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Lijie Li, Wanrong Gu, Jing Li, Congfeng Li, Tenglong Xie, Danyang Qu, Yao Meng, Caifeng Li, Shi Wei
Drought stress (DS) is a major environmental factor limiting plant growth and crop productivity worldwide. It has been established that exogenous spermidine (Spd) stimulates plant tolerance to DS. The effects of exogenous Spd on plant growth, photosynthetic performance, and chloroplast ultrastructure as well as changes in endogenous polyamines (PAs) and phytohormones were investigate in DS-resistant (Xianyu 335) and DS-sensitive (Fenghe 1) maize seedlings under well-watered and DS treatments. Exogenous Spd alleviated the stress-induced reduction in growth, photosynthetic pigment content, photosynthesis rate (Pn ) and photochemical quenching (qP ) parameters, including the maximum photochemistry efficiency of photosystem II (PSII) (Fv /Fm ), PSII operating efficiency (ФPSII), and qP coefficient...
May 15, 2018: Plant Physiology and Biochemistry: PPB
Daisuke Takagi, Kentaro Ifuku, Taishi Nishimura, Chikahiro Miyake
The light reactions of photosynthesis are known to comprise both linear and cyclic electron flow in order to convert light energy into chemical energy in the form of NADPH and ATP. Antimycin A (AA) has been proposed as an inhibitor of ferredoxin-dependent cyclic electron flow around photosystem I (CEF-PSI) in photosynthesis research. However, its precise inhibitory mechanism and target site had not been elucidated yet. Here we show that AA inhibits the cyclic (alternative) electron flow via cytochrome b559 (Cyt b559 ) within photosystem II (CEF-PSII)...
May 22, 2018: Photosynthesis Research
Georgios Chararalambidis, Syamal Das, Adelais Trapali, Annamaria Quaranta, Maylis Orio, Zakaria Halime, Pierre Fertey, Régis Guillot, Athanassios Coutsolelos, Winfried Leibl, Ally Aukauloo, Marie Sircoglou
In this report, we investigate on a biomimetic model of a H-bonded TyrZ/His190 pair covalently attached to a porphyrin sensitizer. Laser flash photolysis in presence of an external electron acceptor reveals the need of water molecules to unlock the light-induced oxidation of the phenol through an intramolecular pathway. Kinetics monitoring encompasses two fast phases with distinct spectral properties. The first phase is related to one-electron transfer from the phenol to the porphyrin radical cation coupled with a domino two-proton transfer leading to the ejection of a proton from the imidazole-phenol pair...
May 22, 2018: Angewandte Chemie
Keisuke Kawashima, Hiroshi Ishikita
We report redox potentials ( E m ) for one-electron reduction for all chlorophylls in the two electron-transfer branches of water-oxidizing enzyme photosystem II (PSII), photosystem I (PSI), and purple bacterial photosynthetic reaction centers (PbRC). In PSI, E m values for the accessory chlorophylls were similar in both electron-transfer branches. In PbRC, the corresponding E m value was 170 mV less negative in the active L-branch (BL ) than in the inactive M-branch (BM ), favoring BL ˙- formation. This contrasted with the corresponding chlorophylls, ChlD1 and ChlD2 , in PSII, where E m (ChlD1 ) was 120 mV more negative than E m (ChlD2 ), implying that to rationalize electron transfer in the D1-branch, ChlD1 would need to serve as the primary electron donor...
May 7, 2018: Chemical Science
Makoto Nakamura, Alain Boussac, Miwa Sugiura
Cytb559 in Photosystem II is a heterodimeric b-type cytochrome. The subunits, PsbE and PsbF, consist each in a membrane α-helix. Mutants were previously designed and studied in Thermosynechococcus elongatus (Sugiura et al., Biochim Biophys Acta 1847:276-285, 2015) either in which an axial histidine ligand of the haem-iron was substituted for a methionine, the PsbE/H23M mutant in which the haem was lacking, or in which the haem environment was modified, the PsbE/Y19F and PsbE/T26P mutants. All these mutants remained active showing that the haem has no structural role provided that PsbE and PsbF subunits are present...
May 19, 2018: Photosynthesis Research
Matthias Gilbert, Hanno Bährs, Christian E W Steinberg, Christian Wilhelm
Humic substances (HSs) can influence the growth and composition of freshwater phytoplankton assemblage. Since HSs contain many phenolic and quinonic moieties and cause growth reductions in eco-physiological field experiments, HSs are considered photosystem II herbicides. To test this specific mode of action in vivo and in vitro, respectively, we used intact cells of the green alga Desmodesmus armatus, as well as thylakoids isolated from spinach (Spinacia oleracea) as a model system for the green algal chloroplast...
May 18, 2018: Photosynthesis Research
Shuzhen Lv, Kangyao Zhang, Yongyi Zeng, Dianping Tang
A new double photosystems-based 'Z-scheme' photoelectrochemical (PEC) sensing platform is designed for ultrasensitive detection of prostate-specific antigen (PSA) by coupling with three-dimensional (3D) DNA walker. Two photosystems consist of CdS quantum dots (photosystem I; PS I) and BiVO4 photoactive materials (photosystem II; PS II), whereas gold nanoparticles (AuNPs) photodeposited on high-active {010} facets of BiVO4 are used as the electron mediators to promote electron transfer from conduction band (CB) of PS II to valence band (VB) of PS I...
May 18, 2018: Analytical Chemistry
Mateusz Dyda, Iwona Wąsek, Mirosław Tyrka, Maria Wędzony, Magdalena Szechyńska-Hebda
Microdochium nivale is a fungal pathogen that causes yield losses of cereals during winter. Cold hardening under light conditions induces genotype-dependent resistance of a plant to infection. We aim to show how photosystem II (PSII) regulation contributes to plant resistance. Using mapping population of triticale doubled haploid lines, three M. nivale strains and different infection assays, we demonstrate that plants that maintain a higher maximum quantum efficiency of PSII show less leaf damage upon infection...
May 17, 2018: Physiologia Plantarum
Rong Zhou, Lingpeng Kong, Zhen Wu, Eva Rosenqvist, Yinlei Wang, Liping Zhao, Tongmin Zhao, Carl-Otto Ottosen
In nature, crops encounter a combination of abiotic stresses that severely limit yield. Our aim was to dynamically expose the changes of tomatoes' physiological parameters to drought, heat and their combination and thereby clarify the relationship between the responses to single and combined stress. We studied the effect of single and combined drought and heat stresses on the shoot and root of two tomato cultivars (Sufen No.14 as CV1; Jinlingmeiyu as CV2). After being exposed to combined stress for six days, the dry weight of shoot and root significantly decreased...
May 17, 2018: Physiologia Plantarum
Fangyuan Zhao, Steffen Hardt, Volker Hartmann, Huijie Zhang, Marc M Nowaczyk, Matthias Rögner, Nicolas Plumeré, Wolfgang Schuhmann, Felipe Conzuelo
Interfacing photosynthetic proteins specifically photosystem 1 (PS1) with electrodes enables light-induced charge separation processes for powering semiartificial photobiodevices with, however, limited long-term stability. Here, we present the in-depth evaluation of a PS1/Os-complex-modified redox polymer-based biocathode by means of scanning photoelectrochemical microscopy. Focalized local illumination of the bioelectrode and concomitant collection of H2 O2 at the closely positioned microelectrode provide evidence for the formation of partially reduced oxygen species under light conditions...
May 17, 2018: Nature Communications
Lucilla Taddei, Volha Chukhutsina, Bernard Lepetit, Giulio R Stella, Roberto Bassi, Herbert van Amerongen, Jean-Pierre Bouly, Marianne Jaubert, Giovanni Finazzi, Angela Falciatore
Marine diatoms are prominent phytoplankton organisms, optimally performing photosynthesis in extremely variable environments. Diatoms possess a strong ability to dissipate excess absorbed energy as heat via non-photochemical quenching (NPQ). This process relies on changes in carotenoid pigment composition (xanthophyll cycle) and on specific members of the light-harvesting complex (LHC) family specialized in photoprotection (LHCX), which potentially act as NPQ effectors. However, the link between light stress, NPQ, and the existence of different LHCX isoforms is not understood in these organisms...
May 17, 2018: Plant Physiology
Vítor Gabriel Ambrosini, Daniel José Rosa, George Wellington Bastos de Melo, Jovani Zalamena, Cesar Cella, Daniela Guimarães Simão, Leandro Souza da Silva, Henrique Pessoa Dos Santos, Moreno Toselli, Tadeu Luis Tiecher, Gustavo Brunetto
High copper (Cu) soil contents, due to the continuous vineyard application of Cu fungicides throughout the years, may impair the growth of the shoot and modify the structure of the root system. The current study aimed to investigate the threshold levels of available Cu in the soil causing toxicity effects in young grapevine plants of 'Red Niagara' cultivated in clay soils. Grapevine plantlets were cultivated in pots containing vineyard devoted soils with increasing contents of available Cu (25, 80, 100 and 165 mg kg-1 ), for 53 days...
May 8, 2018: Plant Physiology and Biochemistry: PPB
Jianan Zhu, Zhiming Yu, Liyan He, Xihua Cao, Shuya Liu, Xiuxian Song
The data and experiences in mitigating harmful algal blooms (HABs) by modified clay (MC) show that a bloom does not continue after the dispersal of the MC, even though the density of the residual cells in the water is still high, at 20-30% of the initial cell density. This interesting phenomenon indicates that in addition to flocculation, MC has an additional control mechanism. Here, transcriptome sequencing technology was used to study the molecular mechanism of MC in controlling HABs. In residual cells treated with MC, the photosynthetic light reaction was the most affected physiological process...
May 16, 2018: Environmental Science & Technology
Hermann Bothe, Thomas Happe, Simon Trebst, Matthias Rögner
The life and work of Achim Trebst (1929-2017) was dedicated to photosynthesis, involving a wide span of seminal contributions which cumulated in more than five decades of active research: Major topics include the separation of light and dark phases in photosynthesis, the elucidation of photosynthesis by the use of inhibitors, the identification of the three-dimensional structure of photosystem II and its degradation, and an explanation of singlet oxygen formation. For this tribute, which has been initiated by Govindjee, twenty-two personal tributes by former coworkers, scientific friends, and his family have been compiled and combined with an introduction tracing the different stages of Achim Trebst's scientific life...
May 16, 2018: Photosynthesis Research
Anastasia Petrova, Mahir Mamedov, Boris Ivanov, Alexey Semenov, Marina Kozuleva
The peculiarities of interaction of cyanobacterial photosystem I with redox mediators 2,6-dichlorophenolindophenol (DCPIP) and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) were investigated. The higher donor efficiency of the reduced DCPIP form was demonstrated. The oxidized form of DCPIP was shown to be an efficient electron acceptor for terminal iron-sulfur cluster of photosystem I. Likewise methyl viologen, after one-electron reduction, DCPIP transfers an electron to the molecular oxygen. These results were discussed in terms of influence of these interactions on photosystem I reactions with the molecular oxygen and natural electron acceptors...
May 16, 2018: Photosynthesis Research
Anderson Kikuchi Calzavara, Pedro Henrique Godoy Paiva, Lorrant Cavanha Gabriel, André Luiz Martinez de Oliveira, Karina Milani, Halley Caixeta Oliveira, Edmilson Bianchini, José Antonio Pimenta, Maria Cristina Neves de Oliveira, Jaqueline Dias-Pereira, Renata Stolf-Moreira
Despite the great diversity of plant growth-promoting bacteria (PGPB) with potential to partially replace the use of N-fertilizers in agriculture, few PGPB are explored for the production of commercial inoculants, reinforcing the importance of identifying positive plant-bacteria interactions. Aiming to better understand the influence of PGPB inoculation in plant development, two PGPB species with distant phylogenetic relationship were inoculated in maize. Maize seeds were inoculated with Bacillus sp. or Azospirillum brasilense...
May 15, 2018: Plant Biology
Shinya Wada, Yuji Suzuki, Daisuke Takagi, Chikahiro Miyake, Amane Makino
Under CO2 -limited conditions such as during stomatal closure, photorespiration is suggested to act as a sink for excess light energy and protect photosystem I (PSI) by oxidizing its reaction center chlorophyll P700. In this study, this issue was directly examined with rice (Oryza sativa L.) plants via genetic manipulation of the amount of Rubisco, which can be a limiting factor for photorespiration. At low [CO2 ] of 5 Pa that mimicked stomatal closure condition, the activity of photorespiration in transgenic plants with decreased Rubisco content (RBCS-antisense plants) markedly decreased, whereas the activity in transgenic plants with overproduction of Rubisco (RBCS-sense plants) was similar to that in wild-type plants...
May 14, 2018: Photosynthesis Research
Weiping Shi, Jingye Cheng, Xiaojie Wen, Jixiang Wang, Guanyan Shi, Jiayan Yao, Liyuan Hou, Qian Sun, Peng Xiang, Xiangyang Yuan, Shuqi Dong, Pingyi Guo, Jie Guo
Drought stress is one of the most important abiotic factors limiting crop productivity. A better understanding of the effects of drought on millet ( Setaria italica L.) production, a model crop for studying drought tolerance, and the underlying molecular mechanisms responsible for drought stress responses is vital to improvement of agricultural production. In this study, we exposed the drought resistant F1 hybrid, M79, and its parental lines E1 and H1 to drought stress. Subsequent physiological analysis demonstrated that M79 showed higher photosynthetic energy conversion efficiency and drought tolerance than its parents...
2018: PeerJ
Hideshi Ooka, Kazuhito Hashimoto, Ryuhei Nakamura
Understanding the design strategy of photosynthetic and respiratory enzymes is important to develop efficient artificial catalysts for oxygen evolution and reduction reactions. Here, based on a bioinformatic analysis of cyanobacterial oxygen evolution and reduction enzymes (photosystem II: PS II and cytochrome c oxidase: COX, respectively), the gene encoding the catalytic D1 subunit of PS II was found to be expressed individually across 38 phylogenetically diverse strains, which is in contrast to the operon structure of the genes encoding major COX subunits...
May 14, 2018: Molecular Informatics
Mahshid Samadani, David Dewez
In this study, the accumulation and toxicity effect of 1-7 μM of Hg was determined during 24-72 h on two strains of Chlamydomonas reinhardtii, CC-125 and CC-503 as a cell wall-deficient mutant, by monitoring the growth rate and the maximum quantum yield of Photosystem II. In addition, the level of extracytoplasmic polyphosphates (polyP related to the cell wall) was determined to understand the polyP physiological role in Hg-treated algal cells. The results showed that the polyP level was higher in the strain CC-125 compared to CC-503...
May 10, 2018: Environmental Pollution
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