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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
Edward Laws, Alan Weidemann, George Hoch, Horatio Bannister, Robert S Knox, Govindjee
Tom Bannister (1930-2018) was an extraordinary person and a remarkably productive scientist. He began his career studying the basics of photochemistry, biophysics, and biology of photosynthetic pigments and later moved on to primary production of algae. His publications on modeling of primary production rates in aquatic systems are among the most widely cited in the field of phytoplankton ecology. His scientific enthusiasm was contagious, and his knowledge of photosynthesis and phytoplankton ecology enabled him to wisely mentor an impressive group of graduate students...
September 15, 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
Elsinraju Devadasu, Dinesh Kumar Chinthapalli, Nisha Chouhan, Sai Kiran Madireddi, Girish Kumar Rasineni, Prabhakar Sripadi, Rajagopal Subramanyam
The unicellular photosynthetic alga Chlamydomonas reinhardtii was propagated in iron deficiency medium and patterns of growth, photosynthetic efficiency, lipid accumulation, as well as the expression of lipid biosynthetic and photosynthesis-related proteins were analysed and compared with iron-sufficient growth conditions. As expected, the photosynthetic rate was reduced (maximally after 4 days of growth) as a result of increased non-photochemical quenching (NPQ). Surprisingly, the stress-response protein LHCSR3 was expressed in conditions of iron deficiency that cause NPQ induction...
September 14, 2018: Photosynthesis Research
Renate Scheibe
Plants depend on light energy for the generation of ATP and reductant as well as on supply of nutrients (inorganic C, N, and S compounds) to successfully produce biomass. Any excess of reducing power or lack of electron acceptors can lead to the formation of reactive oxygen species (ROS). Multiple systems are operating to avoid imbalances and subsequent oxidative stress by efficiently scavenging any formed ROS. Plants can sense an upcoming imbalance and correspondingly adapt to changed conditions not only by an increase of ROS scavengers, but also by using excess incoming light energy productively for assimilatory processes in actively metabolizing cells of growing leaves...
September 10, 2018: Photosynthesis Research
Jeremias C Zill, Marcel Kansy, Reimund Goss, A Alia, Christian Wilhelm, Jörg Matysik
Diatoms contribute about 20-25% to the global marine productivity and are successful autotrophic players in all aquatic ecosystems, which raises the question whether this performance is caused by differences in their photosynthetic apparatus. Photo-CIDNP MAS NMR presents a unique tool to obtain insights into the reaction centres of photosystems (PS), by selective enhancement of NMR signals from both, the electron donor and the primary electron acceptor molecules. Here, we present the first observation of the solid-state photo-CIDNP effect in the pennate diatoms...
September 7, 2018: Photosynthesis Research
Robert J Porra, Hugo Scheer
A recent publication (Esteban in New Phytol 217:341-342, 2018) describes how the use and citation of the assay of chlorophylls a and b extracted in aqueous 80% acetone by Arnon (Plant Physiol 2:1-15, 1949) is increasing, even in journals with high impact factors. This is a very disconcerting situation: the assay is outdated because it relies on the seriously under-estimated extinction coefficients of Mackinney (J Biol Chem 140:315-322, 1941), and the assay of chlorophylls is one of the most important, and much reported, procedures in studies of photosynthesis and related plant biological fields...
September 7, 2018: Photosynthesis Research
Long Vo Pham, Julian David Janna Olmos, Petko Chernev, Joanna Kargul, Johannes Messinger
Photosynthetic water oxidation is catalyzed by the oxygen-evolving complex (OEC) in photosystem II (PSII). This process is energetically driven by light-induced charge separation in the reaction center of PSII, which leads to a stepwise accumulation of oxidizing equivalents in the OEC (Si states, i = 0-4) resulting in O2 evolution after each fourth flash, and to the reduction of plastoquinone to plastoquinol on the acceptor side of PSII. However, the Si -state advancement is not perfect, which according to the Kok model is described by miss-hits (misses)...
September 6, 2018: Photosynthesis Research
Bobba Sunil, Deepak Saini, Ramesh B Bapatla, Vetcha Aswani, Agepati S Raghavendra
Optimization of photosynthetic performance and protection against abiotic stress are essential to sustain plant growth. Photorespiratory metabolism can help plants to adapt to abiotic stress. The beneficial role of photorespiration under abiotic stress is further strengthened by cyclic electron flow (CEF) and alternative oxidase (AOX) pathways. We have attempted to critically assess the literature on the responses of these three phenomena-photorespiration, CEF and AOX, to different stress situations. We emphasize that photorespiration is the key player to protect photosynthesis and upregulates CEF as well as AOX...
September 5, 2018: Photosynthesis Research
Ryo Nagao, Yoshifumi Ueno, Fusamichi Akita, Takehiro Suzuki, Naoshi Dohmae, Seiji Akimoto, Jian-Ren Shen
Diatoms are dominant phytoplankton in aquatic environments and have unique light-harvesting apparatus, fucoxanthin chlorophyll a/c-binding protein (FCP). Diatom photosystem I (PSI) interacts with specific FCPs (FCPI); however, it remains unclear how PSI cores receive excitation energy from FCPI. To analyze the energy transfer dynamics, it is necessary to isolate both PSI cores and PSI-FCPI complexes. In this study, we prepared three PSI complexes, which are PSI-FCPI membrane fragments, detergent-solubilized PSI-FCPI supercomplexes and PSI core-like complexes, from the marine centric diatom, Chaetoceros gracilis, and examined their biochemical properties...
September 5, 2018: Photosynthesis Research
Misato Teramura, Jiro Harada, Hitoshi Tamiaki
Unique light-harvesting antennas in the green sulfur bacterium Chlorobaculum tepidum, called chlorosomes, consist of self-aggregates of bacteriochlorophyll (BChl) c. In the biosynthesis of BChl c, BciC demethoxycarbonylase removes the C132 -methoxycarbonyl group to facilitate the self-aggregation of BChl c. We previously reported the in vitro BciC-enzymatic reactions and discussed the function of this enzyme in the biosynthesis of BChl c. This study aims to examine the substrate specificity of BciC in detail using several semi-synthetic (bacterio)chlorophyll derivatives...
September 4, 2018: Photosynthesis Research
C H Lucas Patty, Freek Ariese, Wybren Jan Buma, Inge Loes Ten Kate, Rob J M van Spanning, Frans Snik
Photosynthetic eukaryotes show a remarkable variability in photosynthesis, including large differences in light-harvesting proteins and pigment composition. In vivo circular spectropolarimetry enables us to probe the molecular architecture of photosynthesis in a non-invasive and non-destructive way and, as such, can offer a wealth of physiological and structural information. In the present study, we have measured the circular polarizance of several multicellular green, red, and brown algae and higher plants, which show large variations in circular spectropolarimetric signals with differences in both spectral shape and magnitude...
August 23, 2018: Photosynthesis Research
Emelie Lindquist, Henrik Aronsson
Photosynthesis is a well-known process that has been intensively investigated, but less is known about the biogenesis of the thylakoid membrane that harbors the photosynthetic machinery. Thylakoid membranes are constituted by several components, the major ones being proteins and lipids. However, neither of these two are produced in the thylakoid membranes themselves but are targeted there by different mechanisms. The interior of the chloroplast, the stroma, is an aqueous compartment that prevents spontaneous transport of single lipids and/or membrane proteins due to their hydrophobicities...
August 16, 2018: Photosynthesis Research
Christopher Paul New, Qianqian Ma, Carole Dabney-Smith
Thylakoids are complex sub-organellar membrane systems whose role in photosynthesis makes them critical to life. Thylakoids require the coordinated expression of both nuclear- and plastid-encoded proteins to allow rapid response to changing environmental conditions. Transport of cytoplasmically synthesized proteins to thylakoids or the thylakoid lumen is complex; the process involves transport across up to three membrane systems with routing through three aqueous compartments. Protein transport in thylakoids is accomplished by conserved ancestral prokaryotic plasma membrane translocases containing novel adaptations for the sub-organellar location...
August 12, 2018: Photosynthesis Research
Adrien Jacotot, Cyril Marchand, Simon Gensous, Michel Allenbach
In this study, we examined interactive effects of elevated atmospheric CO2 , concentrations, and increased tidal flooding on two mangroves species, Avicennia marina and Rhizophora stylosa. Leaf gas-exchange parameters (photosynthesis, transpiration rates, water-use efficiency, stomatal conductance, and dark respiration rates) were measured monthly on more than 1000 two-year-old seedlings grown in greenhouses for 1 year. In addition, stomatal density and light curve responses were determined at the end of the experiment...
August 9, 2018: Photosynthesis Research
Wen Min Huang, Hui Shao, Si Ning Zhou, Qin Zhou, Wen Long Fu, Ting Zhang, Hong Sheng Jiang, Wei Li, Brigitte Gontero, Stephen C Maberly
The freshwater macrophyte, Ottelia alismoides, is a bicarbonate user performing C4 photosynthesis in the light, and crassulacean acid metabolism (CAM) when acclimated to low CO2 . The regulation of the three mechanisms by CO2 concentration was studied in juvenile and mature leaves. For mature leaves, the ratios of phosphoenolpyruvate carboxylase (PEPC) to ribulose-bisphosphate carboxylase/oxygenase (Rubisco) are in the range of that of C4 plants regardless of CO2 concentration (1.5-2.5 at low CO2 , 1.8-3.4 at high CO2 )...
August 4, 2018: Photosynthesis Research
Alexander Watson-Lazowski, Alexie Papanicolaou, Robert Sharwood, Oula Ghannoum
Expanding knowledge of the C4 photosynthetic pathway can provide key information to aid biological improvements to crop photosynthesis and yield. While the C4 NADP-ME pathway is well characterised, there is increasing agricultural and bioengineering interest in the comparably understudied NAD-ME and PEPCK pathways. Within this study, a systematic identification of key differences across species has allowed us to investigate the evolution of C4 -recruited genes in one C3 and eleven C4 grasses (Poaceae) spanning two independent origins of C4 photosynthesis...
August 4, 2018: Photosynthesis Research
T K Antal, A Maslakov, O V Yakovleva, T E Krendeleva, G Yu Riznichenko, A B Rubin
A model of primary photosynthetic reactions in the thylakoid membrane was developed and its validity was tested by simulating three types of experimental kinetic curves: (1) the light-induced chlorophyll a fluorescence rise (OJIP transients) reflecting the stepwise transition of the photosynthetic electron transport chain from the oxidized to the fully reduced state; (2) the dark relaxation of the flash-induced fluorescence yield attributed to the QA - oxidation kinetics in PSII; and (3) the light-induced absorbance changes near 820 or 705 nm assigned to the redox transitions of P700 in PSI...
July 30, 2018: Photosynthesis Research
Wei Huang, Marjaana Suorsa, Shi-Bao Zhang
In chloroplast, proton motive force (pmf) is critical for ATP synthesis and photoprotection. To prevent photoinhibition of photosynthetic apparatus, proton gradient (ΔpH) across the thylakoid membranes needs to be built up to minimize the production of reactive oxygen species (ROS) in thylakoid membranes. However, the regulation of thylakoid pmf in immature leaves is little known. In this study, we compared photosynthetic electron sinks, P700 redox state, non-photochemical quenching (NPQ), and electrochromic shift (ECS) signal in immature and mature leaves of a cultivar of Camellia...
July 28, 2018: Photosynthesis Research
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