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Photosynthesis Research

Simona Streckaite, Zdenko Gardian, Fei Li, Andrew A Pascal, Radek Litvin, Bruno Robert, Manuel J Llansola-Portoles
The soil chromophyte alga Xanthonema (X.) debile contains only non-carbonyl carotenoids and Chl-a. X. debile has an antenna system denoted Xanthophyte light-harvesting complex (XLH) that contains the carotenoids diadinoxanthin, heteroxanthin, and vaucheriaxanthin. The XLH pigment stoichiometry was calculated by chromatographic techniques and the pigment-binding structure studied by resonance Raman spectroscopy. The pigment ratio obtained by HPLC was found to be close to 8:1:2:1 Chl-a:heteroxanthin:diadinoxanthin:vaucheriaxanthin...
July 13, 2018: Photosynthesis Research
Akanksha Mhatre, Smita Patil, Akanksha Agarwal, Reena Pandit, Arvind M Lali
Ulva lactuca is regarded as a prospective energy crop for biorefinery owing to its affluent biochemical composition and high growth rate. In fast-growing macroalgae, biomass development strictly depends on external nitrogen pools. Additionally, nitrogen uptake rates and photosynthetic pigment content vary with type of nitrogen source and light conditions. However, the combined influence of nitrogen source and light intensity on photosynthesis is not widely studied. In present study, pale green phenotype of U...
July 9, 2018: Photosynthesis Research
Sonal Mathur, Rupal Singh Tomar, Anjana Jajoo
Drought stress (DS) is amongst one of the abiotic factors affecting plant growth by limiting productivity of crops by inhibiting photosynthesis. Damage due to DS and its protection by Arbuscular Mycorrhizal fungi (AMF) was studied on photosynthetic apparatus of wheat (Triticum aestivum) plants in pot experiments. DS was maintained by limiting irrigation to the drought stressed (DS) and AMF + DS plants. Relative Water content (RWC) was measured for leaf as well as soil to ensure drought conditions. DS plants had minimum RWC for both leaf and soil...
July 7, 2018: Photosynthesis Research
Srilatha Nama, Sai Kiran Madireddi, Ranay Mohan Yadav, Rajagopal Subramanyam
Light is essential for all photosynthetic organisms while an excess of it can lead to damage mainly the photosystems of the thylakoid membrane. In this study, we have grown Chlamydomonas reinhardtii cells in different intensities of high light to understand the photosynthetic process with reference to thylakoid membrane organization during its acclimation process. We observed, the cells acclimatized to long-term response to high light intensities of 500 and 1000 µmol m-2  s-1 with faster growth and more biomass production when compared to cells at 50 µmol m-2  s-1 light intensity...
July 7, 2018: Photosynthesis Research
Carolina Salazar-Parra, Iker Aranjuelo, Inmaculada Pascual, Jone Aguirreolea, Manuel Sánchez-Díaz, Juan José Irigoyen, José Luis Araus, Fermín Morales
Foreseen climate change is expected to impact on grape composition, both sugar and pigment content. We tested the hypothesis that interactions between main factors associated with climate change (elevated CO2 , elevated temperature, and water deficit) decouple sugars and anthocyanins, and explored the possible involvement of vegetative area, photosynthesis, and grape C uploading on the decoupling. Tempranillo grapevine fruit-bearing cuttings were exposed to CO2 (700 vs. 400 ppm), temperature (ambient vs. + 4 °C), and irrigation levels (partial vs...
July 6, 2018: Photosynthesis Research
Rafał Białek, David J K Swainsbury, Maciej Wiesner, Michael R Jones, Krzysztof Gibasiewicz
As one of a number of new technologies for the harnessing of solar energy, there is interest in the development of photoelectrochemical cells based on reaction centres (RCs) from photosynthetic organisms such as the bacterium Rhodobacter (Rba.) sphaeroides. The cell architecture explored in this report is similar to that of a dye-sensitized solar cell but with delivery of electrons to a mesoporous layer of TiO2 by natural pigment-protein complexes rather than an artificial dye. Rba. sphaeroides RCs were bound to the deposited TiO2 via an engineered extramembrane peptide tag...
July 3, 2018: Photosynthesis Research
Evan LaBrant, Allison C Barnes, Rebecca L Roston
Photosynthetic membranes provide much of the usable energy for life on earth. To produce photosynthetic membrane lipids, multiple transport steps are required, including fatty acid export from the chloroplast stroma to the endoplasmic reticulum, and lipid transport from the endoplasmic reticulum to the chloroplast envelope membranes. Transport of hydrophobic molecules through aqueous space is energetically unfavorable and must be catalyzed by dedicated enzymes, frequently on specialized membrane structures...
June 30, 2018: Photosynthesis Research
Xiaoyi Zhu, Liang Zhang, Chen Kuang, Yan Guo, Chunqian Huang, Linbin Deng, Xingchao Sun, Gaomiao Zhan, Zhiyong Hu, Hanzhong Wang, Wei Hua
In plants, green non-foliar organs are able to perform photosynthesis just as leaves do, and the seed-enclosing pod acts as an essential photosynthetic organ in legume and Brassica species. To date, the contribution of pod photosynthesis to seed yield and related components still remains largely unexplored, and in Arabidopsis thaliana, the photosynthetic activity of the silique (pod) is unknown. In this study, an Arabidopsis glk1/glk2 mutant defective in both leaf and silique photosynthesis was used to create tissue-specific functional complementation lines...
June 29, 2018: Photosynthesis Research
Junji Uchiyama, Ayako Itagaki, Haruna Ishikawa, Yu Tanaka, Hidetaka Kohga, Ayami Nakahara, Akiko Imaida, Hiroko Tahara, Hisataka Ohta
Over 50 ATP-binding cassette (ABC) transporter-related genes are detected in the Synechocystis sp. PCC 6803 genome by genome sequence analysis. Deletion mutants of other substrate-unknown ABC transporter genes were screened for their acid stress sensitivities in a low-pH medium to identify ABC transporters involved in acid resistance. We found that a mutant of sll1180 encoding proteins with homology to HlyB in Escherichia coli (E.coli) is more sensitive to acid stress than wild-type (WT) cells and analyzed the abundance of expression of the genes in WT cells under acid stress condition by quantitative real-time reverse transcriptase-polymerase chain reaction...
June 29, 2018: Photosynthesis Research
Dominik Ziehe, Beatrix Dünschede, Danja Schünemann
The light-harvesting chlorophyll a/b binding proteins (LHCP) belong to a large family of membrane proteins. They form the antenna complexes of photosystem I and II and function in light absorption and transfer of the excitation energy to the photosystems. As nuclear-encoded proteins, the LHCPs are imported into the chloroplast and further targeted to their final destination-the thylakoid membrane. Due to their hydrophobicity, the formation of the so-called 'transit complex' in the stroma is important to prevent their aggregation in this aqueous environment...
June 28, 2018: Photosynthesis Research
Donna E Fernandez
Chloroplasts inherited systems and strategies for protein targeting, translocation, and integration from their cyanobacterial ancestor. Unlike cyanobacteria however, chloroplasts in green algae and plants contain two distinct SEC translocase/integrase systems: the SEC1 system in the thylakoid membrane and the SEC2 system in the inner envelope membrane. This review summarizes the mode of action of SEC translocases, identification of components of the SEC2 system, evolutionary history of SCY and SECA genes, and previous work on the co- and post-translational targeting of lumenal and thylakoid membrane proteins to the SEC1 system...
June 27, 2018: Photosynthesis Research
Mayank Sharma, Bationa Bennewitz, Ralf Bernd Klösgen
Dual targeting of a nuclearly encoded protein into two different cell organelles is an exceptional event in eukaryotic cells. Yet, the frequency of such dual targeting is remarkably high in case of mitochondria and chloroplasts, the two endosymbiotic organelles of plant cells. In most instances, it is mediated by "ambiguous" transit peptides, which recognize both organelles as the target. A number of different approaches including in silico, in organello as well as both transient and stable in vivo assays are established to determine the targeting specificity of such transit peptides...
June 26, 2018: Photosynthesis Research
Bettina Bölter
Chloroplasts are the characteristic endosymbiotic organelles of plant cells which during the course of evolution lost most of their genetic information to the nucleus. Thus, they critically depend on the host cell for allocation of nearly their complete protein supply. This includes gene expression, translation, protein targeting, and transport-all of which need to be tightly regulated and perfectly coordinated to accommodate the cells' needs. To this end, multiple signaling pathways have been implemented that interchange information between the different cellular compartments...
June 26, 2018: Photosynthesis Research
Chiung-Chih Chu, Hsou-Min Li
The plastid proteome changes according to developmental stages. Accruing evidence shows that, in addition to transcriptional and translational controls, preprotein import into plastids is also part of the process regulating plastid proteomes. Different preproteins have distinct preferences for plastids of different tissues. Preproteins are also divided into at least three age-selective groups based on their import preference for chloroplasts of different ages. Both tissue and age selectivity are determined by the transit peptide of each preprotein, and a transit-peptide motif for older-chloroplast preference has been identified...
June 25, 2018: Photosynthesis Research
Shuntaro Machida, Iwane Suzuki
Recently, microalgae have attracted attention as sources of biomass energy. However, fatty acids from the microalgae are mainly unsaturated and show low stability in oxygenated environments, due to oxidation of the double bonds. The branched-chain fatty acid, 10-methyl stearic acid, is synthesized from oleic acid in certain bacteria; the fatty acid is saturated, but melting point is low. Thus, it is stable in the presence of oxygen and is highly fluid. We previously demonstrated that BfaA and BfaB in Mycobacterium chlorophenolicum are involved in the synthesis of 10-methyl stearic acid from oleic acid...
June 25, 2018: Photosynthesis Research
Priscila Herrera-Salgado, Lourdes E Leyva-Castillo, Emmanuel Ríos-Castro, Carlos Gómez-Lojero
Synechococcus ATCC 29403 (PCC 7335) is a unicellular cyanobacterium isolated from Puerto Peñasco, Sonora Mexico. This cyanobacterium performs complementary chromatic acclimation (CCA), far-red light photoacclimation (FaRLiP), and nitrogen fixation. The Synechococcus PCC 7335 genome contains at least 31 genes for proteins of the phycobilisome (PBS). Nine constitutive genes were expressed when cells were grown under white or red lights and the resulting proteins were identified by mass spectrometry in isolated PBS...
June 25, 2018: Photosynthesis Research
Frédéric Partensky, Daniella Mella-Flores, Christophe Six, Laurence Garczarek, Mirjam Czjzek, Dominique Marie, Eva Kotabová, Kristina Felcmanová, Ondřej Prášil
The extrinsic PsbU and PsbV proteins are known to play a critical role in stabilizing the Mn4 CaO5 cluster of the PSII oxygen-evolving complex (OEC). However, most isolates of the marine cyanobacterium Prochlorococcus naturally miss these proteins, even though they have kept the main OEC protein, PsbO. A structural homology model of the PSII of such a natural deletion mutant strain (P. marinus MED4) did not reveal any obvious compensation mechanism for this lack. To assess the physiological consequences of this unusual OEC, we compared oxygen evolution between Prochlorococcus strains missing psbU and psbV (PCC 9511 and SS120) and two marine strains possessing these genes (Prochlorococcus sp...
June 25, 2018: Photosynthesis Research
Eugene A Lysenko, Alexander A Klaus, Alexander V Kartashov, Victor V Kusnetsov
Plant growth and photosynthetic activity are usually inhibited due to the overall action of Cd on a whole organism, though few cadmium cations can invade chloroplasts in vivo. We found that in vivo, the major portion of Cd in barley chloroplasts is located in the thylakoids (80%), and the minor portion is in the stroma (20%). Therefore, the electron-transport chain in the thylakoids would be the likely target for direct Cd action in vivo. In vitro, we found the distribution of Cd to be shifted to the stroma (40-60%)...
June 21, 2018: Photosynthesis Research
Michael A Benkov, Anton M Yatsenko, Alexander N Tikhonov
In this work, we have compared photosynthetic characteristics of photosystem II (PSII) in Tradescantia leaves of two contrasting ecotypes grown under the low light (LL) and high light (HL) regimes during their entire growth period. Plants of the same genus, T. fluminensis (shade-tolerant) and T. sillamontana (sun-resistant), were cultivated at 50-125 µmol photons m-2  s-1 (LL) or at 875-1000 µmol photons m-2  s-1 (HL). Analyses of intrinsic PSII efficiency was based on measurements of fast chlorophyll (Chl) a fluorescence kinetics (the OJIP test)...
June 20, 2018: Photosynthesis Research
Ryoichi Sato, Rinya Kawashima, Mai Duy Luu Trinh, Masahiro Nakano, Takeharu Nagai, Shinji Masuda
The proton motive force (PMF) across the chloroplast thylakoid membrane that is generated by electron transport during photosynthesis is the driving force for ATP synthesis in plants. The PMF mainly arises from the oxidation of water in photosystem II and from electron transfer within the cytochrome b6 f complex. There are two electron transfer pathways related to PMF formation: linear electron flow and cyclic electron flow. Proton gradient regulation 5 (PGR5) is a major component of the cyclic electron flow pathway, and the Arabidopsis pgr5 mutant shows a substantial reduction in the PMF...
June 18, 2018: Photosynthesis Research
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