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Photosynthesis Research

Takashi Moriyama, Natsumi Mori, Noriko Nagata, Naoki Sato
We previously found that glycerol is required for heterotrophic growth in the unicellular red alga Cyanidioschyzon merolae. Here, we analyzed heterotrophically grown cells in more detail. Sugars or other organic substances did not support the growth in the dark. The growth rate was 0.4 divisions day-1 in the presence of 400 mM glycerol, in contrast with 0.5 divisions day-1 in the phototrophic growth. The growth continued until the sixth division. Unlimited heterotrophic growth was possible in the medium containing DCMU and glycerol in the light...
November 10, 2018: Photosynthesis Research
Zuzana Münzbergová, Daniel Haisel
The contents of photosynthetic pigments are an important indicator of many processes taking place in the plant body. Still, however, our knowledge of the effects of polyploidization, a major driver of speciation in vascular plants, on the contents of photosynthetic pigments is very sparse. We compared the contents of photosynthetic pigments among natural diploids, natural tetraploids, and synthetic tetraploids. The material originated from four natural mixed-cytotype populations of diploid and autotetraploid Vicia cracca (Fabaceae) occurring in the contact zone between the cytotypes in Central Europe and was cultivated under uniform conditions...
November 9, 2018: Photosynthesis Research
Andrei Razjivin, Alexander Solov'ev, Victor Kompanets, Sergey Chekalin, Andrey Moskalenko, Heiko Lokstein
A comparative two-photon excitation spectroscopic study of the exciton structure of the core antenna complex (LH1) and its subunit B820 was carried out. LH1 and its subunit B820 were isolated from cells of the carotenoid-less mutant G9 of Rhodospirillum rubrum. The measurements were performed by two-photon pump-probe spectroscopy. Samples were excited by 70 fs pulses at 1390 nm at a frequency of 1 kHz. Photoinduced absorption changes were recorded in the spectral range from 780 to 1020 nm for time delays of the probe pulse relative to the pump pulse in the - 1...
November 8, 2018: Photosynthesis Research
Steven M Theg
No abstract text is available yet for this article.
November 5, 2018: Photosynthesis Research
Mai Duy Luu Trinh, Ryoichi Sato, Shinji Masuda
Precise control of the proton concentration gradient across thylakoid membranes (ΔpH) is essential for photosynthesis and its regulation because the gradient contributes to the generation of the proton motive force used for ATP synthesis and also for the fast and reversible induction of non-photochemical quenching (NPQ) to avoid photoinhibition and photodamage. However, the regulatory mechanism(s) controlling ΔpH in response to fluctuating light has not been fully elucidated. We previously described a new NPQ-regulatory chloroplastic protein, Fluctuating-Light-Acclimation Protein1 (FLAP1), which is important for plant growth and modulation of ΔpH under fluctuating light conditions...
November 2, 2018: Photosynthesis Research
Julian J Eaton-Rye
No abstract text is available yet for this article.
October 31, 2018: Photosynthesis Research
Ottó Zsiros, Valéria Nagy, Árpád Párducz, Gergely Nagy, Renáta Ünnep, Hassan El-Ramady, József Prokisch, Zsuzsa Lisztes-Szabó, Miklós Fári, József Csajbók, Szilvia Zita Tóth, Győző Garab, Éva Domokos-Szabolcsy
Selenium (Se) is a natural trace element, which shifts its action in a relatively narrow concentration range from nutritional role to toxicity. Although it has been well established that in plants chloroplasts are among the primary targets, the mechanism of toxicity on photosynthesis is not well understood. Here, we compared selenate and red-allotrope elemental selenium nanoparticles (red nanoSe) in in vitro tobacco cultures to investigate their effects on the structure and functions of the photosynthetic machinery...
October 29, 2018: Photosynthesis Research
Thomas D Sharkey
It has been 65 years since the Calvin-Benson cycle was first formulated. In this paper, the development of the concepts that are critical to the cycle is traced and the contributions of Calvin, Benson, and Bassham are discussed. Some simplified views often found in text books such as ascending paper chromatography and the use of the "lollipop" for short labeling are discussed and further details given. Key discoveries that underpinned elucidation of the cycle such as the importance of sedoheptulose phosphate and ribulose 1,5-bisphosphate are described...
October 29, 2018: Photosynthesis Research
Beat Keller, Imre Vass, Shizue Matsubara, Kenny Paul, Christoph Jedmowski, Roland Pieruschka, Ladislav Nedbal, Uwe Rascher, Onno Muller
Photosynthetic phenotyping requires quick characterization of dynamic traits when measuring large plant numbers in a fluctuating environment. Here, we evaluated the light-induced fluorescence transient (LIFT) method for its capacity to yield rapidly fluorometric parameters from 0.6 m distance. The close approximation of LIFT to conventional chlorophyll fluorescence (ChlF) parameters is shown under controlled conditions in spinach leaves and isolated thylakoids when electron transport was impaired by anoxic conditions or chemical inhibitors...
October 24, 2018: Photosynthesis Research
Hellen Oliveira de Oliveira, Gledson Luiz Salgado de Castro, Lorena Oliveira Correa, Walter Vellasco Duarte Silvestre, Sidney Vasconcelos do Nascimento, Rafael Borges da Silva Valadares, Guilherme Corrêa de Oliveira, Rodolfo Inacio Nunes Santos, Reginaldo Alves Festucci-Buselli, Hugo Alves Pinheiro
This study examined whether drought sensitivity in açaí (Euterpe oleracea Mart.) is associated with reductions in photosynthesis and increasing oxidative stress in response to down-regulation of proteins related to photosynthetic reactions, photorespiration, and antioxidant system. Well-watered (Control) and drought-stressed plants were compared when leaf water potential in stressed plants reached around - 1.5 and - 3.0 MPa, representing moderate and severe drought. Drought caused 84 and 96% decreases in net photosynthetic rate (Pn ) and stomatal conductance...
October 24, 2018: Photosynthesis Research
Cosmin Ionel Sicora, Iuliana Chiș, Ciprian Chiș, Oana Sicora
Cyanobacteria, as well as green algae and higher plants, have highly conserved photosynthetic machinery. Cyanothece sp. ATCC 51142 is a unicellular, aerobic, diazotrophic cyanobacterium that fixes N2 in the dark. In Cyanothece, the psbA gene family is composed of five members, encoding different isoforms of the D1 protein. A new D1 protein has been postulated in the literature, which blocks PSII during the night and allows the fixation of nitrogen. We present data showing changes in PSII function in cells grown in cycles alternating between 12 h of light and dark, respectively, at Cyanothece sp...
October 24, 2018: Photosynthesis Research
Peter P Knox, Boris N Korvatovskiy, Vladimir V Gorokhov, Sergey N Goryachev, Mahir D Mamedov, Vladimir Z Paschenko
The dependence on temperature of tryptophan fluorescence lifetime in trimeric photosystem I (PSI) complexes from cyanobacteria Synechocystis sp. PCC 6803 during the heating of pre-frozen to - 180 °C in the dark or in the light-activated preparations has been studied. Fluorescence lifetime in samples frozen in the light was longer than in samples frozen in the dark. For samples in 65% glycerol at λreg  = 335 nm and at 20 °C, the lifetime of components were as follows: τ1  ≈ 1.2 ns, τ2  ≈ 4...
October 23, 2018: Photosynthesis Research
After briefly describing my early collaborative work at the University of Allahabad, that had laid the foundation of my research life, I present here some of our research on photosynthesis at the University of Illinois at Urbana-Champaign, randomly selected from light absorption to NADP+ reduction in plants, algae, and cyanobacteria. These include the fact that (i) both the light reactions I and II are powered by light absorbed by chlorophyll (Chl) a of different spectral forms; (ii) light emission (fluorescence, delayed fluorescence, and thermoluminescence) by plants, algae, and cyanobacteria provides detailed information on these reactions and beyond; (iii) primary photochemistry in both the photosystems I (PS I) and II (PS II) occurs within a few picoseconds; and (iv) most importantly, bicarbonate plays a unique role on the electron acceptor side of PS II, specifically at the two-electron gate of PS II...
October 20, 2018: Photosynthesis Research
Rafael G Saer, Rebecca L Schultz, Robert E Blankenship
The trimeric nature of the Fenna-Matthews-Olson (FMO) protein antenna complex from green sulfur phototrophic bacteria was investigated. Mutations were introduced into the protein at positions 142 and 198, which were chosen to destabilize the intra-trimer salt bridges between adjacent monomers. Strains bearing the mutations R142L, R198L, or their combination, exhibited altered optical absorption spectra of purified membranes and fluoresced more intensely than the wild type. In particular, the introduction of the R142L mutation resulted in slower culture growth rates, as well as an FMO complex that was not able to be isolated in appreciable quantities, while the R198L mutation yielded an FMO complex with increased sensitivity to sodium thiocyanate and Triton X-100 treatments...
October 12, 2018: Photosynthesis Research
William A Cramer
Structure-function studies of the cytochrome b6 f complex, the central hetero-oligomeric membrane protein complex in the electron transport chain of oxygenic photosynthesis, which formed the basis for a high-resolution (2.5 Å) crystallographic solution of the complex, are described. Structure-function differences between the structure of subunits of the bc complexes, b6 f, and bc1 from mitochondria and photosynthetic bacteria, which are often assumed to function identically, are discussed. Major differences which suggest that quinone-dependent electron transport pathways can vary in b6 f and bc1 complexes are as follows: (a) an additional c-type heme, cn , and bound single copies of chlorophyll a and β-carotene in the b6 f complex; and (b) a cyclic electron transport pathway that encompasses the b6 f and PSI reaction center complexes...
October 11, 2018: Photosynthesis Research
Kumud B Mishra, Anamika Mishra, Jiří Kubásek, Otmar Urban, Arnd G Heyer, Govindjee
Cold acclimation modifies the photosynthetic machinery and enables plants to survive at sub-zero temperatures, whereas in warm habitats, many species suffer even at non-freezing temperatures. We have measured chlorophyll a fluorescence (ChlF) and CO2 assimilation to investigate the effects of cold acclimation, and of low temperatures, on a cold-sensitive Arabidopsis thaliana accession C24. Upon excitation with low intensity (40 µmol photons m- 2 s- 1 ) ~ 620 nm light, slow (minute range) ChlF transients, at ~ 22 °C, showed two waves in the SMT phase (S, semi steady-state; M, maximum; T, terminal steady-state), whereas CO2 assimilation showed a linear increase with time...
October 10, 2018: Photosynthesis Research
Binod Prasad, Wolfgang Lein, General Thiyam, Christoph Peter Lindenberger, Rainer Buchholz, Nithya Vadakedath
A mutated phytoene desaturase (pds) gene, pds-L504R, conferring resistance to the herbicide norflurazon has been reported as a dominant selectable marker for the genetic engineering of microalgae (Steinbrenner and Sandmann in Appl Environ Microbiol 72:7477-7484, 2006; Prasad et al. in Appl Microbiol Biotechnol 98(20):8629-8639, 2014). However, this mutated genomic clone harbors several introns and the entire expression cassette including its native promoter and terminator has a length > 5.6 kb, making it unsuitable as a standard selection marker...
October 1, 2018: Photosynthesis Research
Rachapudi Venkata Sreeharsha, Shalini Mudalkar, Debashree Sengupta, Divya K Unnikrishnan, Attipalli Ramachandra Reddy
In the current study, pigeonpea (Cajanus cajan L.), a promising legume food crop was assessed for its photosynthetic physiology, antioxidative system as well as C and N metabolism under elevated CO2 and combined drought stress (DS). Pigeonpea was grown in open top chambers under elevated CO2 (600 µmol mol-1 ) and ambient CO2 (390 ± 20 µmol mol-1 ) concentrations, later subjected to DS by complete water withholding. The DS plants were re-watered and recovered (R) to gain normal physiological growth and assessed the recoverable capacity in both elevated and ambient CO2 concentrations...
September 22, 2018: Photosynthesis Research
Anna Laura Erdei, Annamária Kósa, Béla Böddi
The effects of distinct UV-A and UV-B radiations were studied on etiolated pea (Pisum sativum L.) epicotyls. Emission spectra of the native protochlorophyll and protochlorophyllide forms were measured when epicotyls were excited with 360 or 300 nm light. The UV-A (360 nm) excited mainly the non-enzyme-bound monomers of protochlorophyll and protochlorophyllide and the UV-B (300 nm) excited preferentially the flash-photoactive protochlorophyllide complexes. These latter complexes converted into short- and long-wavelength chlorophyllide forms at 10-s illumination with both wavelength irradiations...
September 17, 2018: Photosynthesis Research
Ekaterina Petushkova, Sergei Iuzhakov, Anatoly Tsygankov
Pathways replenishing tricarboxylic acid cycle were divided into four major groups based on metabolite serving as source for oxaloacetic acid or other tricarboxylic acid cycle component synthesis. Using this metabolic map, the analysis of genetic potential for functioning of tricarboxylic acid cycle replenishment pathways was carried out for seven strains of purple non-sulfur bacterium Rhodopseudomonas palustris. The results varied from strain to strain. Published microarray data for phototrophic acetate cultures of Rps...
September 15, 2018: Photosynthesis Research
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