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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
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
Zhen Wang, Fuxing Wang, Yechun Hong, Jirong Huang, Huazhong Shi, Jian-Kang Zhu
Chloroplast as the site for photosynthesis is an essential organelle in plants, but little is known about its role in stomatal regulation and drought resistance. In this study, we show that two chloroplastic proteins essential for thylakoid formation negatively regulate drought resistance in Arabidopsis. By screening a mutant pool with T-DNA insertions in nuclear genes encoding chloroplastic proteins, we identified a HCF106 knockdown mutant exhibiting increased resistance to drought stress. The hcf106 mutant displayed elevated levels of reactive oxygen species (ROS) in guard cells, improved stomatal closure and reduced water loss under drought conditions...
October 15, 2016: Plant Physiology
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
Juan Chen, Zhi-Jun Shen, Wei-Zhi Lu, Xiang Liu, Fei-Hua Wu, Gui-Feng Gao, Yi-Ling Liu, Chun-Sheng Wu, Chong-Ling Yan, Hang-Qing Fan, Yi-Hui Zhang, Hai-Lei Zheng
Avicennia marina (Forsk.) Vierh is a widespread mangrove species along the southeast coasts of China. Recently, the outbreak of herbivorous insect, Phyllocnistis citrella Stainton, a leaf miner, have impacted on the growth of A. marina Little is reported about the responses of A. marina to leaf miner infection at the biochemical, physiological and molecular levels. Here, we reported the responses of A. marina to leaf miner infection from the aspects of leaf structure, photosynthesis, and antioxidant system and miner responsive genes expression...
October 13, 2016: Tree Physiology
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
Úrsula Flores-Pérez, Paul Jarvis
Chloroplasts are structurally complex organelles containing ~2000-3000 proteins. They are delimited by a double membrane system or envelope, have an inner aqueous compartment called the stroma, and possess a second internal membrane system called the thylakoids. Thus, determining the suborganellar location of a chloroplast protein is vital to understanding or verifying its function. One way in which protein localization can be addressed is through fractionation. Here we present two rapid and simple methods that may be applied sequentially on the same day: (a) The isolation of intact chloroplasts from Arabidopsis thaliana plants that may be used directly (e...
2017: Methods in Molecular Biology
Judith Hempel, Christopher N Schädle, Jasmin Sprenger, Annerose Heller, Reinhold Carle, Ralf M Schweiggert
Goji berries (Lycium barbarum L.) have been known to contain strikingly high levels of zeaxanthin, while the physical deposition form and bioaccessibility of the latter was yet unknown. In the present study, we associated ripening-induced modifications in the profile of carotenoids with fundamental changes of the deposition state of carotenoids in goji berries. Unripe fruit contained common chloroplast-specific carotenoids being protein-bound within chloroplastidal thylakoids. The subsequent ripening-induced transformation of chloroplasts to tubular chromoplasts was accompanied by an accumulation of up to 36mg/100g FW zeaxanthin dipalmitate and further minor xanthophyll esters, prevailing in a presumably liquid-crystalline state within the nano-scaled chromoplast tubules...
March 1, 2017: Food Chemistry
Beata Mysliwa-Kurdziel, Katalin Solymosi
Thylakoids and chloroplasts harbor several vital metabolic processes, but are most importantly associated with photosynthesis. The undisturbed functioning of this process necessitates the ceaseless synthesis of photosynthetic pigments, including closed tetrapyrroles such as chlorophylls (Chls). Chls probably represent the most abundant natural pigment molecules which are via photosynthesis not only crucial for the autotrophic production of food sources for heterotrophic organisms but have also contributed to oxygen production essential for aerobic metabolism...
October 4, 2016: Mini Reviews in Medicinal Chemistry
Candida J Rebello, Frank L Greenway
The homeostatic controls over eating are inextricably linked to the reward aspects of eating. The result is an integrated response that coordinates the internal milieu with the prevailing environment. Thus, appetite, which reflects a complex interaction among the external environment, behavioral profile, and subjective states as well as the storage and metabolism of energy, has an important role in the regulation of energy balance. In the prevailing food environment which offers an abundance of food choices it is likely that the motivation to consume from a wide range of delectable foods plays a greater role in contributing to overeating than in the past when the motivation to eat was largely governed by metabolic need...
October 7, 2016: Advances in Therapy
Devinder Sandhu, Taylor Atkinson, Andrea Noll, Callie Johnson, Katherine Espinosa, Jessica Boelter, Stephanie Abel, Balpreet K Dhatt, Terese Barta, Eric Singsaas, Sol Sepsenwol, A Susana Goggi, Reid G Palmer
We have identified a viable-yellow and a lethal-yellow chlorophyll-deficient mutant in soybean. Segregation patterns suggested single-gene recessive inheritance for each mutant. The viable- and lethal-yellow plants showed significant reduction of chlorophyll a and b. Photochemical energy conversion efficiency and photochemical reflectance index were reduced in the viable-yellow plants relative to the wildtype, whereas the lethal-yellow plants showed no electron transport activity. The viable-yellow plants displayed reduced thylakoid stacking, while the lethal-yellow plants exhibited failure of proplastid differentiation into normal chloroplasts with grana...
November 2016: Plant Science: An International Journal of Experimental Plant Biology
Masahiro Noshi, Daisuke Mori, Noriaki Tanabe, Takanori Maruta, Shigeru Shigeoka
Reactive oxygen species (ROS) produced in chloroplasts have been proposed to act as signaling molecules for plant immunity through pathogen-associated molecular patterns (PAMPs), such as flg22. To elucidate this process, we herein conducted genetic screening of flg22-sensitive mutants from T-DNA insertion lines lacking chloroplastic H2O2-responsive genes. The results obtained showed that knockout mutants lacking a clade IV TGA transcription factor, TGA10, were more sensitive to the flg22 treatment than wild-type plants...
November 2016: Plant Science: An International Journal of Experimental Plant Biology
A N Diakonova, S S Khrushchev, I B Kovalenko, G Yu Riznichenko, A B Rubin
Ferredoxin (Fd) protein transfers electrons from photosystem I (PSI) to ferredoxin:NADP(+)-reductase (FNR) in the photosynthetic electron transport chain, as well as other metabolic pathways. In some photosynthetic organisms including cyanobacteria and green unicellular algae under anaerobic conditions Fd transfers electrons not only to FNR but also to hydrogenase-an enzyme which catalyzes reduction of atomic hydrogen to H2. One of the questions posed by this competitive relationship between proteins is which characteristics of thylakoid stroma media allow switching of the electron flow between the linear path PSI-Fd-FNR-NADP(+) and the path PSI-Fd-hydrogenase-H2...
October 7, 2016: Physical Biology
David J Lea-Smith, Maite L Ortiz-Suarez, Tchern Lenn, Dennis J Nurnberg, Laura L Baers, Matthew P Davey, Lucia Parolini, Roland G Huber, Charles A R Cotton, Giulia Mastroianni, Paolo Bombelli, Petra Ungerer, Tim J Stevens, Alison G Smith, Peter J Bond, Conrad W Mullineaux, Christopher J Howe
Cyanobacteria are intricately organized, incorporating an array of internal thylakoid membranes, the site of photosynthesis, into cells no larger than other bacteria. They also synthesize C15-C19 alkanes and alkenes, which results in substantial production of hydrocarbons in the environment. All sequenced cyanobacteria encode hydrocarbon biosynthesis pathways, suggesting an important, undefined physiological role for these compounds. Here we demonstrate that hydrocarbon deficient mutants of Synechococcus sp...
October 5, 2016: Plant Physiology
Fei Wang, Yafei Qi, Alizée Malnoë, Yves Choquet, Francis-André Wollman, Catherine de Vitry
In Chlamydomonas reinhardtii, the major protease involved in the maintenance of the photosynthetic machinery in thylakoid membranes - the FtsH protease - forms mostly large hetero-oligomers (∼1 MDa) comprising FtsH1 and FtsH2 subunits, whatever the light intensity for growth. Upon high light exposure, the FtsH subunits display a shorter half-life, which is counterbalanced by an increase in FTSH1/2 mRNA levels, resulting in a modest upregulation of FtsH1/2 proteins. Furthermore, we show that high light increases the protease activity through a hitherto unnoticed redox-controlled reduction of intermolecular disulfide bridges...
October 1, 2016: Molecular Plant
Jarosław Króliczewski, Małgorzata Piskozub, Rafał Bartoszewski, Bożena Króliczewska
The cytochrome b6 f complex occupies an electrochemically central position in the electron-transport chain bridging the photosynthetic reaction center of PS I and PS II. In plants, the subunits of these thylakoid membrane protein complexes are both chloroplast and nuclear encoded. How the chloroplast-encoded subunits of multi-spanning cytochrome b6 are targeted and inserted into the thylakoid membrane is not fully understood. Experimental approaches to evaluate the cytochrome b6 import mechanism in vivo have been limited to bacterial membranes and were not a part of the chloroplast environment...
October 4, 2016: Scientific Reports
Geoffry A Davis, Atsuko Kanazawa, Mark Aurel Schöttler, Kaori Kohzuma, John E Froehlich, A William Rutherford, Mio Satoh-Cruz, Deepika Minhas, Stefanie Tietz, Amit Dhingra, David M Kramer
The thylakoid proton motive force (pmf) generated during photosynthesis is the essential driving force for ATP production; it is also a central regulator of light capture and electron transfer. We investigated the effects of elevated pmf on photosynthesis in a library of Arabidopsis thaliana mutants with altered rates of thylakoid lumen proton efflux, leading to a range of steady-state pmf extents. We observed the expected pmf-dependent alterations in photosynthetic regulation, but also strong effects on the rate of photosystem II (PSII) photodamage...
October 4, 2016: ELife
Jennifer Heidrich, Adrien Thurotte, Dirk Schneider
The photosynthetic light reaction takes place within the thylakoid membrane system in cyanobacteria and chloroplasts. Besides its global importance, the biogenesis, maintenance and dynamics of this membrane system are still a mystery. In the last two decades, strong evidence supported the idea that these processes involve IM30, the inner membrane-associated protein of 30kDa, a protein also known as the vesicle-inducing protein in plastids 1 (Vipp1). Even though we just only begin to understand the precise physiological function of this protein, it is clear that interaction of IM30 with membranes is crucial for biogenesis of thylakoid membranes...
September 30, 2016: Biochimica et Biophysica Acta
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