to UV-B

V. D. Kreslavski, A. N. Shmarev, V. Yu. Lyubimov, G. A. Semenova, S. K. Zharmukhamedov, G. N. Shirshikova, A. Yu. Khudyakova, S. I. Allakhverdiev

Photosynthetica 2018, 56(1):418-426 | DOI: 10.1007/s11099-017-0754-8  

The effects of UV-B radiation (1 W m^-2, 1 and 2 h) on PSII activity, chloroplast structure, and H₂O₂ contents in leaves of 26-d-old Arabidopsis thaliana phyA phyB double mutant (DMut) compared with the wild type (WT) were investigated. UV-B decreased PSII activity and affected the H₂O₂ content in WT and DMut plants grown under white light (WL). The chloroplast structure changes in DMut plants exposed to UV were more significant than that in WT. Reductions in maximal and real quantum photochemical yields and increase in the value of thermal dissipation of absorbed light energy per PSII RC...

Susceptibility of an ascorbate-deficient mutant of Arabidopsis to high-light stress

L. D. Zeng, M. Li, W. S. Chow, C. L. Peng

Photosynthetica 2018, 56(1):427-432 | DOI: 10.1007/s11099-017-0759-3  

Ascorbate is an important antioxidant involved in both enzymatic and nonenzymatic reactions in plant cells. To reveal the function of ascorbate associated with defense against photo-oxidative damage, responses of the ascorbate-deficient mutant vtc2-1 of Arabidopsis thaliana to high-light stress were investigated. After high-light treatment at 1,600 μmol(photon) m^-2 s^-1 for 8 h, the vtc2-1 mutant exhibited visible photo-oxidative damage. The total ascorbate content was lower, whereas accumulation of H₂O₂ was higher in the vtc2-1 mutant than that in the wild type. The chlorophyll...

Improved photosynthesis in Arabidopsis roots by activation of GATA transcription factors

A. Ohnishi, H. Wada, K. Kobayashi

Photosynthetica 2018, 56(1):433-444 | DOI: 10.1007/s11099-018-0785-9  

Plant cells plastically change their functions according to the environment. Although Arabidopsis roots are heterotrophic organs, they increase photosynthetic capacity after shoot removal. Transcription factors regulating chloroplast development are involved in this response downstream of positive cytokinin and negative auxin regulation. To dissect the crosstalk of these regulators after shoot removal, we analyzed photosynthetic parameters in roots with chloroplast development enhanced by shoot removal, overexpression of transcription factors, or hormonal treatment. Our data suggest that shoot removal improves electron transfer downstream of...

Anthocyanins function as a light attenuator to compensate for insufficient photoprotection mediated by nonphotochemical quenching in young leaves of Acmena acuminatissima in winter

H. Zhu, T. J. Zhang, J. Zheng, X. D. Huang, Z. C. Yu, C. L. Peng, W. S. Chow

Photosynthetica 2018, 56(1):445-454 | DOI: 10.1007/s11099-017-0740-1  

Anthocyanins and nonphotochemical quenching (NPQ) are two important tools that provide photoprotection in plant leaves. In order to understand how plants use these tools for acclimation to changing seasonal conditions, we investigated pigments, antioxidative capacity, and photosynthesis in leaves of an evergreen tree (Acmena acuminatissima) in two contrasting seasons. Young leaves of A. acuminatissima appeared in distinct colors, being light green in summer and red in winter due to the presence of anthocyanins. In the winter young leaves, anthocyanins contributed less than 2% to the antioxidant pool. In the summer, young leaves had higher...

Community-wide consequences of variation in photoprotective physiology among prairie plants

S. Kothari, J. Cavender-Bares, K. Bitan, A. S. Verhoeven, R. Wang, R. A. Montgomery, J. A. Gamon

Photosynthetica 2018, 56(1):455-467 | DOI: 10.1007/s11099-018-0777-9  

Photoprotective pigments, like those involved in the xanthophyll cycle, help plants avoid oxidative damage caused by excess radiation. This study aims to characterize a spectrum of strategies used to cope with light stress by a diverse group of prairie plants at Cedar Creek Ecosystem Science Reserve (East Bethel, MN). We find that concentrations of photosynthetic and photoprotective pigments are highly correlated with one another and with other physiological traits across species and over time, and tend to be phylogenetically conserved. During a period of water limitation, plots dominated by species with constitutively low pigment concentrations showed...

Adaptation strategies of two leaf cohorts of Prosopis juliflora produced in spring and monsoon

P. A. Shirke, U. V. Pathre, P. V. Sane

Photosynthetica 2018, 56(1):468-477 | DOI: 10.1007/s11099-018-0794-8  

Prosopis juliflora is an invasive leguminous tree species growing profusely under wide environmental conditions. Primary objective of this study was to investigate adaptation strategies evolved to deal with wide environmental conditions during different seasons. P. juliflora adapts through a production of leaves in two seasons, namely, the spring (the first cohort) and monsoon (the second cohort) with differing but optimal physiological characteristics for growth in respective seasons. Our studies show that the first cohort of leaves exhibit maximum carbon fixation under moderate temperatures and a wide range of PPFD. However, these leaves...

Living off the Sun: chlorophylls, bacteriochlorophylls and rhodopsins

A. W. D. Larkum, R. J. Ritchie, J. A. Raven

Photosynthetica 2018, 56(1):11-43 | DOI: 10.1007/s11099-018-0792-x  

Pigments absorbing 350-1,050 nm radiation have had an important role on the Earth for at least 3.5 billion years. The ion pumping rhodopsins absorb blue and green photons using retinal and pump ions across cell membranes. Bacteriochlorophylls (BChl), absorbing in the violet/blue and near infra red (NIR), power anoxygenic photosynthesis, with one photoreaction centre; and chlorophylls (Chl), absorbing in the violet/blue and red (occasionally NIR) power oxygenic photosynthesis, with two photoreaction centres. The accessory (bacterio)chlorophylls add to the spectral range (bandwidth) of photon absorption, e.g., in algae living at depth in clear...

RNA editing of plastid-encoded genes

Y. Lu

Photosynthetica 2018, 56(1):48-61 | DOI: 10.1007/s11099-017-0761-9  

RNA editing is post-transcriptional modification to RNA molecules. In plants, RNA editing primarily occurs to two energy-producing organelles: plastids and mitochondria. Organelle RNA editing is often viewed as a mechanism of correction to compensate for defects or mutations in haploid organelle genomes. A common type of organelle RNA editing is deamination from cytidine to uridine. Cytidine-to-uridine plastid RNA editing is carried out by the RNA editing complex which consists of at least four types of proteins: pentatricopeptide repeat proteins, RNA editing interacting proteins/multiple organellar RNA editing factors, organelle RNA recognition motif...

Chlorophyll a fluorescence induction: Can just a one-second measurement be used to quantify abiotic stress responses?

A. Stirbet, D. Lazár, J. Kromdijk, Govindjee

Photosynthetica 2018, 56(1):86-104 | DOI: 10.1007/s11099-018-0770-3  

Chlorophyll (Chl) a fluorescence induction (transient), measured by exposing dark-adapted samples to high light, shows a polyphasic rise, which has been the subject of extensive research over several decades. Several Chl fluorescence parameters based on this transient have been defined, the most widely used being the F_V [= (F_M-F₀)]/F_M ratio as a proxy for the maximum quantum yield of PSII photochemistry. However, considerable additional information may be derived from analysis of the shape of the fluorescence transient. In fact, several performance indices (PIs) have been defined, which are suggested...

Chlorophyll fluorescence emission spectroscopy of oxygenic organisms at 77 K

J. J. Lamb, G. Røkke, M. F. Hohmann-Marriott

Photosynthetica 2018, 56(1):105-124 | DOI: 10.1007/s11099-018-0791-y  

Photosynthetic fluorescence emission spectra measurement at the temperature of 77 K (-196°C) is an often-used technique in photosynthesis research. At low temperature, biochemical and physiological processes that modulate fluorescence are mostly abolished, and the fluorescence emission of both PSI and PSII become easily distinguishable. Here we briefly review the history of low-temperature chlorophyll fluorescence methods and the characteristics of the acquired emission spectra in oxygen-producing organisms. We discuss the contribution of different photosynthetic complexes and physiological processes to fluorescence emission at 77 K in cyanobacteria,...

Ferredoxin: the central hub connecting photosystem I to cellular metabolism

J. Mondal, B. D. Bruce

Photosynthetica 2018, 56(1):279-293 | DOI: 10.1007/s11099-018-0793-9  

Ferredoxin (Fd) is a small soluble iron-sulfur protein essential in almost all oxygenic photosynthetic organisms. It contains a single [2Fe-2S] cluster coordinated by four cysteine ligands. It accepts electrons from the stromal surface of PSI and facilitates transfer to a myriad of acceptors involved in diverse metabolic processes, including generation of NADPH via Fd-NADP-reductase, cyclic electron transport for ATP synthesis, nitrate reduction, nitrite reductase, sulfite reduction, hydrogenase and other reductive reactions. Fd serves as the central hub for these diverse cellular reactions and is integral to complex cellular metabolic networks....

Function, regulation and distribution of IsiA, a membrane-bound chlorophyll a-antenna protein in cyanobacteria

H. Y.S. Chen, A. Bandyopadhyay, H. B. Pakrasi

Photosynthetica 2018, 56(1):322-333 | DOI: 10.1007/s11099-018-0787-7  

IsiA is a membrane-bound Chl a-antenna protein synthesized in cyanobacteria under iron deficiency. Since iron deficiency is a common nutrient stress in significant fractions of cyanobacterial habitats, IsiA is likely to be essential for some cyanobacteria. However, the role it plays in cyanobacteria is not fully understood. In this review paper, we summarize the research efforts directed towards characterizing IsiA over the past three decades and attempt to bring all the pieces of the puzzle together to get a more comprehensive understanding of the function of this protein. Moreover, we analyzed the genomes of over 390 cyanobacterial strains...

Photosynthetic efficiency in sun and shade plants

S. Mathur, L. Jain, A. Jajoo

Photosynthetica 2018, 56(1):354-365 | DOI: 10.1007/s11099-018-0767-y  

Photosynthesis is amongst the plant cell functions that are highly sensitive to any type of changes. Sun and shade conditions are prevalent in fields as well as dense forests. Dense forests face extreme sun and shade conditions, and plants adapt themselves accordingly. Sun flecks cause changes in plant metabolic processes. In the field, plants have to face high light intensity and survive under such conditions. Sun and shade type of plants develops a respective type of chloroplasts which help plants to survive and perform photosynthesis under adverse conditions. PSII and Rubisco behave differently under different sun and shade conditions. In this review,...

Photosynthesis and salinity: are these mutually exclusive?

S. Wungrampha, R. Joshi, S. L. Singla-Pareek, A. Pareek

Photosynthetica 2018, 56(1):366-381 | DOI: 10.1007/s11099-017-0763-7  

Photosynthesis has walked into the path of evolution for over millions of years. Organisms relying directly on photosynthesis, when subjected to adverse environments for a long duration, experience retardation in their growth and development. Salinity stress is perceived as one of the major threats to agriculture as it can cause an irreversible damage to the photosynthetic apparatus at any developmental stage of the plant. However, halophytes, a special category of plants, carry out all life processes, including photosynthesis, without showing any compromise even under high saline environments. The fascinating mechanism for Na⁺ exclusion...

Loss of photosynthesis signals a metabolic reprogramming to sustain sugar homeostasis during senescence of green leaves: Role of cell wall hydrolases

B. Biswal, J. K. Pandey

Photosynthetica 2018, 56(1):404-410 | DOI: 10.1007/s11099-018-0784-x  

Leaf senescence is always associated with decline in photosynthesis, consequently a loss of cellular sugar. On the other hand, execution of senescence program needs energy and leaves, therefore, tend to collect sugars from other sources to sustain energy homeostasis. This sugar reprogramming induced by loss of sugar involves operation of a complex catabolic network. The exact molecular mechanism of induction and regulation of the network, however, is not fully resolved but the current literature available suggests sugar starvation as a signal for induction of several senescence-associated genes including the genes coding for the enzymes for degradation...

On oxygen production by photosynthesis: A viewpoint

A. Yu. Borisov, L. O. Björn

Photosynthetica 2018, 56(1):44-47 | DOI: 10.1007/s11099-017-0738-8  

In this brief communication we provide an estimate of the part of the incident solar energy used for oxygen evolution as well as the time, in years, needed for the generation of the present amount of molecular oxygen in the biosphere by photosynthesis on land and in the ocean. We find this to be ≈3,000 yr. We also find that the ocean produces 22% more oxygen than the land surface.

Chloroplast ribonucleoprotein-like proteins of the moss Physcomitrella patens are not involved in RNA stability and RNA editing

H. Uchiyama, M. Ichinose, M. Sugita

Photosynthetica 2018, 56(1):62-66 | DOI: 10.1007/s11099-017-0755-7  

Many RNA recognition motif (RRM)-containing proteins are known to exist in chloroplasts. Major members of the RRM protein family, which are chloroplast ribonucleoproteins (cpRNPs), have been investigated in seed plants, including tobacco and Arabidopsis thaliana, but never in early land plants, such as bryophytes. In this study, we surveyed RRM proteins encoded in the moss Physcomitrella patens genome and predicted 25 putative chloroplast RRM proteins. Among them, two RRM-containing proteins, PpRBP2a and PpRBP2b, resembled cpRNPs and were thus referred to as cpRNP-like proteins. However, knockout mutants of either one or two PpRBP2...

Application of spectrally resolved fluorescence induction to study light-induced nonphotochemical quenching in algae

R. Kaňa

Photosynthetica 2018, 56(1):132-138 | DOI: 10.1007/s11099-018-0780-1  

The light-induced nonphotochemical quenching (NPQ) can safely dissipate excess of absorbed light to heat. Here we describe an application of spectrally resolved fluorescence induction (SRFI) method for studying spectral variability of NPQ. The approach allows detection of spectrally-resolved nonphotochemical quenching (NPQ_λ) representing NPQ dependency on fluorescence emission wavelength in the whole spectral range of fluorescence emission. The experimental approach is briefly described and NPQ_λ is studied for the cryptophyte alga Rhodomonas salina and for green alga Chlorella sp. We confirm presence...

The deep red state of photosystem II in Cyanidioschyzon merolae

J. Langley, J. Morton, R. Purchase, L. Tian, L. Shen, G. Han, J. R. Shen, E. Krausz

Photosynthetica 2018, 56(1):275-278 | DOI: 10.1007/s11099-017-0760-x  

We identified and characterised the deep red state (DRS), an optically-absorbing charge transfer state of PSII, which lies at lower energy than P680, in the red algae Cyanidioschyzon merolae by means of low temperature absorption and magnetic circular dichroism spectroscopies. The photoactive DRS has been previously studied in PSII of the higher plant Spinacia oleracea, and in the cyanobacterium Thermosynechococcus vulcanus. We found the DRS in PSII of C. merolae has similar spectral properties. Treatment of PSII with dithionite leads to reduction of cytochrome (cyt) b₅₅₉ and the PsbV-based cyt c₅₅₀...

Isolation of the cyanobacterial YFP-tagged photosystem I using GFP-Trap®

A. Strašková, J. Knoppová, J. Komenda

Photosynthetica 2018, 56(1):300-305 | DOI: 10.1007/s11099-018-0771-2  

A strain of Synechocystis sp. PCC 6803 expressing the yellow fluorescent protein (YFP) fused to the C-terminus of the PsaF subunit of PSI has been constructed and used to isolate native PSI complexes employing the GFP-Trap®, an efficient immunoprecipitation system which recognizes the green fluorescent protein (GFP) and its variants. The protein analysis and spectroscopic characterization of the preparation revealed an isolate of trimeric and monomeric PSI complexes, which showed minimal unspecific contamination as demonstrated by comparison with the wild type control. Interestingly, we detected CP43 subunits of PSII and small amounts...