Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Plants (Basel) ; 10(10)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34685884

RESUMO

Global warming and the associated climate change are imposing abiotic stress on plants. Abiotic factors are crucial for plant productivity, survival, and reproduction. Eight sunflower hybrids were tested in conditions of different water availability and with combinations of different temperatures and irradiation. The changes in the photosynthetic efficiency were measured in the morning (control conditions: 2013, 25.8 °C and 349.1 W m-2; 2014, 21.8 °C and 296.4 W m-2) and afternoon (the combination of increased temperatures and high irradiation: 2013, 34 °C and 837.9 W m-2; 2014, 29.4 °C and 888.9 W m-2) at a flowering stage in rainfed or irrigated conditions. The measurement time (morning and afternoon conditions) had a statistically significant effect on all the tested parameters. The performance index (PIABS) in 2013 and the maximum quantum yield of photosystem II (TR0/ABS) in 2014 are the only parameters significantly affected by the irrigation. As a result of the combined effect of increased temperatures and high irradiation, PIABS values decreased by 73-92% in rainfed conditions and by 63-87% in irrigated conditions in 2013, depending on the hybrid, while in 2014, the decrease varied between 70 and 86%. The TR0/ABS decrease was 7-17% in 2013, depending on the hybrid, and 6-12% in 2014, both in rainfed and irrigated conditions. The principal component analysis confirmed the effect of the combination of increased temperatures and high irradiation on hybrids, sorting them exclusively according to the time of measurement. All investigated parameters highly fluctuated between hybrids but without observable trends for the morning and afternoon conditions, as well as for irrigation. Plants' reaction to the combination of increased temperatures and high irradiation manifested as a change in their photosynthetic efficiency, i.e., the photosynthetic apparatus' functioning was impaired.

2.
J Plant Physiol ; 243: 153048, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31639536

RESUMO

Investigations of the luminal immunophilin AtCYP38 (cyclophilin 38) in Arabidopsis thaliana (At), the orthologue of the complex immunophilin TLP40 from Spinacia oleracea, revealed its involvement in photosystem II (PSII) repair and assembly, biogenesis of PSII complex, and cellular signalling. However, the main physiological roles of AtCYP38 and TLP40 are related to regulation of thylakoid PP2A-type phosphatase involved in PSII core protein dephosphorylation, and chaperone function during protein folding. Here we further investigate physiological roles of AtCYP38 and analyse the ultrastructure of chloroplasts from cyp38-2 plants. Transmission electron microscopy followed by quantitative micrography revealed modifications in thylakoid stacking. We also confirm that the depletion of AtCYP38 influences PSII performance, which leads to stunted phenotype of cyp38-2 plants.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Ciclofilinas/genética , Complexo de Proteína do Fotossistema II/metabolismo , Tilacoides/metabolismo , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Cloroplastos/ultraestrutura , Ciclofilinas/metabolismo , Microscopia Eletrônica de Transmissão
3.
Front Plant Sci ; 10: 450, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31031786

RESUMO

Soil salinity is severely affecting crop productivity in many countries, particularly in the Mediterranean area. To evaluate early plant responses to increased salinity and characterize tolerance markers, three important Brassica crops - Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata) and kale (B. oleracea var. acephala) were subjected to short-term (24 h) salt stress by exposing them to NaCl at concentrations of 50, 100, or 200 mM. Physiological (root growth, photosynthetic performance parameters, and Na+/K+ ratio) and biochemical parameters (proline content and lipid peroxidation as indicated by malondialdehyde, MDA, levels) in the plants' roots and leaves were then measured. Photosynthetic parameters such as the total performance index PItotal (describing the overall efficiency of PSI, PSII and the intersystem electron transport chain) appeared to be the most salinity-sensitive parameter and informative stress marker. This parameter was decreased more strongly in Chinese cabbage than in white cabbage and kale. It indicated that salinity reduced the capacity of the photosynthetic system for efficient energy conversion, particularly in Chinese cabbage. In parallel with the photosynthetic impairments, the Na+/K+ ratio was highest in Chinese cabbage leaves and lowest in kale leaves while kale root is able to keep high Na+/K+ ratio without a significant increase in MDA. Thus Na+/K+ ratio, high in root and low in leaves accompanying with low MDA level is an informative marker of salinity tolerance. The crops' tolerance was positively correlated with levels of the stress hormone abscisic acid (ABA) and negatively correlated with levels of jasmonic acid (JA), and jasmonoyl-L-isoleucine (JA-Ile). Furthermore, salinity induced contrasting changes in levels of the growth-promoting hormones brassinosteroids (BRs). The crop's tolerance was positively correlated with levels of BR precursor typhasterol while negatively with the active BR brassinolide. Principal Component Analysis revealed correlations in observed changes in phytohormones, biochemical, and physiological parameters. Overall, the results show that kale is the most tolerant of the three species and Chinese cabbage the most sensitive to salt stress, and provide holistic indications of the spectrum of tolerance mechanisms involved.

4.
Plant Physiol Biochem ; 133: 142-148, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30419464

RESUMO

Since lignin greatly affects stem strength, which is an important agronomical trait, understanding the relationship between lodging resistance and lignin synthesis is important in barley breeding and selection processes. The aim of the study was to reveal the connection between physiological aspects of lignin synthesis and genetic background of barley cultivars with different lodging phenotype. Three barley cultivars Astor, Scarlett and Jaran were compared by measuring lignin, cellulose and total soluble phenolics content, phenylalanine ammonia-lyase activity (PAL) and expression of cinnamoyl-CoA reductase (CCR) and cinnamyl-alcohol dehydrogenase (CAD) in three lower internodes at flowering and grain filling stage. To assess their genetic background simple sequence repeats (SSR) markers, connected to lodging resistance and plant height, were analyzed. Compared to lodging susceptible cultivars Scarlett and Jaran, a lodging resistant cultivar Astor revealed different dynamics of lignin synthesis and deposition, showing higher PAL activity and total soluble phenolics content as well as higher expression of CCR and CAD genes in the second internode at grain filling stage. Analysis of SSR markers associated with quantitative trait loci (QTL) for lodging resistance revealed that Astor discriminates from Scarlett and Jaran by marker Bmag337 connected with elongation of the second internode. Lignification process is under a strong influence of genotype and environmental factors which determine lignin synthesis dynamics and deposition of lignin in the cell walls of barley.


Assuntos
Hordeum/metabolismo , Lignina/biossíntese , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas , Hordeum/genética , Lignina/genética , Proteínas de Plantas/genética , Especificidade da Espécie
5.
Antioxidants (Basel) ; 7(10)2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30241411

RESUMO

Although Aloe vera contains numerous bioactive components, the activity principles of widely used A. vera extracts are uncertain. Therefore, we analyzed the effects of genuine A. vera aqueous extract (AV) on human cells with respect to the effects of hydrogen peroxide (H2O2) and 4-hydroxynonenal (HNE). Fully developed A. vera leaves were harvested and analyzed for vitamin C, carotenoids, total soluble phenolic content, and antioxidant capacity. Furthermore, human cervical cancer (HeLa), human microvascular endothelial cells (HMEC), human keratinocytes (HaCat), and human osteosarcoma (HOS) cell cultures were treated with AV extract for one hour after treatment with H2O2 or HNE. The cell number and viability were determined using Trypan Blue, and endogenous reactive oxygen species (ROS) production was determined by fluorescence, while intracellular HNE⁻protein adducts were measured for the first time ever by genuine cell-based HNE⁻His ELISA. The AV extract expressed strong antioxidant capacities (1.1 mmol of Trolox eq/g fresh weight) and cell-type-specific influence on the cytotoxicity of H2O2, as well as on endogenous production of ROS and HNE⁻protein adducts induced by HNE treatment, while AV itself did not induce production of ROS or HNE⁻protein adducts at all. This study, for the first time, revealed the importance of HNE for the activity principles of AV. Since HMEC cells were the most sensitive to AV, the effects of AV on microvascular endothelia could be of particular importance for the activity principles of Aloe vera extracts.

6.
Int J Mol Sci ; 19(10)2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30241414

RESUMO

Drought is one of the major abiotic stresses affecting the productivity of Brassica crops. To understand the role of phytohormones in drought tolerance, we subjected Chinese cabbage (B. rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata), and kale (B. oleracea var. acephala) to drought and examined the stress response on the physiological, biochemical and hormonal levels. The phytohormones abscisic acid (ABA), auxin indole-3-acetic acid (IAA), brassinosteroids (BRs), cytokinins (CKs), jasmonates (JAs), and salicylic acid (SA) were analyzed by ultra-high-performance liquid chromatography⁻tandem mass spectrometry (UHPLC-MS/MS). Based on the physiological and biochemical markers the Chinese cabbage exhibited the lowest tolerance, followed by the white cabbage, while the kale appeared to be the most tolerant to drought. The drought tolerance of the kale correlated with increased levels of SA, ABA, IAA, CKs iP(R) and cZ(R), and typhasterol (TY), a precursor of active BRs. In contrast, the drought sensitivity of the Chinese cabbage correlated with a significant increase in ABA, JAs and the active BRs castasterol (CS) and brassinolide (BL). The moderately tolerant white cabbage, positioned between the kale and Chinese cabbage, showed more similarity in terms of the phytohormone patterns with the kale. We concluded that the drought tolerance in Brassicaceae is mostly determined by the increased endogenous levels of IAA, CKs, ABA and SA and the decreased levels of active BRs.


Assuntos
Brassica/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Estresse Fisiológico , Brassica/classificação , Brassica/genética , Perfilação da Expressão Gênica , Proteínas de Plantas/metabolismo
7.
Plant Physiol Biochem ; 125: 74-84, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29427890

RESUMO

Salinity is one of major abiotic stresses affecting Brassica crop production. Here we present investigations into the physiological, biochemical, and hormonal components of the short-term salinity stress response in Chinese cabbage seedlings, with particular emphasis on the biosynthesis and metabolism of auxin indole-3-acetic acid (IAA). Upon salinity treatments (50-200 mM NaCl) IAA level was elevated in a dose dependent manner reaching 1.6-fold increase at the most severe salt treatment in comparison to the control. IAA precursor profiling suggested that salinity activated the indole-3-acetamide and indole-3-acetaldoxime biosynthetic pathways while suppressing the indole-3-pyruvic acid pathway. Levels of the IAA catabolites 2-oxoindole-3-acetic acid and indole-3-acetic acid-aspartate increased 1.7- and 2.0-fold, respectively, under the most severe treatment, in parallel with those of IAA. Conversely, levels of the ester conjugate indole-3-acetyl-1-O-ß-d-glucose and its catabolite 2-oxoindole-3-acetyl-1-O-ß-d-glucose decreased 2.5- and 7.0-fold, respectively. The concentrations of stress hormones including jasmonic acid and jasmonoyl-isoleucine (JA and JA-Ile), salicylic acid (SA) and abscisic acid (ABA) confirmed the stress induced by salt treatment: levels of JA and JA-Ile increased strongly under the mildest treatment, ABA only increased under the most severe treatment, and SA levels decreased dose-dependently. These hormonal changes were related to the observed changes in biochemical stress markers upon salt treatments: reductions in seedling fresh weight and root growth, decreased photosynthesis rate, increased levels of reactive oxygen species, and elevated proline content and the Na+/K+ ratio. Correlations among auxin profile and biochemical stress markers were discussed based on Pearson's coefficients and principal component analysis (PCA).


Assuntos
Brassica rapa/metabolismo , Ácidos Indolacéticos/metabolismo , Plântula/metabolismo , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos
8.
J Plant Physiol ; 209: 1-10, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27987432

RESUMO

Molecular processes involved in photosystem II adaptation of woody species to diurnal changes in light and temperature conditions are still not well understood. Regarding this, here we investigated differences between young and mature leaves of common fig (Ficus carica L.) in photosynthetic performance as well as accumulation of the main photosynthetic proteins: light harvesting complex II, D1 protein and Rubisco large subunit. Investigated leaf types revealed different adjustment mechanisms to keep effective photosynthesis. Rather stable diurnal accumulation of light harvesting complex II in mature leaves enabled efficient excitation energy utilization (negative L-band) what triggered faster D1 protein degradation at high light. However, after photoinhibition, greater accumulation of D1 during the night enabled them faster recovery. So, the most photosynthetic parameters, as the maximum quantum yield for primary photochemistry, electron transport and overall photosynthetic efficiency in mature leaves successfully restored to their initial values at 1a.m. Reduced connectivity of light harvesting complexes II to its reaction centers (positive L-band) in young leaves increased dissipation of excess light causing less pressure to D1 and its slower degradation. Decreased electron transport in young leaves, due to reduced transfer beyond primary acceptor QA- most probably additionally induced degradation of Rubisco large subunit what consequently led to the stronger decrease of overall photosynthetic efficiency in young leaves at noon.


Assuntos
Ritmo Circadiano , Ficus/fisiologia , Fotossíntese , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Clorofila/metabolismo , Clorofila A , Fluorescência , Cinética , Fótons
9.
Aquat Toxicol ; 175: 117-26, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27015565

RESUMO

The effect of two concentrations of cobalt (Co(2+)) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72h after the start of the exposure. Higher concentration of cobalt (1mM) induced growth inhibition while lower concentration (0.01mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co(2+) especially at the higher concentration where decreased electron transport beyond primary quinone acceptor QA(-) and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co(2+) concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals.


Assuntos
Araceae/efeitos dos fármacos , Cobalto/toxicidade , Transporte de Elétrons/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Antioxidantes/metabolismo , Membrana Celular/efeitos dos fármacos , Clorofila/metabolismo , Clorofila A , Ativação Enzimática/efeitos dos fármacos , Fluorescência , Crescimento/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Oxirredução/efeitos dos fármacos , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/toxicidade
10.
Arh Hig Rada Toksikol ; 66(2): 141-52, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26110476

RESUMO

Metals have a variety of negative outcomes on plants, essential components of any ecosystem. The effects of CdCl2 (5 µmol L-1), ZnCl2 (25 or 50 µmol L-1), and CuCl2 (2.5 or 5 µmol L-1) and combinations of CdCl2 with either ZnCl2 or CuCl2 on the growth, photosynthetic pigments, and photosystem II (PSII) efficiency of duckweed (Lemna minor L.) were investigated. All of the treatments caused growth inhibition and remarkable metal accumulation in plant tissue after 4 and 7 days. In the combined treatments, the accumulation of each metal applied was lesser in comparison to treatments with single metals. After 4 days, all of the treatments generally diminished chlorophyll a content and decreased the maximum quantum yield (Fv/Fm) and effective quantum yield (ΔF/F'm) of PSII. However, after 7 days of exposure to a combination of Cd and Zn, pigment content and PSII activity recovered to control levels. A higher concentration of Cu (5 µmol L-1) as well as Cd in combination with Cu had a prolonged inhibitory effect on photosynthetic features. Our results suggest that growth inhibition was due to the toxic effect of absolute metal quantity in plant tissue. Zn counteracted Cd uptake, as seen from the recovery of pigment content and PSII efficiency in plants exposed for 7 days to the Cd and Zn combination. Cu-induced oxidative stress led to a prolonged inhibitory effect in plants treated both with a higher concentration of Cu (5 µmol L-1) and simultaneously with Cd and Cu. Our findings could contribute to general knowledge on anthropogenic and environmental contaminants that endanger plant communities and significantly disrupt the sensitive balance of an ecosystem by influencing photosynthetic mechanisms.


Assuntos
Araceae/efeitos dos fármacos , Araceae/crescimento & desenvolvimento , Cádmio/toxicidade , Cobre/toxicidade , Fotossíntese/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Zinco/toxicidade , Croácia , Inibidores do Crescimento/toxicidade
11.
Sci Rep ; 5: 10085, 2015 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-26041075

RESUMO

In photosynthesis, final electron transfer from ferredoxin to NADP(+) is accomplished by the flavo enzyme ferredoxin:NADP(+) oxidoreductase (FNR). FNR is recruited to thylakoid membranes via integral membrane thylakoid rhodanase-like protein TROL. We address the fate of electrons downstream of photosystem I when TROL is absent. We have employed electron paramagnetic resonance (EPR) spectroscopy to study free radical formation and electron partitioning in TROL-depleted chloroplasts. DMPO was used to detect superoxide anion (O2(.-)) formation, while the generation of other free radicals was monitored by Tiron. Chloroplasts from trol plants pre-acclimated to different light conditions consistently exhibited diminished O2(.-) accumulation. Generation of other radical forms was elevated in trol chloroplasts in all tested conditions, except for the plants pre-acclimated to high-light. Remarkably, dark- and growth light-acclimated trol chloroplasts were resilient to O2(.-) generation induced by methyl-viologen. We propose that the dynamic binding and release of FNR from TROL can control the flow of photosynthetic electrons prior to activation of the pseudo-cyclic electron transfer pathway.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Transporte de Elétrons , Ferredoxina-NADP Redutase/metabolismo , Proteínas de Membrana/metabolismo , Redes e Vias Metabólicas , Fotossíntese , Cloroplastos/metabolismo , Oxigênio/metabolismo , Fotoperíodo , Espécies Reativas de Oxigênio/metabolismo
12.
J Integr Plant Biol ; 56(7): 695-708, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24521148

RESUMO

Chlorophyll fluorescence transient from initial to maximum fluorescence ("P" step) throughout two intermediate steps ("J" and "I") (JIP-test) is considered a reliable early quantitative indicator of stress in plants. The JIP-test is particularly useful for crop plants when applied in variable field environments. The aim of the present study was to conduct a quantitative trait loci (QTL) analysis for nine JIP-test parameters in maize during flowering in four field environments differing in weather conditions. QTL analysis and identification of putative candidate genes might help to explain the genetic relationship between photosynthesis and different field scenarios in maize plants. The JIP-test parameters were analyzed in the intermated B73 × Mo17 (IBM) maize population of 205 recombinant inbred lines. A set of 2,178 molecular markers across the whole maize genome was used for QTL analysis revealing 10 significant QTLs for seven JIP-test parameters, of which five were co-localized when combined over the four environments indicating polygenic inheritance and pleiotropy. Our results demonstrate that QTL analysis of chlorophyll fluorescence parameters was capable of detecting one pleiotropic locus on chromosome 7, coinciding with the gene gst23 that may be associated with efficient photosynthesis under different field scenarios.


Assuntos
Zea mays/genética , Zea mays/metabolismo , Clorofila/genética , Clorofila/metabolismo , Clorofila A , Locos de Características Quantitativas/genética
13.
Tree Physiol ; 32(3): 346-54, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22427374

RESUMO

The fate of chloroplast DNA (cpDNA) during plastid development and conversion between various plastid types is still not very well understood. This is especially true for the cpDNA found in plastids of naturally senescing leaves. Here, we describe changes in plastid nucleoid structure accompanied with cpDNA degradation occurring during natural senescence of the free-growing deciduous woody species Acer pseudoplatanus L. Natural senescence was investigated using three types of senescing leaves: green (G), yellow-green (YG) and yellow (Y). The extent of senescence was evaluated at the level of photosynthetic pigment degradation, accumulation of starch and plastid ultrastructure. Determination of cpDNA amount was carried out by in planta visualization with 4,6-diamidino-2-phenylindole, by Southern hybridization, and by dot-blot using an rbcL gene probe. During natural senescence, plastid nucleoids undergo structural rearrangements accompanied by an almost complete loss of cpDNA. Furthermore, senescence-associated protein components exhibiting strong binding to an ∼10kbp rbcL-containg cpDNA fragment were identified. This interaction might be important for rbcL expression and Rubisco degradation during the course of natural senescence in trees.


Assuntos
Acer/química , Acer/fisiologia , Senescência Celular/fisiologia , DNA de Cloroplastos/química , Ribulose-Bifosfato Carboxilase/genética , Acer/enzimologia , Acer/genética , Carotenoides/análise , Clorofila/análise , Clorofila A , Cloroplastos/genética , Clima , DNA de Cloroplastos/genética , Folhas de Planta/química , Folhas de Planta/genética , Folhas de Planta/fisiologia , Amido/metabolismo
14.
Plant Physiol Biochem ; 49(4): 368-76, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21334907

RESUMO

Different structural and functional changes take place during leaf development. Since some of them are highly connected to oxidative metabolism, regulation of reactive oxygen species (ROS) abundance is required. Most of the reactive oxygen species ROS in plant cells are produced in chloroplasts as a result of highly energetic reactions of photosynthesis. The aim of our study was to examine the changes in concentration of oxidative stress parameters (TBARS - thiobarbituric acid-reacting substances and protein carbonyls) as well as antioxidative strategies during development of maple (Acer platanoides L.) leaves in the light of their enhanced photosynthetic performance. We reveal that biogenesis of the photosynthetic apparatus during maple leaf maturation corresponded with oxidative damage of lipids, but not proteins. In addition, antioxidative responses in young leaves differed from that in older leaves. Young leaves had high values of non-photochemical quenching (NPQ) and catalase (CAT, EC 1.11.1.6) activity which declined during the maturation process. Developing leaves were characterized by an increase in TBARS level, the content of non-enzymatic antioxidants as well as ascorbate peroxidase activity (APX, EC 1.11.1.11), while the content of protein carbonyls decreased with leaf maturation. Fully developed leaves had the highest lipid peroxidation level accompanied by a maximum in ascorbic acid content and superoxide dismutase activity (SOD, EC1.15.1.1). These observations imply completely different antioxidative strategies during leaf maturation enabling them to perform their basic function.


Assuntos
Acer/metabolismo , Antioxidantes/metabolismo , Peroxidação de Lipídeos , Estresse Oxidativo , Fotossíntese , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Ascorbato Peroxidases/metabolismo , Ácido Ascórbico/metabolismo , Catalase/metabolismo , Complexos de Proteínas Captadores de Luz/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Carbonilação Proteica , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
15.
Plant J ; 60(5): 783-94, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19682289

RESUMO

Working in tandem, two photosystems in the chloroplast thylakoid membranes produce a linear electron flow from H(2)O to NADP(+). Final electron transfer from ferredoxin to NADP(+) is accomplished by a flavoenzyme ferredoxin:NADP(+) oxidoreductase (FNR). Here we describe TROL (thylakoid rhodanese-like protein), a nuclear-encoded component of thylakoid membranes that is required for tethering of FNR and sustaining efficient linear electron flow (LEF) in vascular plants. TROL consists of two distinct modules; a centrally positioned rhodanese-like domain and a C-terminal hydrophobic FNR binding region. Analysis of Arabidopsis mutant lines indicates that, in the absence of TROL, relative electron transport rates at high-light intensities are severely lowered accompanied with significant increase in non-photochemical quenching (NPQ). Thus, TROL might represent a missing thylakoid membrane docking site for a complex between FNR, ferredoxin and NADP(+). Such association might be necessary for maintaining photosynthetic redox poise and enhancement of the NPQ.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Ferredoxina-NADP Redutase/metabolismo , Proteínas de Membrana/metabolismo , Tilacoides/metabolismo , Sequência de Aminoácidos , Arabidopsis/genética , Arabidopsis/ultraestrutura , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Transporte de Elétrons/fisiologia , Proteínas de Membrana/química , Proteínas de Membrana/genética , Proteínas de Membrana/fisiologia , Dados de Sequência Molecular , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Estrutura Terciária de Proteína , Transporte Proteico/fisiologia , Alinhamento de Sequência , Transdução de Sinais
16.
FEMS Microbiol Lett ; 268(2): 171-7, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17328744

RESUMO

Phytoplasmas are noncultivable bacteria usually maintained in Catharanthus roseus shoots grown in vitro on MS medium with benzylaminopurine. The aim of our research was to examine the influence of indole-3-butyric acid (IBA) on C. roseus shoots infected with three different phytoplasma strains. Supplement of IBA in the medium supported plant growth, photosynthesis and remission of symptoms in all phytoplasma-infected shoots, but had no effect on the presence of EY-C and SA-I phytoplasma strains in tested tissue. However, HYDB phytoplasma was undetectable in approximately half of the tested shoots grown on the medium with IBA. After 1 year of IBA treatment, HYDB-infected periwinkle shoots were retransferred to the medium supplemented with benzylaminopurine. Some of the shoots showing remission of symptoms during the IBA treatment permanently escaped the infection and remained negative when tested for phytoplasma presence. This is the first report on the differential influence of plant growth regulators on phytoplasma-infected C. roseus shoots.


Assuntos
Antibacterianos/farmacologia , Catharanthus/microbiologia , Ácidos Indolacéticos/farmacologia , Phytoplasma/efeitos dos fármacos , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas/farmacologia , Brotos de Planta/microbiologia , Fatores de Tempo , Técnicas de Cultura de Tecidos
17.
Biol Chem ; 386(8): 777-83, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16201873

RESUMO

We demonstrate that basic components of the plastid protein-import apparatus originally found in pea, Toc34, Toc159, and Tic110, are also conserved in evolutionarily younger gymnosperms. We show that multiple isoforms of the preprotein receptor Toc34 differentially accumulate in various stages of needle development, while the amounts of Toc159 drastically decrease during chloroplast morphogenesis. Spruce Toc34 and Toc159 receptors are able to recognise and interact with the angiosperm precursor of the Rubisco small subunit. Young proplastids found in closed buds contain a highly elevated number of protein translocation complexes equipped with only two types of outer envelope receptors, Toc159 and a 30-kDa Toc34-related protein. Photosystem II (PSII) can already be assembled in a fully functional complex at this very early stage of needle development, suggesting that no additional receptor isoforms are needed for translocation of all necessary PSII components. We conclude that the accumulation of evolutionarily conserved plastid preprotein translocation components is differentially regulated during spruce needle development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , GTP Fosfo-Hidrolases/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Picea/metabolismo , Proteínas de Plantas/metabolismo , Plastídeos/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores de Peptídeos/metabolismo , Transporte Biológico Ativo , Peso Molecular , Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/metabolismo , Picea/crescimento & desenvolvimento , Plastídeos/química , Especificidade por Substrato
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...