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Tommaso Michele Moles, Antonio Pompeiano, Thais Huarancca Reyes, Andrea Scartazza, Lorenzo Guglielminetti
Landraces represent an important part of the biodiversity well-adapted under limiting environmental conditions. We investigated the response of two Southern Italy tomato landraces, the well-known San Marzano (our commercial standard) and a local accession called "Ciettaicale", to different levels of sodium chloride in water irrigation (from 0 up to 600 mM) for a short-time exposure (one week). The combination of the chlorophyll a fluorescence and gas exchange analyses suggested that Ciettaicale maintained a higher efficiency of photosystem II (PSII) photochemistry and CO2 utilization at high salinity concentrations than San Marzano...
October 12, 2016: Plant Physiology and Biochemistry: PPB
Wei Huang, Ying-Jie Yang, Hong Hu, Shi-Bao Zhang
Low temperature associated with high light can induce photoinhibition of photosystem I (PSI) and photosystem II (PSII). However, the photosynthetic electron flow and specific photoprotective responses in alpine evergreen broad-leaf plants in winter is unclear. We analyzed seasonal changes in PSI and PSII activities, and energy quenching in PSI and PSII in three alpine broad-leaf tree species, Quercus guyavifolia (Fagaceae), Rhododendron decorum (Ericaceae), Euonymus tingens (Celastraceae). In winter, PSII activity remained stable in Q...
October 13, 2016: Journal of Photochemistry and Photobiology. B, Biology
Dany P Moualeu-Ngangue, Tsu-Wei Chen, Hartmut Stützel
Gas exchange (GE) and chlorophyll fluorescence (CF) measurements are widely used to noninvasively study photosynthetic parameters, for example the rates of maximum Rubisco carboxylation (Vcmax ), electron transport rate (J), daytime respiration (Rd ) and mesophyll conductance (gm ). Existing methods for fitting GE data (net assimilation rate-intercellular space CO2 concentration (A-Ci ) curve) are based on two assumptions: gm is unvaried with CO2 concentration in the intercellular space (Ci ); and light absorption (α) and the proportion of quanta absorbed by photosystem II (β) are constant in the data set...
October 21, 2016: New Phytologist
Lixia Xiang, Lipan Hu, Weinan Xu, Ai Zhen, Liang Zhang, Xiaohui Hu
Gamma-aminobutyric acid (GABA) is important in plant responses to environmental stresses. We wished to clarify the role of GABA in maintenance of photosynthesis in muskmelon seedlings (Cucumis melo L., cv. Yipintianxia) during saline-alkaline stress. To this end, we assessed the effect of GABA on the structure and function of the photosynthetic apparatus in muskmelon seedlings grown under saline-alkaline stress. These stresses in combination reduced net photosynthetic rate, gas-exchange, and inhibited photosystem II (PSII) electron transport as measured by the JIP-test...
2016: PloS One
Igor Florez-Sarasa, Ko Noguchi, Wagner Araujo, Ana Garcia-Nogales, Alisdair R Fernie, Jaume Flexas, Miquel Ribas-Carbo
The cyclic electron flow around photosystem I (CEF-PSI) increases ATP/NADPH production in the chloroplast acting as an energy balance mechanism. Higher export of reducing power from the chloroplast in CEF-PSI mutants has been correlated with higher mitochondrial alternative oxidase (AOX) capacity and protein amount under high light (HL) conditions. However, in vivo measurements of AOX activity are still required to confirm the exact role of AOX on dissipating the excess of reductant power from the chloroplast...
October 19, 2016: Plant Physiology
Jooyeon Jeong, Kwangryul Baek, Henning Kirst, Anastasios Melis, EonSeon Jin
The Chlamydomonas reinhardtii truncated light-harvesting antenna 4 (tla4) DNA transposon mutant has a pale green phenotype, a lower chlorophyll (Chl) per cell and a higher Chl a/b ratio in comparison with the wild type. It required a higher light intensity for the saturation of photosynthesis and displayed a greater per chlorophyll light-saturated rate of oxygen evolution than the wild type. The Chl antenna size of the photosystems in the tla4 mutant was only about 65% of that measured in the wild type. Molecular genetic analysis revealed that a single plasmid DNA insertion disrupted two genes on chromosome 11 of the mutant...
October 17, 2016: Biochimica et Biophysica Acta
Marta Pintó-Marijuan, Alba Cotado, Eva Fleta-Soriano, Sergi Munné-Bosch
Plants are known for their high capacity to acclimatise to fluctuating environmental conditions. A wide range of environmental conditions can lead to suboptimal physiological efficiency. However, recent studies have shown that plants can withstand repeated periods of stress. To find out how they do it, we studied photosynthetic adjustments to repeated water stress in Aptenia cordifolia: a facultative, invasive CAM species. Plants were subjected to three cycles of water deficit, and photosynthetic parameters and chloroplast antioxidants were quantified to gain an understanding of the mechanisms by which they cope with repeated stress periods...
October 18, 2016: Photosynthesis Research
Nicklaus Fankhauser, Sylvain Aubry
C4 photosynthesis allows highly efficient carbon fixation that originates from tightly regulated anatomical and biochemical modifications of leaf architecture. Recent studies showed that leaf transcriptome modifications during leaf ontogeny of closely related C3 (Tarenaya hassleriana) and C4 (Gynandropsis gynandra) species within the Cleomaceae family existed but they did not identify any dedicated transcriptional networks or factors specifically driving C4 leaf ontogeny. RNAseq analysis provides a steady-state quantification of whole-cell mRNAs but does not allow any discrimination between transcriptional and post-transcriptional processes that may occur simultaneously during leaf ontogeny...
October 18, 2016: Journal of Experimental Botany
K N Sathish Yadav, Dmitry A Semchonok, Lukáš Nosek, Roman Kouřil, Geoffrey Fucile, Egbert J Boekema, Lutz A Eichacker
Photosystem I (PSI) is a pigment-protein complex required for the light-dependent reactions of photosynthesis and participates in light-harvesting and redox-driven chloroplast metabolism. Assembly of PSI into supercomplexes with light harvesting complex (LHC) II, cytochrome b6f (Cytb6f) or NAD(P)H dehydrogenase complex (NDH) has been proposed as a means for regulating photosynthesis. However, structural details about the binding positions in plant PSI are lacking. We analyzed large data sets of electron microscopy single particle projections of supercomplexes obtained from the stroma membrane of Arabidopsis thaliana...
October 15, 2016: Biochimica et Biophysica Acta
Shoubing Wang, Ziran Xu
Increased eutrophication in the recent years has resulted in considerable research focus on identification of methods for preventing cyanobacterial blooms that are rapid and efficient. The objectives of this study were to investigate the effects of dihydroartemisinin and artemether on the growth of Microcystis aeruginosa and to elucidate its mode of action. Variations in cell density, chlorophyll a, soluble protein, malondialdehyde, extracellular alkaline phosphatase activity (APA), and chlorophyll fluorescence parameters (Fv/Fm, ΦPSII, ETR, rapid light curves, fast chlorophyll fluorescence curves on fluorescence intensity, and relative variable fluorescence) were evaluated by lab-cultured experiments...
2016: PloS One
Gang Li, David Talmy, Douglas A Campbell
Light drives phytoplankton productivity, so phytoplankton must exploit variable intensities and durations of light exposure, depending upon season, latitude and depth. We analyzed the growth, photophysiology and composition of small, Thalassiosira pseudonana, and large, Thalassiosira punctigera, centric diatoms from temperate, coastal marine habitats, responding to a matrix of photoperiods and growth light intensities. T. pseudonana showed fastest growth rates under long photoperiods and low to moderate light intensities, while the larger T...
October 18, 2016: Journal of Phycology
Zi-Shan Zhang, Mei-Jun Liu, Renate Scheibe, Jennifer Selinski, Li-Tao Zhang, Cheng Yang, Xiang-Long Meng, Hui-Yuan Gao
The mechanism by which the mitochondrial alternative oxidase (AOX) pathway contributes to PSII photoprotection is in dispute. The current consensus is that the AOX pathway protects photosystems by dissipating excess reducing equivalents that are exported from chloroplasts through the malate/oxaloacetate (Mal/OAA) shuttle, preventing the over-reduction of chloroplasts. Here, using the aox1a Arabidopsis mutant and nine other C3 and C4 species, an additional model of the AOX pathway in PSII photoprotection is proposed...
October 13, 2016: Molecular Plant
Sandrine Bujaldon, Natsumi Kodama, Fabrice Rappaport, Rajagopal Subramanyam, Catherine de Vitry, Yuichiro Takahashi, Francis-André Wollman
The green alga Chlamydomonas reinhardtii contains several light-harvesting chlorophyll a/b complexes (LHC); four major LHCIIs, two minor LHCIIs and nine LHCIs. We characterized three chlorophyll b-less mutants to assess the effect of chlorophyll b deficiency on the function, assembly and stability of these chlorophyll a/b-binding proteins. We identified point mutations in two mutants that inactivate the CAO gene responsible for chlorophyll a to chlorophyll b conversion. All LHCIIs accumulated to wild type levels in a CAO mutant but their light-harvesting function for photosystem-II was impaired...
October 11, 2016: Molecular Plant
Pavel Pospíšil, Yasusi Yamamoto
BACKGROUND: Photosystem II proteins of higher plant chloroplasts are prone to oxidative stress, and most prominently the reaction center-binding D1 protein is damaged under light stress and heat stress. The reactive oxygen species produced under these stress conditions have been suggested to be responsible for the protein injury. SCOPE OF REVIEW: Recently, it has been shown that the primary and secondary products of non-enzymatic and enzymatic lipid peroxidation have a capability to modify photosystem II proteins...
October 11, 2016: Biochimica et Biophysica Acta
Xiao Liu, Shinji Inagaki, Jinlong Gong
Artificial photosynthesis-reduction of CO2 into chemicals and fuels with water oxidation in the presence of sunlight as the energy source-mimics natural photosynthesis in green plants, and is considered to have a significant part to play in future energy supply and protection of our environment. The high quantum efficiency and easy manipulation of heterogeneous molecular photosystems based on metal complexes enables them to act as promising platforms to achieve efficient conversion of solar energy. This Review describes recent developments in the heterogenization of such photocatalysts...
October 14, 2016: Angewandte Chemie
Khoa Nguyen, Michael Vaughn, Paul Frymier, Barry D Bruce
The reduction rate of photo-oxidized Photosystem I (PSI) with various natural and artificial electron donors have been well studied by transient absorption spectroscopy. The electron transfer rate from various donors to P700(+) has been measured for a wide range of photosynthetic organisms encompassing cyanobacteria, algae, and plants. PSI can be a limiting component due to tedious extraction and purification methods required for this membrane protein. In this report, we have determined the in vivo, intracellular cytochrome c 6 (cyt c 6)/PSI ratio in Thermosynechococcus elongatus (T...
October 13, 2016: Photosynthesis Research
Erica Belgio, Stefano Santabarbara, David Bína, Eliška Trsková, Miroslava Herbstová, Radek Kaňa, Giuseppe Zucchelli, Ondřej Prášil
In the present work, we report the first comparative spectroscopic investigation between Photosystems I (PSI) complexes isolated from two red clade algae. Excitation energy transfer was measured in PSI from Chromera velia, an alga possessing a split PsaA protein, and from the model diatom Phaeodactylum tricornutum. In both cases, the estimated effective photochemical trapping time was in the 15-25ps range, i.e. twice as fast as higher plants. In contrast to green phototrophs, the trapping time was rather constant across the whole emission spectrum...
October 11, 2016: Biochimica et Biophysica Acta
Kohtaro Iseki, Yu Takahashi, Chiaki Muto, Ken Naito, Norihiko Tomooka
Breeding salt tolerant plants is difficult without utilizing a diversity of wild crop relatives. Since the genus Vigna (family Fabaceae) is comprised of many wild relatives adapted to various environmental conditions, we evaluated the salt tolerance of 69 accessions of this genus, including that of wild and domesticated accessions originating from Asia, Africa, Oceania, and South America. We grew plants under 50 mM and 200 mM NaCl for two weeks and then measured the biomass, relative quantum yield of photosystem II, leaf Na+ concentrations, and leaf K+ concentrations...
2016: PloS One
David Bína, Zdenko Gardian, Miroslava Herbstová, Radek Litvín
Photosystem I (PSI) is a multi-subunit integral pigment-protein complex that performs light-driven electron transfer from plastocyanin to ferredoxin in the thylakoid membrane of oxygenic photoautotrophs. In order to achieve the optimal photosynthetic performance under ambient irradiance, the absorption cross section of PSI is extended by means of peripheral antenna complexes. In eukaryotes, this role is played mostly by the pigment-protein complexes of the LHC family. The structure of the PSI-antenna supercomplexes has been relatively well understood in organisms harboring the primary plastid: red algae, green algae and plants...
October 12, 2016: Photosynthesis Research
Mariam Awlia, Arianna Nigro, Jiří Fajkus, Sandra M Schmoeckel, Sónia Negrão, Diana Santelia, Martin Trtílek, Mark Tester, Magdalena M Julkowska, Klára Panzarová
Reproducible and efficient high-throughput phenotyping approaches, combined with advances in genome sequencing, are facilitating the discovery of genes affecting plant performance. Salinity tolerance is a desirable trait that can be achieved through breeding, where most have aimed at selecting for plants that perform effective ion exclusion from the shoots. To determine overall plant performance under salt stress, it is helpful to investigate several plant traits collectively in one experimental setup. Hence, we developed a quantitative phenotyping protocol using a high-throughput phenotyping system, with RGB and chlorophyll fluorescence (ChlF) imaging, which captures the growth, morphology, color and photosynthetic performance of Arabidopsis thaliana plants in response to salt stress...
2016: Frontiers in Plant Science
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