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Bahtijor Rasulov, Eero Talts, Ulo Niinemets
Plant isoprene emissions respond to light and temperature similarly to photosynthesis, but CO2-dependencies of isoprene emission and photosynthesis are profoundly different with photosynthesis increasing and isoprene emissions decreasing with increasing CO2 concentration due to reasons not yet understood. We studied isoprene emission, net assimilation rate and chlorophyll fluorescence under different CO2 and O2 concentrations in the strong isoprene emitter hybrid aspen (Populus tremula x P. tremuloides), and used rapid changes in ambient CO2 or O2 concentrations or light level to induce oscillations...
October 21, 2016: Plant Physiology
Florian A Busch, Rowan F Sage
The biochemical model of C3 photosynthesis by Farquhar, von Caemmerer and Berry (FvCB) assumes that photosynthetic CO2 assimilation is limited by one of three biochemical processes that are not always easily discerned. This leads to improper assessments of biochemical limitations that limit the accuracy of the model predictions. We use the sensitivity of rates of CO2 assimilation and photosynthetic electron transport to changes in O2 and CO2 concentration in the chloroplast to evaluate photosynthetic limitations...
October 21, 2016: New Phytologist
E Levy, M Byrne, D J Coates, B M Macdonald, S McArthur, S van Leeuwen
The influence of geographic range on species persistence has long been of interest and there is a need for a better understanding of the genetic consequences for species with restricted distributions, particularly with the increasing rate of global species extinctions. However, the genetic effects of restricted range are often confounded by the impacts of population distribution. We compared chloroplast and nuclear genetic diversity and differentiation in two acacias, the restricted, patchily distributed Acacia atkinsiana and the widespread, semi-continuously distributed A...
2016: PloS One
Takashi Nakada, Masaru Tomita
New strains of wall-less unicellular volvocalean flagellate were isolated from a freshwater environment in Japan. Observations of the alga, described here as Hapalochloris nozakii Nakada, gen. et sp. nov., were made under light, fluorescence, and electron microscopes. Each vegetative cell had two flagella, four contractile vacuoles, and a spirally furrowed cup-shaped chloroplast with an axial pyrenoid, and mitochondria located in the furrows. Based on the morphology, H. nozakii was distinguished from other known wall-less volvocalean flagellates...
October 21, 2016: Journal of Phycology
Shibiao Wan, Man-Wai Mak, Sun-Yuan Kung
In the post-genomic era, the number of unreviewed protein sequences is remarkably larger and grows tremendously faster than that of reviewed ones. However, existing methods for protein subchloroplast localization often ignore the information from these unlabelled proteins. This paper proposes a multi-label predictor based on ensemble linear neighborhood propagation (LNP), namely LNP-Chlo, which leverages hybrid sequence-based feature information from both labelled and unlabelled proteins for predicting localization of both single- and multi-label chloroplast proteins...
October 21, 2016: Journal of Proteome Research
Saura R Silva, Yani C A Diaz, Helen Alves Penha, Daniel G Pinheiro, Camila C Fernandes, Vitor F O Miranda, Todd P Michael, Alessandro M Varani
Lentibulariaceae is the richest family of carnivorous plants spanning three genera including Pinguicula, Genlisea, and Utricularia. Utricularia is globally distributed, and, unlike Pinguicula and Genlisea, has both aquatic and terrestrial forms. In this study we present the analysis of the chloroplast (cp) genome of the terrestrial Utricularia reniformis. U. reniformis has a standard cp genome of 139,725bp, encoding a gene repertoire similar to essentially all photosynthetic organisms. However, an exclusive combination of losses and pseudogenization of the plastid NAD(P)H-dehydrogenase (ndh) gene complex were observed...
2016: PloS One
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
Tofayel Ahmed, Zhan Yin, Shashi Bhushan
Protein synthesis in the chloroplast is mediated by the chloroplast ribosome (chloro-ribosome). Overall architecture of the chloro-ribosome is considerably similar to the Escherichia coli (E. coli) ribosome but certain differences are evident. The chloro-ribosome proteins are generally larger because of the presence of chloroplast-specific extensions in their N- and C-termini. The chloro-ribosome harbours six plastid-specific ribosomal proteins (PSRPs); four in the small subunit and two in the large subunit...
October 20, 2016: Scientific Reports
Mina Momayyezi, Robert D Guy
In Populus trichocarpa (black cottonwood), net photosynthesis (An ) varies with latitude and, in northern genotypes, is supported by higher stomatal conductance (gs ). We report here a parallel cline in mesophyll conductance (gm ) and link this variation to carbonic anhydrase (CA) activity. Using concurrent carbon isotope discrimination and chlorophyll fluorescence methods, we examined the effects of acetazolamide, an inhibitor of CA, on gm in six representative genotypes (three from either end of the north-south cline)...
October 20, 2016: Plant, Cell & Environment
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
Dekai Wang, Heqin Liu, Guowei Zhai, Liangsheng Wang, Jianfeng Shao, Yuezhi Tao
Functional chloroplast generation depends on the precise coordination of gene expression between the plastid and the nucleus and is essential for plant growth and development. In this study, a rice (Oryza sativa) mutant that exhibited albino and seedling-lethal phenotypes was isolated from a(60)Co-irradiated rice population. The mutant gene was identified as an ortholog of the Arabidopsis plastid transcriptionally active chromosome protein 2 (pTAC2) gene, and the mutant strain was designated osptac2. Sequence and transcription analyses showed that OspTAC2 encodes a putative chloroplast protein consisting of 10 pentratricopeptide repeat (PPR) domains and a C-terminal small MutS-related (SMR) domain...
September 15, 2016: Journal of Genetics and Genomics, Yi Chuan Xue Bao
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
Wei Tong, Tae-Sung Kim, Yong-Jin Park
BACKGROUND: Chloroplast genome variations have been detected, despite its overall conserved structure, which has been valuable for plant population genetics and evolutionary studies. Here, we described chloroplast variation architecture of 383 rice accessions from diverse regions and different ecotypes, in order to mine the rice chloroplast genome variation architecture and phylogenetic. RESULTS: A total of 3677 variations across the chloroplast genome were identified with an average density of 27...
December 2016: Rice
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
Min Chen, Meiling Ji, Binbin Wen, Li Liu, Shaoxuan Li, Xiude Chen, Dongsheng Gao, Ling Li
Golden2-like (GLK) transcription factors are members of the GARP family of Myb transcription factors with an established relationship to chloroplast development in the plant kingdom. In the last century, Golden2 was proposed as a second golden producing factor and identified as controlling cellular differentiation in maize leaves. Then, GLKs were also found to play roles in disease defense and their function is conserved in regulating chloroplast development. Recently, research on GLKs has rapidly increased and shown that GLKs control chloroplast development in green and non-green tissues...
2016: Frontiers in Plant Science
Jinping Zhao, Xian Zhang, Yiguo Hong, Yule Liu
In plants, the chloroplast is the organelle that conducts photosynthesis. It has been known that chloroplast is involved in virus infection of plants for approximate 70 years. Recently, the subject of chloroplast-virus interplay is getting more and more attention. In this article we discuss the different aspects of chloroplast-virus interaction into three sections: the effect of virus infection on the structure and function of chloroplast, the role of chloroplast in virus infection cycle, and the function of chloroplast in host defense against viruses...
2016: Frontiers in Microbiology
Masaki Odahara, Yusuke Kobayashi, Toshiharu Shikanai, Yoshiki Nishimura
The chloroplast (cp) genome is organized as nucleoids that are dispersed throughout the cp stroma. Previously, a cp homolog of bacterial recombinase RecA (cpRECA) was shown to be involved in maintenance of cp genome integrity by repairing damaged cpDNA and by suppressing aberrant recombination between short dispersed repeats (SDRs) in the moss Physcomitrella patens. Here, overexpression and knockdown analysis of cpRECA in the green alga Chlamydomonas reinhardtii revealed that cpRECA was involved in cp nucleoid dynamics as well as having a role in maintaining cp genome integrity...
October 17, 2016: Plant Physiology
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
Steven J Burgess, Ignasi Granero-Moya, Mathieu J Grangé-Guermente, Chris Boursnell, Matthew J Terry, Julian M Hibberd
C4 photosynthesis acts as a carbon concentrating mechanism that leads to large increases in photosynthetic efficiency. The C4 pathway is found in more than 60 plant lineages(1) but the molecular enablers of this evolution are poorly understood. In particular, it is unclear how non-photosynthetic proteins in the ancestral C3 system have repeatedly become strongly expressed and integrated into photosynthesis gene regulatory networks in C4 leaves. Here, we provide clear evidence that in C3 leaves, genes encoding key enzymes of the C4 pathway are already co-regulated with photosynthesis genes and are controlled by both light and chloroplast-to-nucleus signalling...
October 17, 2016: Nature Plants
Bernardo Duarte, Maria Teresa Cabrita, Carla Gameiro, Ana Rita Matos, Rita Godinho, João Carlos Marques, Isabel Caçador
A profound analysis of A. tripolium photochemical traits under salinity exposure is lacking in the literature, with very few references focusing on its fatty acid profile role in photophysiology. To address this, the deep photochemical processes were evaluated by Pulse Amplitude Modulated (PAM) Fluorometry coupled with a discrimination of its leaf fatty acid profile. Plants exposed to 125-250 mM NaCl showed higher photochemical light harvesting efficiencies and lower energy dissipation rates. under higher NaCl exposure, there is evident damage of the oxygen evolving complexes (OECs)...
October 17, 2016: Plant Biology
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