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1.
BMC Evol Biol ; 16: 71, 2016 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-27044655

RESUMO

BACKGROUND: Mixed dispersal syndromes have historically been regarded as a bet-hedging mechanism that enhances survivorship in unpredictable environments, ensuring that some propagules stay in the maternal environment while others can potentially colonize new sites. However, this entails paying the costs of both dispersal and non-dispersal. Propagules that disperse are likely to encounter unfavorable conditions, while non-dispersing propagules might form inbred populations of close relatives. Here, we investigate the conditions under which mixed dispersal syndromes emerge and are evolutionarily stable, taking into account the risks of both environmental unpredictability and inbreeding. RESULTS: Using mathematical and computational modeling, we show that high dispersal propensity is favored whenever environmental unpredictability is low and inbreeding depression high, whereas mixed dispersal syndromes are adaptive under high environmental unpredictability, more particularly if inbreeding depression is small. Although pure dispersal is frequently adaptive, mixed dispersal represents the optimal strategy under many different parameterizations of our models, indicating that this strategy is likely to be favored in a wide variety of contexts. Furthermore, monomorphic populations go inevitably extinct when environmental and genetic costs are high, whilst mixed strategies can maintain viable populations even under very extreme conditions. CONCLUSIONS: Our models support the hypothesis that the interplay between inbreeding depression and environmental unpredictability shapes dispersal syndromes, often resulting in mixed strategies. Moreover, mixed dispersal seems to facilitate persistence whenever conditions are critical or nearly critical for survival.


Assuntos
Endogamia , Lathyrus/genética , Modelos Biológicos , Dispersão de Sementes , Vicia/genética , Evolução Biológica , Simulação por Computador , Meio Ambiente , Lathyrus/fisiologia , Vicia/fisiologia
2.
Mol Plant Microbe Interact ; 28(12): 1281-7, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26422403

RESUMO

MgtE is predicted to be a Rhizobium leguminosarum channel and is essential for growth when both Mg²âº is limiting and the pH is low. N2was only fixed at 8% of the rate of wild type when the crop legume Pisum sativum was inoculated with an mgtE mutant of R. leguminosarum and, although bacteroids were present, they were few in number and not fully developed. R. leguminosarum MgtE was also essential for N2fixation on the native legume Vicia hirsuta but not when in symbiosis with Vicia faba. The importance of MgtE and the relevance of the contrasting phenotypes is discussed.


Assuntos
Proteínas de Bactérias/fisiologia , Canais Iônicos/fisiologia , Magnésio/metabolismo , Fixação de Nitrogênio/fisiologia , Rhizobium leguminosarum/fisiologia , Vicia/crescimento & desenvolvimento , Proteínas de Bactérias/metabolismo , Canais Iônicos/metabolismo , Magnésio/fisiologia , Vicia/microbiologia , Vicia/fisiologia
3.
J Plant Physiol ; 184: 37-48, 2015 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-26210320

RESUMO

Galactinol is the galactosyl donor for the biosynthesis of both the raffinose family oligosaccharides (RFOs) and galactosyl cyclitols (Gal-C). Its synthesis by galactinol synthase (GolS, EC 2.4.1.123) is the first committed step of the soluble α-D-galactosides biosynthetic pathway in orthodox seeds. The deposition of galactosides in seeds is suggested to be associated with desiccation tolerance (DT). In this work, for the first time, we cloned and characterized two Vicia hirsuta (L.) S.F. Gray galactinol synthase genes (VhGolS1, VhGolS2), analyzed galactinol synthase activity and measured the accumulation of galactosides of both sucrose and D-pinitol in relation to the acquisition of DT in developing seeds of this wild species. A developmentally induced increase of VhGolS1 expression preceded the rise of GolS activity in crude protein extract from maturing seeds, while the expression of the VhGolS2 gene remained low. GolS activity peaked just after the beginning of the maturation drying phase. The increase of GolS activity was not followed by galactinol accumulation, instead the high enzyme activity was related to high levels of galactose bound in soluble galactosides of the RFO and galactosyl pinitol series. Acquisition of DT coincided with an increase of VhGolS1 expression, high galactinol synthase activity and the accumulation of oligogalactosides in seeds. DT was positively correlated with the high content of soluble α-D-galactosides of both the RFO and galactosyl pinitol series as well as with the amount of galactose bound in these galactosides.


Assuntos
Secas , Galactosiltransferases/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Vicia/fisiologia , Sequência de Aminoácidos , Ciclitóis/metabolismo , Dessecação , Galactosídeos/metabolismo , Galactosiltransferases/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Dados de Sequência Molecular , Filogenia , Proteínas de Plantas/metabolismo , Rafinose/metabolismo , Sementes/metabolismo , Vicia/genética
4.
Environ Sci Pollut Res Int ; 20(8): 5405-15, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23417437

RESUMO

The presence of cyanotoxins, mainly microcystins (MCs), in surface freshwater represents a serious health risk to aquatic organisms living in the water body, as well as terrestrial animals and plants that are in contact with contaminated water. Consequently, the use of MCs contaminated water for irrigation represents a hazard for cultivated plants and could induce severe economical losses due to crops' yield reduction. The experimental approach undertaken in this work was exposing Vicia faba seedlings (inoculated with a Rhizobium strain resistant to MCs), to water supplemented with cyanobacterial crude extract containing total microcystins at a concentration of 50 and 100 µg/L (environmental relevant concentrations of MCs dissolved in the raw irrigation water from Lalla Takerkoust Lake-Marrakesh region). After chronic MCs exposure (2 months), biological and physiological parameters (plant growth, nitrogen uptake, mineral assimilation, and oxidative defense mechanisms) were evaluated. The results obtained showed evidence that chronic exposure to cyanobacterial bloom extract containing MCs strongly affected the physiological and biological plants activities; reduction of dry matter, photosynthetic activity, nodule number, and nitrogen assimilation. At the same time, an increase of oxidative stress was observed, as deduced from a significant increase of the activities of peroxidase, catalase, polyphenoloxidase, and phenylalanine ammonia lyase in leaves, roots, and nodules of faba bean plants exposed to cyanotoxins, especially at 100 µg/L of MCs. This experimentation constitutes a simulation of the situation related to cyanotoxins chronic exposure of seedlings-plants via the contaminated irrigation water. For this reason, once should take into consideration the possibility of contamination of agricultural crops and the quality of irrigation water should be by the way monitored for cyanotoxins biohazard.


Assuntos
Misturas Complexas/farmacologia , Cianobactérias , Microcistinas/farmacologia , Rhizobium/efeitos dos fármacos , Simbiose/efeitos dos fármacos , Vicia/efeitos dos fármacos , Catalase/metabolismo , Catecol Oxidase/metabolismo , Peroxidase/metabolismo , Fenóis/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Rhizobium/fisiologia , Vicia/fisiologia
5.
Mol Plant ; 5(3): 601-10, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22402260

RESUMO

Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP-tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen peroxide, or sodium hydrogen carbonate. Guard cells kept in the dark (closed stomata) showed increases in microtubule structures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrangement must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin disrupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not disrupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.


Assuntos
Arabidopsis/citologia , Arabidopsis/fisiologia , Microtúbulos/metabolismo , Estômatos de Plantas/citologia , Vicia/citologia , Vicia/fisiologia , Ácido Abscísico/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/efeitos da radiação , Escuridão , Dinitrobenzenos/farmacologia , Fluorescência , Proteínas de Fluorescência Verde/metabolismo , Microtúbulos/efeitos dos fármacos , Microtúbulos/efeitos da radiação , Paclitaxel/farmacologia , Estômatos de Plantas/fisiologia , Estômatos de Plantas/efeitos da radiação , Transpiração Vegetal/efeitos dos fármacos , Plantas Geneticamente Modificadas , Proteínas Recombinantes de Fusão/metabolismo , Plântula/efeitos dos fármacos , Plântula/fisiologia , Plântula/efeitos da radiação , Sulfanilamidas/farmacologia , Tubulina (Proteína)/metabolismo , Vicia/efeitos dos fármacos , Vicia/efeitos da radiação
6.
Plant Cell Environ ; 35(8): 1419-27, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22348276

RESUMO

In the legume phloem, sieve element occlusion (SEO) proteins assemble into Ca(2+)-dependent contractile bodies. These forisomes presumably control phloem transport by forming reversible sieve tube plugs. This function, however, has never been directly demonstrated, and appears questionable as forisomes were reported to be too small to plug sieve tubes, and failed to block flow efficiently in artificial microchannels. Moreover, plugs of SEO-related proteins in Arabidopsis sieve tubes do not affect phloem translocation. We improved existing procedures for forisome isolation and storage, and found that the degree of Ca(2+)-driven deformation that is possible in forisomes of Vicia faba, the standard object of earlier research, has been underestimated substantially. Forisomes deform particularly strongly under reducing conditions and high sugar concentrations, as typically found in sieve tubes. In contrast to our previous inference, Ca(2+)-inducible forisome swelling certainly seems sufficient to plug sieve tubes. This conclusion was supported by 3D-reconstructions of forisome plugs in Canavalia gladiata. For a direct test, we built microfluidics chips with artificial sieve tubes. Using fluorescent dyes to visualize flow, we demonstrated the complete blockage of these biomimetic microtubes by Ca(2+)-induced forisome plugs, and concluded by analogy that forisomes are capable of regulating phloem flow in vivo.


Assuntos
Arabidopsis/fisiologia , Vicia/fisiologia , Microfluídica , Floema/fisiologia
7.
Ecotoxicol Environ Saf ; 78: 281-6, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22154778

RESUMO

Sulfur dioxide (SO(2)) induced nuclear condensation and nuclear fragmentation and rapid loss of guard cell viability in detached epidermis of Vicia leaves at concentrations of 1 mM and higher (3 h exposure). Caspase inhibitors Z-Asp-CH(2)-DCB (0.1 mM) and TLCK (0.1 mM) markedly suppressed SO(2)-induced cell death. The typical nuclear morphological changes and the inhibition effects of caspase inhibitors suggest the activation of a programmed cell death (PCD) pathway. SO(2)-induced cell death can be blocked by either antioxidants (0.1 mM AsA or 200 U/mL CAT) or Ca(2+) antagonists (0.1mM EGTA or LaCl(3)). AsA and CAT also blocked SO(2)-induced ROS production and [Ca(2+)](cyt) increase. However, EGTA and LaCl(3) can inhibit SO(2)-induced [Ca(2+)](cyt) increase, but cannot suppress SO(2)-induced ROS production. Our results indicate that high concentrations of SO(2) induce guard cell death via a PCD pathway through ROS mediating [Ca(2+)](cyt) elevation, which causes harmful effects to plants.


Assuntos
Poluentes Atmosféricos/toxicidade , Dióxido de Enxofre/toxicidade , Vicia/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Cálcio/metabolismo , Epiderme Vegetal/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Vicia/fisiologia
8.
Ann Bot ; 108(5): 877-84, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21831855

RESUMO

Background and Aims The presence of co-flowering species can alter pollinator foraging behaviour and, in turn, positively or negatively affect the reproductive success of the focal species. Such interactions were investigated between a focal species, Pedicularis monbeigiana, and a co-flowering species, Vicia dichroantha, which was mediated by behaviour alteration of the shared bumble-bee pollinator. Methods Floral display size and floral colour change of P. monbeigiana were compared between pure (P. monbeigiana only) and mixed (P. monbeigiana and V. dichroantha) plots in two populations. Pollinator visitation rates, interspecific floral switching and successive within-plant pollinator visits were recorded. In addition, supplemental pollination at plant level was performed, and the fruit set and seed set were analysed in pure and mixed plots with different densities of P. monbeigiana. Key Results Pollinator visitation rates were dramatically higher in mixed plots than in pure plots. The higher pollinator visitation rates were recorded in both low- and high-density plots. In particular, successive flower visits within an individual plant were significantly lower in mixed plots. Supplemental pollination significantly increased fruit set and seed set of individuals in pure plots, while it only marginally increased seed set per fruit of plants in mixed plots. Conclusions The presence of V. dichroantha can facilitate pollination and increase female reproductive success of P. monbeigiana via both quantity (mitigating pollinator limitation) and quality (reducing geitonogamy) effects. This study suggests that successive pollinator movements among flowers within a plant, as well as pollinator visitation rates and interspecific flower switching, may be important determinants of the direction and mechanisms of interaction between species.


Assuntos
Abelhas , Pedicularis/fisiologia , Polinização , Vicia/fisiologia , Animais , China , Flores/anatomia & histologia , Flores/crescimento & desenvolvimento , Frutas/crescimento & desenvolvimento , Pedicularis/anatomia & histologia , Pedicularis/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Vicia/anatomia & histologia , Vicia/crescimento & desenvolvimento
9.
J Plant Res ; 124(4): 477-87, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21706139

RESUMO

Abscisic acid (ABA) signaling mechanisms have been studied in a broad variety of plant species using complementary analyses, taking advantage of different methodologies suitable for each plant species. Early studies on ABA biosynthesis using Solanum lycopersicum mutants suggested an importance of ABA synthesis in stomatal closure. To understand ABA signaling in guard cells, cellular, biochemical and electrophysiological studies in Vicia faba and Commelina communis have been conducted, providing fundamental knowledge that was further reconfirmed by molecular genetic studies of Arabidopsis. In this article, examples of stomatal studies in several plants and prospects in ABA research are discussed.


Assuntos
Ácido Abscísico/metabolismo , Commelina/fisiologia , Estômatos de Plantas/fisiologia , Transdução de Sinais , Vicia/fisiologia , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Dióxido de Carbono/metabolismo , Membrana Celular/metabolismo , Commelina/genética , Germinação , Células do Mesofilo/metabolismo , Estômatos de Plantas/genética , Sementes/metabolismo , Vicia/genética
10.
Ann Bot ; 107(4): 709-15, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21262794

RESUMO

BACKGROUND: Fluorescent tagging of nodule bacteria forming symbioses with legume host plants represents a tool for vital tracking of bacteria inside the symbiotic root nodules and monitoring changes in gene activity. The constitutive expression of heterologous fluorescent proteins, such as green fluorescent protein (GFP), also allows screening for nodule occupancy by a particular strain. Imaging of the fluorescence signal on a macro-scale is associated with technical problems due to the robustness of nodule tissues and a high level of autofluorescence. SCOPE: These limitations can be reduced by the use of a model species with a fine root system, such as Vicia tetrasperma. Further increases in the sensitivity and specificity of the detection and in image resolution can be attained by the use of a fluorescence scanner. Compared with the standard CCD-type cameras, the availability of a laser source of a specified excitation wavelength decreases non-specific autofluorescence while the photomultiplier tubes in emission detection significantly increase sensitivity. The large scanning area combined with a high resolution allow us to visualize individual nodules during the scan of whole root systems. Using a fluorescence scanner with excitation wavelength of 488 nm, a band-pass specific emission channel of 532 nm and a long-pass background channel of 555 nm, it was possible to distinguish nodules occupied by a rhizobial strain marked with one copy of cycle3 GFP from nodules colonized by the wild-type strain. CONCLUSIONS: The main limitation of the current plant model and GFP with the wild-type emission peak at 409 nm is a sharp increase in root autofluorescence below 550 nm. The selectivity of the technique can be enhanced by the use of red-shifted fluorophores and the contrasting labelling of the variants, provided that the excitation (482 nm) and emission (737 nm) maxima corresponding to root chlorophyll are respected.


Assuntos
Modelos Biológicos , Nódulos Radiculares de Plantas/fisiologia , Espectrometria de Fluorescência/instrumentação , Simbiose/fisiologia , Vicia/fisiologia
11.
J Bacteriol ; 191(12): 4002-14, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19376875

RESUMO

Rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (Pisum sativum) and vetch (Vicia cracca), and has been widely used as a model to study nodule biochemistry. To understand the complex biochemical and developmental changes undergone by R. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate, and acetoacetate) and then compared to bacteroids. Bacteroid metabolism is essentially that of dicarboxylate-grown cells (i.e., induction of dicarboxylate transport, gluconeogenesis and alanine synthesis, and repression of sugar utilization). The decarboxylating arm of the tricarboxylic acid cycle is highly induced, as is gamma-aminobutyrate metabolism, particularly in bacteroids from early (7-day) nodules. To investigate bacteroid development, gene expression in bacteroids was analyzed at 7, 15, and 21 days postinoculation of peas. This revealed that bacterial rRNA isolated from pea, but not vetch, is extensively processed in mature bacteroids. In early development (7 days), there were large changes in the expression of regulators, exported and cell surface molecules, multidrug exporters, and heat and cold shock proteins. fix genes were induced early but continued to increase in mature bacteroids, while nif genes were induced strongly in older bacteroids. Mutation of 37 genes that were strongly upregulated in mature bacteroids revealed that none were essential for nitrogen fixation. However, screening of 3,072 mini-Tn5 mutants on peas revealed previously uncharacterized genes essential for nitrogen fixation. These encoded a potential magnesium transporter, an AAA domain protein, and proteins involved in cytochrome synthesis.


Assuntos
Ervilhas/microbiologia , Rhizobium leguminosarum/genética , Simbiose , Transcrição Genética , Vicia/microbiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Ervilhas/fisiologia , Rhizobium leguminosarum/crescimento & desenvolvimento , Rhizobium leguminosarum/fisiologia , Nódulos Radiculares de Plantas/microbiologia , Nódulos Radiculares de Plantas/fisiologia , Especificidade da Espécie , Vicia/fisiologia
12.
Folia Microbiol (Praha) ; 53(2): 139-46, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18500633

RESUMO

In rhizobial symbiosis with legume plant hosts, the symbiotic tissue in the root nodules of indeterminate type is localized to the basal part of the nodule where the symbiotic zones contain infected cells (IC) interspersed with uninfected cells (UC) that are devoid of rhizobia. Although IC are easily distinguished in nodule sections using standard histochemical techniques, their observation in intact nodules is hampered by nodule tissue characteristics. Tagging of Rhizobium leguminosarum bv. viciae strain 128C30 with a constitutively expressed gene for green fluorescent protein (nonshifted mutant form cycle3) in combination with the advantages of the tiny nodules formed by Vicia tetrasperma (L.) SCHREB . allowed for vital observation of symbiotic tissue using fluorescence microscopy. Separation of a red-shifted background channel and digital image stacking along z-axis enabled us to construct a nodule image in a classical fluorescence microscopy of nodules exceeding 1 mm in diameter. In parallel, visualization of nodule bacteria inside the symbiotic tissue by confocal microscopy at the excitation wavelength 488 nm clearly distinguished IC/UC pattern in the nodule virtual sections and revealed red-shifted fluorescence of nonrhizobial origin. This signal was located on the periphery of IC and increased with their degradation, thus suggesting accumulation of secondary metabolites, presumably flavonoids. The simultaneous detection of bacteria and secondary metabolites can be used for monitoring changes to intact nodule physiology in the model legumes. The advantage of V. tetrasperma as a suggested laboratory model for pea cross-inoculation group has been demonstrated.


Assuntos
Proteínas de Fluorescência Verde/metabolismo , Rhizobium leguminosarum/fisiologia , Nódulos Radiculares de Plantas/fisiologia , Microbiologia do Solo , Simbiose , Vicia/fisiologia , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/genética , Microscopia de Fluorescência , Rhizobium leguminosarum/química , Rhizobium leguminosarum/citologia , Rhizobium leguminosarum/genética , Nódulos Radiculares de Plantas/química , Nódulos Radiculares de Plantas/microbiologia , Vicia/química , Vicia/citologia , Vicia/microbiologia
13.
Mol Plant ; 1(2): 347-58, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19825544

RESUMO

There is now growing evidence that membrane vesicle trafficking proteins, especially of the superfamily of SNAREs, are critical for cellular signalling in plants. Work from this laboratory first demonstrated that a soluble, inhibitory (dominant-negative) fragment of the SNARE NtSyp121 blocked K+ and Cl- channel responses to the stress-related hormone abscisic acid (ABA), but left open a question about functional impacts on signal intermediates, especially on Ca2+-mediated signalling events. Here, we report one mode of action for the SNARE mediated directly through alterations in Ca2+ channel gating and its consequent effects on cytosolic-free [Ca2+] ([Ca2+]i) elevation. We find that expressing the same inhibitory fragment of NtSyp121 blocks ABA-evoked stomatal closure, but only partially suppresses stomatal closure in the presence of the NO donor, SNAP, which promotes [Ca2+]i elevation independently of the plasma membrane Ca2+ channels. Consistent with these observations, Ca2+ channel gating at the plasma membrane is altered by the SNARE fragment in a manner effective in reducing the potential for triggering a rise in [Ca2+]i, and we show directly that its expression in vivo leads to a pronounced suppression of evoked [Ca2+]i transients. These observations offer primary evidence for the functional coupling of the SNARE with Ca2+ channels at the plant cell plasma membrane and, because [Ca2+]i plays a key role in the control of K+ and Cl- channel currents in guard cells, they underscore an important mechanism for SNARE integration with ion channel regulation during stomatal closure.


Assuntos
Ácido Abscísico/farmacologia , Cálcio/metabolismo , Ativação do Canal Iônico/fisiologia , Proteínas SNARE/fisiologia , Vicia/fisiologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/fisiologia , Dexametasona/farmacologia , Ativação do Canal Iônico/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Plantas Geneticamente Modificadas/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Tabaco/efeitos dos fármacos , Tabaco/fisiologia , Vicia/efeitos dos fármacos
14.
Plant Cell Physiol ; 48(5): 715-23, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17389607

RESUMO

Recent evidence suggests that nitric oxide (NO) acts as an intermediate of ABA signal transduction for stomatal closure. However, NO's effect on stomatal opening is poorly understood even though both opening and closing activities determine stomatal aperture. Here we show that NO inhibits stomatal opening specific to blue light, thereby stimulating stomatal closure. NO inhibited blue light-specific stomatal opening but not red light-induced opening. NO inhibited both blue light-induced H(+) pumping and H(+)-ATPase phosphorylation. The NO scavenger 2-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) restored all these inhibitory effects. ABA and hydrogen peroxide (H(2)O(2)) inhibited all of these blue light-specific responses in a manner similar to NO. c-PTIO partially restored the ABA-induced inhibition of all of these opening responses but did not restore inhibition of the responses by H(2)O(2). ABA, H(2)O(2) and NO had slight inhibitory effects on the phosphorylation of phototropins, which are blue light receptors in guard cells. NO inhibited neither fusicoccin-induced H(+) pumping in guard cells nor H(+) transport by H(+)-ATPase in the isolated membranes. From these results, we conclude that both NO and H(2)O(2) inhibit blue light-induced activation of H(+)-ATPase by inhibiting the component(s) between phototropins and H(+)-ATPase in guard cells and stimulate stomatal closure by ABA.


Assuntos
Ácido Abscísico/farmacologia , Luz , Doadores de Óxido Nítrico/farmacologia , Vicia/fisiologia , Óxidos N-Cíclicos/farmacologia , Depuradores de Radicais Livres/farmacologia , Peróxido de Hidrogênio/farmacologia , Imidazóis/farmacologia , Óxido Nítrico/metabolismo , Óxido Nítrico/fisiologia , Fosforilação/efeitos dos fármacos , Epiderme Vegetal/citologia , Epiderme Vegetal/fisiologia , Proteínas de Plantas/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Transdução de Sinais , Vicia/efeitos dos fármacos , Vicia/efeitos da radiação
15.
Environ Pollut ; 145(3): 850-60, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16815612

RESUMO

We studied the effects of elevated O3 (40-50 ppb) and CO2 (+100 ppm) alone and in combination on the growth onset, relative chlorophyll meter values, and reproductive development of meadow species grown in ground-planted mesocosms using open-top chambers. The 3-year study was conducted in the summers of 2002-2004. Elevated O3 decreased the early season coverage of plant communities and delayed the flowering of Campanula rotundifolia and Vicia cracca. The relative chlorophyll meter values of Fragaria vesca leaves were decreased by O3. Ozone also reduced the overall number of produced flowers, but as far as individual species were concerned, O3 had significant effects only on Campanula rotundifolia. In the case of Fragaria vesca, O3 decreased the fresh weight of individual berries. The effects of CO2 were less pronounced, and CO2 generally did not ameliorate the negative effects of O3. Changes in reproduction may affect the long-term fate of the whole community.


Assuntos
Poluentes Atmosféricos/toxicidade , Dióxido de Carbono/toxicidade , Magnoliopsida/fisiologia , Ozônio/toxicidade , Agrostis/fisiologia , Poluentes Atmosféricos/análise , Campanulaceae/fisiologia , Dióxido de Carbono/análise , Clorofila/análise , Clima , Ecossistema , Exposição Ambiental/efeitos adversos , Monitoramento Ambiental/métodos , Flores/fisiologia , Fragaria/fisiologia , Frutas/fisiologia , Magnoliopsida/crescimento & desenvolvimento , Oxidantes Fotoquímicos/análise , Oxidantes Fotoquímicos/toxicidade , Ozônio/análise , Poaceae/crescimento & desenvolvimento , Poaceae/fisiologia , Ranunculus/fisiologia , Reprodução/fisiologia , Trifolium/fisiologia , Vicia/fisiologia
16.
J Exp Bot ; 55(401): 1423-31, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15133055

RESUMO

Thermal imaging is a potential tool for estimating plant temperature, which can be used as an indicator of stomatal closure and water deficit stress. In this study, a new method for processing and analysing thermal images was developed. By using remote sensing software, the information from thermal and visible images was combined, the images were classified to identify leaf area and sunlit and shaded parts of the canopy, and the temperature statistics for specific canopy components were calculated. The method was applied to data from a greenhouse water-stress experiment of Vicia faba L. and to field data for Vitis vinifera L. Vaseline-covered and water-sprayed plants were used as dry and wet references, respectively, and two thermal indices, based on temperature differences between the canopy and reference surfaces, were calculated for single Vicia faba plants. The thermal indices were compared with measured stomatal conductance. The temperature distributions of sunlit and shaded leaf area of Vitis vinifera canopies from natural rainfall and irrigation treatments were compared. The present method provides two major improvements compared with earlier methods for calculating thermal indices. First, it allows more accurate estimation of the indices, which are consequently more closely related to stomatal conductance. Second, it gives more accurate estimates of the temperature distribution of the shaded and sunlit parts of canopy, and, unlike the earlier methods, makes it possible to quantify the relationship between temperature variation and stomatal conductance.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Vicia/fisiologia , Vitis/fisiologia , Água/fisiologia , Algoritmos , Modelos Biológicos , Epiderme Vegetal/fisiologia , Folhas de Planta/fisiologia , Estresse Mecânico , Temperatura Ambiente
18.
Plant Cell Physiol ; 43(11): 1359-65, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12461136

RESUMO

Blue light (BL) activates the plasma membrane H(+)-ATPase via phosphorylation of the C-terminus with concomitant binding of 14-3-3 protein to the terminus in stomatal guard cells. However, the binding site and role of 14-3-3 protein in this physiological response have not been elucidated. We investigated the above using synthetic phosphopeptides designed from the C-terminus of Vicia H(+)-ATPase (isoform 1; VHA1). The presence of KGLDIDTIQQHYphospho-T(950)V peptide (P-950) prevented binding of 14-3-3 protein to the phosphorylated H(+)-ATPase. Dephosphorylated P-950 and other phosphopeptides, including typical phosphorylation sites in the C-terminus, had no effect on the binding. Incubation of BL-activated plasma membrane H(+)-ATPase with P-950 dissociated the 14-3-3 protein from the H(+)-ATPase without affecting phosphorylation levels and decreased the H(+)-ATPase activity. By contrast, incubation of P-950 with the activated H(+)-ATPase from fusicoccin-treated guard-cell protoplasts neither dissociated the 14-3-3 protein nor decreased the H(+)-ATPase activity. These results indicate that BL induces phosphorylation on threonine residue (Thr(950)) in the C-terminus of H(+)-ATPase, and that the binding of 14-3-3 to this site is required for the activation of H(+)-ATPase in stomatal guard cells.


Assuntos
Epiderme Vegetal/fisiologia , ATPases Translocadoras de Prótons/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Vicia/fisiologia , Proteínas 14-3-3 , Sequência de Aminoácidos , Membrana Celular/efeitos dos fármacos , Membrana Celular/fisiologia , Membrana Celular/efeitos da radiação , Glicosídeos/farmacologia , Luz , Dados de Sequência Molecular , Fosforilação , Pigmentos Biológicos/farmacologia , Epiderme Vegetal/efeitos dos fármacos , Epiderme Vegetal/efeitos da radiação , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/efeitos da radiação , Homologia de Sequência de Aminoácidos , Treonina/metabolismo , Tirosina 3-Mono-Oxigenase/antagonistas & inibidores , Tirosina 3-Mono-Oxigenase/química , Vicia/efeitos da radiação
19.
Plant Physiol ; 130(3): 1436-42, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12428008

RESUMO

A method is described for continuous, nondestructive analysis of xylem-borne mineral nutrients in intact transpiring plants. The method uses the xylem-feeding insect the meadow spittlebug (Philaenus spumarius L. [Homoptera: Cercopidae]). This insect will feed from a wide range of plant species and organs. Insect excreta can be collected at all times of the day and night, and its mineral ion content can be analyzed rapidly, and without purification, by ion chromatography. The excreta will have a mineral content virtually identical to that of xylem sap. Cages suitable for containing the insects and collecting excreta from any desired location on plants in both laboratory and greenhouse are described. Even in the greenhouse, evaporation had only a minor effect on the sample ion content. Example results are presented which illustrate dynamics, over several days, in the xylem concentrations of sodium (Na(+)), potassium (K(+)), NH(4)(+), magnesium (Mg(2+)), calcium (Ca(2+)), chloride (Cl(-)), NO(3)(-), PO(4)(3-), and SO(4)(2-). These data were collected from young plants growing in pots of compost in the laboratory and from fully mature pepper (Capsicum annuum L. cv Bellboy) plants growing in hydroponics (rockwool) in the greenhouse. This method should facilitate studies of macronutrient uptake and transport in a range of plants and environments.


Assuntos
Insetos/fisiologia , Transpiração Vegetal/fisiologia , Plantas/metabolismo , Animais , Cálcio/metabolismo , Capsicum/metabolismo , Capsicum/parasitologia , Capsicum/fisiologia , Cloretos/metabolismo , Cromatografia por Troca Iônica , Colorimetria , Comportamento Alimentar/fisiologia , Conteúdo Gastrointestinal/química , Íons/análise , Íons/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/parasitologia , Lycopersicon esculentum/fisiologia , Magnésio/metabolismo , Nitratos/metabolismo , Fosfatos/metabolismo , Caules de Planta/fisiologia , Plantas/parasitologia , Potássio/metabolismo , Compostos de Amônio Quaternário/metabolismo , Sódio/metabolismo , Sulfatos/metabolismo , Vicia/metabolismo , Vicia/parasitologia , Vicia/fisiologia
20.
Plant Cell ; 14(10): 2399-412, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12368494

RESUMO

Phosphatidylinositol (PI) metabolism plays a central role in signaling pathways in both animals and higher plants. Stomatal guard cells have been reported to contain PI 3-phosphate (PI3P) and PI 4-phosphate (PI4P), the products of PI 3-kinase (PI3K) and PI 4-kinase (PI4K) activities. In this study, we tested the roles of PI3P and PI4P in stomatal movements. Both wortmannin (WM) and LY294002 inhibited PI3K and PI4K activities in guard cells and promoted stomatal opening induced by white light or the circadian clock. WM and LY294002 also inhibited stomatal closing induced by abscisic acid (ABA). Furthermore, overexpression in guard cells of GFP:EBD (green fluorescent protein:endosome binding domain of human EEA1) or GFP:FAPP1PH (PI-four-P adaptor protein-1 pleckstrin homology domain), which bind to PI3P and PI4P, respectively, increased stomatal apertures under darkness and white light and partially inhibited stomatal closing induced by ABA. The reduction in ABA-induced stomatal closing with reduced levels of PI monophosphate seemed to be attributable, at least in part, to impaired Ca(2+) signaling, because WM and LY294002 inhibited ABA-induced cytosolic Ca(2+) increases in guard cells. These results suggest that PI3P and PI4P play an important role in the modulation of stomatal closing and that reductions in the levels of functional PI3P and PI4P enhance stomatal opening.


Assuntos
Fosfatos de Fosfatidilinositol/metabolismo , Epiderme Vegetal/fisiologia , Folhas de Planta/fisiologia , 1-Fosfatidilinositol 4-Quinase/metabolismo , Ácido Abscísico/farmacologia , Androstadienos/farmacologia , Arabidopsis/fisiologia , Proteínas Sanguíneas/química , Proteínas Sanguíneas/metabolismo , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Cromonas/farmacologia , Ritmo Circadiano/efeitos dos fármacos , Escuridão , Endossomos/química , Endossomos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Proteínas de Fluorescência Verde , Luz , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Morfolinas/farmacologia , Fosfatidilinositol 3-Quinases/antagonistas & inibidores , Fosfatidilinositol 3-Quinases/metabolismo , Fosfatos de Fosfatidilinositol/antagonistas & inibidores , Fosfoproteínas/química , Fosfoproteínas/metabolismo , Epiderme Vegetal/citologia , Folhas de Planta/citologia , Ligação Proteica/efeitos dos fármacos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , Vicia/fisiologia , Wortmanina
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