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1.
Int J Mol Sci ; 22(16)2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34445145

RESUMO

The main goal of growing plants under various photoperiods is to optimize photosynthesis for using the effect of day length that often acts on plants in combination with biotic and/or abiotic stresses. In this study, Brassica juncea plants were grown under four different day-length regimes, namely., 8 h day/16 h night, 12 h day/12 h night, 16 h day/8 h night, and continuous light, and were infected with a necrotrophic fungus Alternaria brassicicola. The development of necroses on B. juncea leaves was strongly influenced by leaf position and day length. The largest necroses were formed on plants grown under a 16 h day/8 h night photoperiod at 72 h post-inoculation (hpi). The implemented day-length regimes had a great impact on leaf morphology in response to A. brassicicola infection. They also influenced the chlorophyll and carotenoid contents and photosynthesis efficiency. Both the 1st (the oldest) and 3rd infected leaves showed significantly higher minimal fluorescence (F0) compared to the control leaves. Significantly lower values of other investigated chlorophyll a fluorescence parameters, e.g., maximum quantum yield of photosystem II (Fv/Fm) and non-photochemical quenching (NPQ), were observed in both infected leaves compared to the control, especially at 72 hpi. The oldest infected leaf, of approximately 30% of the B. juncea plants, grown under long-day and continuous light conditions showed a 'green island' phenotype in the form of a green ring surrounding an area of necrosis at 48 hpi. This phenomenon was also reflected in changes in the chloroplast's ultrastructure and accelerated senescence (yellowing) in the form of expanding chlorosis. Further research should investigate the mechanism and physiological aspects of 'green islands' formation in this pathosystem.


Assuntos
Alternaria/patogenicidade , Mostardeira/microbiologia , Mostardeira/fisiologia , Necrose/microbiologia , Necrose/patologia , Fotossíntese/fisiologia , Doenças das Plantas/microbiologia , Carotenoides/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Fluorescência , Mostardeira/metabolismo , Necrose/metabolismo , Fotoperíodo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia
2.
Plants (Basel) ; 10(1)2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33418897

RESUMO

Alnus viridis (Chaix) DC., green alder, is a fast-growing shrub that grows expansively in the European mountainside. In Poland, A. viridis naturally occurs only in the Bieszczady Mountains (south-eastern part of the country), above the upper forest border. In this study, we assessed the potential of green alder to expand in post-farming areas in the Bieszczady Mountains. We investigated the effects of topographical, climatic, and edaphic characteristics of four various study sites on the physiological and morphological properties of A. viridis leaves in order to answer the question whether the growth of plants in lower positions improves their physiological condition to such an extent that it increases the species invasiveness. This is the first comprehensive ecophysiological study of this species to be carried out in this part of Europe. The photochemical efficiency of PSII, the chlorophyll content, and leaf 13C and 15N discrimination were analyzed. On the basis of leaf radiation reflection, coefficients such as reflectance indices of anthocyanins, carotenoids, flavonoids (ARI2, CRI1, FRI), photochemical index of reflection (PRI), and the water band index (WBI) were calculated. We observed favorable physiological effects in A. viridis plants growing in locations below the upper forest border compared to plants growing in higher locations. As a result, A. viridis may become an invasive species and disturb the phytocoenotic balance of plant communities of the altitudinal zones in the Polish Western Carpathians.

3.
PLoS One ; 15(9): e0238448, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986744

RESUMO

Exposure to lead (Pb) can have serious toxic effects on the physiological and biochemical processes of plants. The chemical form of the metal determines the degree of its toxicity. In our research, we examined the effect of lead in the form of lead nitrate [Pb(NO3)2] and lead chloride (PbCl2) in concentrations of 12.5 mM and 25 mM on pine (Pinus sylvestris) seed germination. Nitrogen salt causes more severe changes than chloride salt. Increasing levels of electrolyte leakage, malondialdehyde, and hydrogen peroxide were detected during germination processes. The high levels of ROS lead to redox changes in the cell. We observed a reduction in the level of the reduced form of glutathione (GSH), and at the same time observed increased levels of the oxidised form of glutathione (GSSG) depending on the concentration and also the time of exposure to lead compounds. At the beginning of germination processes, the effective non-enzymatic activity of the antioxidant cycle was dominant, and at the late stage the enzymatic activity was noticed in the presence of Pb compounds. CAT activity significantly increased after Pb compound exposition.


Assuntos
Pinus sylvestris/metabolismo , Sementes/metabolismo , Antioxidantes/metabolismo , Germinação/efeitos dos fármacos , Glutationa/metabolismo , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/farmacologia , Chumbo/toxicidade , Malondialdeído/análise , Malondialdeído/farmacologia , Nitratos/toxicidade , Oxirredução , Pinus sylvestris/fisiologia , Espécies Reativas de Oxigênio , Sementes/fisiologia , Cloreto de Sódio
4.
Int J Mol Sci ; 21(17)2020 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-32887449

RESUMO

We studied changes in gas exchange, photochemical activity and the antioxidant system in cucumber leaves locally infected with Pseudomonas syringae pv lachrymans and in uninfected systemic ones. Infection-induced declined net photosynthesis rate and the related changes in transpiration rate, the intracellular CO2 concentration, and prolonged reduction in maximal PSII quantum yield (Fv/Fm), accompanied by an increase in non-photochemical quenching (NPQ), were observed only in the infected leaves, along with full disease symptom development. Infection severely affected the ROS/redox homeostasis at the cellular level and in chloroplasts. Superoxide dismutase, ascorbate, and tocopherol were preferentially induced at the early stage of pathogenesis, whereas catalase, glutathione, and the ascorbate-glutathione cycle enzymes were activated later. Systemic leaves retained their net photosynthesis rate and the changes in the antioxidant system were partly like those in the infected leaves, although they occurred later and were less intense. Re-balancing of ascorbate and glutathione in systemic leaves generated a specific redox signature in chloroplasts. We suggest that it could be a regulatory element playing a role in integrating photosynthesis and redox regulation of stress, aimed at increasing the defense capacity and maintaining the growth of the infected plant.


Assuntos
Antioxidantes/metabolismo , Cucumis sativus/fisiologia , Estresse Oxidativo , Fotossíntese , Folhas de Planta/fisiologia , Pseudomonas syringae/patogenicidade , Catalase/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Cloroplastos/microbiologia , Cucumis sativus/microbiologia , Glutationa/metabolismo , Oxirredução , Folhas de Planta/microbiologia , Superóxido Dismutase/metabolismo
5.
Physiol Plant ; 168(3): 601-616, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31145472

RESUMO

During the first 24 hours of infection, Alternaria brassicicola developmental parameters such as conidial germination, germ tubes and appressoria formation on each of the five mature Brassica juncea leaves, correlated with a leaf position showing stronger development of the pathogen on older leaves than on young ones. As a consequence of fungal development, the black spot disease was observed during 96 hours of infection on a macroscopic scale, as well as via confocal microscopy. Degradation of the chloroplast thylakoids and plastoglobule appearance during infection, followed by the decrease in chlorophyll a fluorescence parameters i.e. maximum quantum yield of PSII (Fv /Fm ), non-photochemical quenching (NPQ) and chlorophyll a:b ratio, have been observed. Also, after an initial increase of carbohydrates (glucose, fructose and sucrose), content far below the respective control values was found. The content of secondary metabolites such as flavonoids and glucosinolates increased in a leaf position-dependent manner in infected leaves, with a lower level in older leaves than in younger ones. Although, the total phenolic compounds (TPCs) content did not differ significantly in infected leaves compared to control leaves, TPCs level in both control and infected leaves was leaf position-dependent. To the best of our knowledge, this is the first report on leaf position-dependent effect on the B. juncea biochemical response to A. brassicicola infection.


Assuntos
Alternaria/patogenicidade , Morte Celular , Mostardeira/metabolismo , Mostardeira/microbiologia , Fotossíntese , Doenças das Plantas/microbiologia , Clorofila , Folhas de Planta/microbiologia , Metabolismo Secundário
6.
Int J Mol Sci ; 20(22)2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31698683

RESUMO

The quality and amount of yellow lupine yield depend on water availability. Water scarcity negatively affects germination, flowering, and pod formation, and thus introduction of an artificial irrigation system is needed. The aim of this study was to evaluate the influence of irrigation on the quality of yellow lupine seeds. Raining was applied with a semi-solid device with sprinklers during periods of greatest water demand. It was shown that watered plants produced seeds of lesser quality, having smaller size and weight. To find out why seeds of irrigated plants were of poor quality, interdisciplinary research at the cellular level was carried out. DNA cytophotometry evidenced the presence of nuclei with lower polyploidy in the apical zone of mature seeds. This may lead to formation of smaller cells and reduce depositing of storage materials. The electrophoretic and Fourier transform infrared spectroscopic analyses revealed differences in protein and cuticular wax profiles, while scanning electron microscopy and energy dispersive spectroscopy revealed, among various chemical elements, decreased calcium content in one of seed zones (near plumule). Seeds from irrigated plants showed slightly higher germination dynamics but growth rate of seedlings was slightly lower. The studies showed that irrigation of lupine affected seed features and their chemical composition, an ability to germination and seedlings growth.


Assuntos
Irrigação Agrícola , Lupinus/química , Sementes/química , 3,3'-Diaminobenzidina/metabolismo , Cotilédone/metabolismo , DNA de Plantas/genética , Germinação , Peróxido de Hidrogênio/análise , Meristema/metabolismo , Mitose , Proteínas de Plantas/metabolismo , Plântula/crescimento & desenvolvimento , Sementes/anatomia & histologia , Sementes/ultraestrutura , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier
7.
Int J Mol Sci ; 20(7)2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30925807

RESUMO

Seeds enable plant survival in harsh environmental conditions, and via seeds, genetic information is transferred from parents to the new generation; this stage provides an opportunity for sessile plants to settle in new territories. However, seed viability decreases over long-term storage due to seed aging. For the effective conservation of gene resources, e.g., in gene banks, it is necessary to understand the causes of decreases in seed viability, not only where the aging process is initiated in seeds but also the sequence of events of this process. Mitochondria are the main source of reactive oxygen species (ROS) production, so they are more quickly and strongly exposed to oxidative damage than other organelles. The mitochondrial antioxidant system is also less active than the antioxidant systems of other organelles, thus such mitochondrial 'defects' can strongly affect various cell processes, including seed aging, which we discuss in this paper.


Assuntos
Mitocôndrias/metabolismo , Estresse Oxidativo , Fenômenos Fisiológicos Vegetais , Sementes/fisiologia , Envelhecimento , Oxirredução , Espécies Reativas de Oxigênio/metabolismo
8.
Planta ; 249(6): 1731-1746, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30684036

RESUMO

MAIN CONCLUSION: While plant irrigation usually increases yield, irrigation also affects seed characteristics with respect to endoreplication level, chemical composition, number of carbonyl bands, and cuticular wax profiles. Seeds of sweet varieties of the narrow-leaved lupin have good nutritional properties; however, these plants are sensitive to water deficit. Irrigation improves lupin yield, but can affect seed characteristics. The purpose of the study was to evaluate irrigation influence on lupin seed features and their chemical composition. Morphological analyses showed worse quality of seeds from the irrigated plants, with regard to their size and weight. This was confirmed by cytophotometric analyses which revealed a lower DNA content in the nuclei of cells from the apical and basal regions of the irrigated seeds. The lower degree of polyploidy of the nuclei entails lower cell sizes and limited space for storage components. Fourier transform infrared spectroscopic analysis demonstrated that protein and cuticular wax profiles of the irrigated seeds were different from the control. The electrophoretic analyses indicated differences in protein profiles including changes in the proportion of lupin storage proteins. Among the various studied elements, only the nitrogen content decreased in the embryo axis of irrigated plants. Although germination dynamics of the irrigated seeds was higher, the seedlings' development rate was slightly lower than in the control. The hydrogen peroxide level in root meristem cells was higher during germination in the control suggesting its regulatory role in seed metabolism/signaling. Our study indicated that irrigation of lupin plant affected seed features and composition.


Assuntos
Irrigação Agrícola , Peróxido de Hidrogênio/metabolismo , Lupinus/fisiologia , Sementes/fisiologia , Cotilédone/genética , Cotilédone/crescimento & desenvolvimento , Cotilédone/fisiologia , Cotilédone/ultraestrutura , Endorreduplicação , Germinação , Lupinus/genética , Lupinus/crescimento & desenvolvimento , Lupinus/ultraestrutura , Meristema/genética , Meristema/crescimento & desenvolvimento , Meristema/fisiologia , Meristema/ultraestrutura , Microscopia Eletrônica de Varredura , Mitose , Proteínas de Armazenamento de Sementes , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Plântula/ultraestrutura , Sementes/genética , Sementes/crescimento & desenvolvimento , Sementes/ultraestrutura , Espectroscopia de Infravermelho com Transformada de Fourier
9.
PeerJ ; 5: e3989, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29109915

RESUMO

Background: Deficiency of available forms of phosphorus is common in most soils and causes reduction of crop plants growth and yield. Recently, model plants responses to phosphate (Pi) deficiency have been intensively studied. However, acclimation mechanisms of cereals like oat (Avena sativa L.), to low Pi stress remains not fully understood. Oat plants have been usually cultured on poor soils, with a low nutrient content, but their responses to such conditions are not well known, therefore the main goal of the study was to investigate the mechanisms that enable oat plants to grow under low Pi conditions. Methods: Four oat cultivars (A. sativa, cv. Arab, Krezus, Rajtar and Szakal) were grown for three weeks in a nutrient media with various P sources: inorganic-KH2PO4 (control), organic-phytate (PA) and with no phosphate (-P). The effects of Pi deficiency on the level of P, oat growth parameters, intensity of photosynthesis, plant productivity, root exudation ability, localization, activity and isoforms of acid phosphatases, enzymes involved in Pi mobilization, were estimated. In addition, the effect of mycorrhization on plant growth was also observed. Results: All studied oat cultivars grown on Pi-deficient media had significantly decreased Pi content in the tissues. Pi deficiency caused inhibition of shoot growth, but generally it did not affect root elongation; root diameter was decreased, root/shoot ratios increased, whereas PA plants showed a similar growth to control. Photosynthesis rate and productivity parameters decreased under low Pi nutrition, however, sugar content generally increased. Studied oat cultivars did not respond to low Pi via increased exudation of carboxylates from the roots, as pH changes in the growth media were not observed. Pi starvation significantly increased the activity of extracellular and intracellular acid phosphatases (APases) in comparison to the control plants. Three major APase isoforms were detected in oat tissues and the isoform pattern was similar in all studied conditions, usually with a higher level of one of the isoforms under Pi starvation. Generally no significant effects of mycorrhizal colonization on growth of oat cultivars were observed. Discussion: We postulated that acid phosphatases played the most important role in oat cultivars acclimation to Pi deficiency, especially extracellular enzymes involved in Pi acquisition from soil organic P esters. These APases are mainly located in the epidermis of young roots, and may be released to the rhizosphere. On the other hand, intracellular APases could be involved in fast Pi remobilization from internal sources. Our study showed that oat, in contrast to other plants, can use phytates as the sole source of P. The studied oat cultivars demonstrated similar acclimation mechanisms to Pi deficiency, however, depending on stress level, they can use different pools of acid phosphatases.

10.
J Plant Physiol ; 169(16): 1597-606, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22770419

RESUMO

Carbohydrate starvation of Vicia faba root meristems leads to readjustment of carbohydrate metabolism and blocks the cell cycle in two principal control points (PCP1/2). The cell cycle reactivation is possible after sucrose provision, although with a delay of about 12h. During this period, the cells are sensitive to 6-dimethylaminopurine (6-DMAP) and okadaic acid (OA), inhibitors of protein kinases and phosphatases, respectively. The aim of the present study was to investigate whether those inhibitors are involved in inhibition of cell cycle revival through interference with the activities of two sucrose-cleaving enzymes: sucrose synthase (SuSy; EC 2.4.1.13) and invertase (INV; EC 3.2.1.26). In sugar-starved cells, the in situ activity of both enzymes decreased significantly. Following supplementation of root meristems with sugar, INV remained inactive, but SuSy activity increased. Despite the lack of INV activity, glucose was present in meristem cells, but its content was low in cells treated with OA. In the latter case, the size of plastids was reduced, they had less starch, and Golgi structures were affected. In sugar-starved cells, SuSy activity was induced more by exogenous sucrose than by glucose. The sucrose-induced activity was strongly inhibited by OA (less by 6-DMAP) at early stages of regeneration, but not at the stages preceding DNA replication or mitotic activities. The results indicate that prolongation of regeneration and a marked decrease in the number of cells resuming proliferation (observed in previous studies) and resulting from the action of inhibitors, are correlated with the process of SuSy activation at the beginning of regeneration from sugar starvation.


Assuntos
Metabolismo dos Carboidratos , Inibidores Enzimáticos/farmacologia , Glucosiltransferases/metabolismo , Meristema/enzimologia , Vicia faba/enzimologia , Adenina/análogos & derivados , Adenina/farmacologia , Carboidratos/deficiência , Ciclo Celular , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glucose/metabolismo , Glucosiltransferases/antagonistas & inibidores , Meristema/efeitos dos fármacos , Meristema/ultraestrutura , Ácido Okadáico/farmacologia , Fosforilação , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/enzimologia , Raízes de Plantas/ultraestrutura , Plastídeos/efeitos dos fármacos , Plastídeos/enzimologia , Plastídeos/ultraestrutura , Polissacarídeos/metabolismo , Amido/metabolismo , Sacarose/metabolismo , Vicia faba/efeitos dos fármacos , Vicia faba/ultraestrutura , beta-Frutofuranosidase/antagonistas & inibidores , beta-Frutofuranosidase/metabolismo
11.
Physiol Plant ; 135(4): 342-50, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19335447

RESUMO

The plant cell cycle is equipped with two principal control points: PCP1 in G1 and PCP2 in G2 phase. These checkpoints can arrest the cell cycle in response to carbohydrate starvation, while sugar presence can revive the replication and mitotic activity. The process of cell cycle revival is strongly repressed by okadaic acid (OA) or 6-dimethylaminopurine (6-DMAP), inhibitors of specific protein phosphatases 1 or 2A or kinases (cyclin-dependent kinases), respectively. In the present study, it was investigated whether inhibition of cell cycle revival is performed through interference of the above-mentioned inhibitors with the metabolic pathway of sucrose applied to the cells. Changes of hexokinase (HK) and fructokinase (FK) activities, key enzymes of hexose metabolism, were analyzed in Vicia faba root meristem cells arrested in G1 and G2 phase by carbohydrate starvation as well as in those recovered with glucose or sucrose in the presence of OA or 6-DMAP. It was shown that in the sugar-starved cells, the activity of both enzymes decreased significantly. During cell regeneration with carbohydrates, the activity of HK was induced more by sucrose than by glucose, while FK remained inactive after glucose addition. Moreover, in situ investigation of the activities of HK and FK showed that OA-induced and 6-DMAP-induced repression of the cell cycle revival is connected with the interference of these drugs in the metabolic pathway of sucrose. It was also indicated that stronger OA-induced and 6-DMAP-induced inhibition of the replication and mitosis revival, at the early stages of sucrose regeneration, was correlated with the stronger influence of these inhibitors on HK and FK activities.


Assuntos
Frutoquinases/metabolismo , Hexoquinase/metabolismo , Meristema/enzimologia , Vicia faba/enzimologia , Adenina/análogos & derivados , Adenina/farmacologia , Metabolismo dos Carboidratos , Ciclo Celular/efeitos dos fármacos , Glucose/metabolismo , Meristema/citologia , Ácido Okadáico/farmacologia , Fosforilação , Sacarose/metabolismo
12.
J Plant Physiol ; 162(3): 343-53, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15832687

RESUMO

The effects of inorganic phosphate (Pi) status, light/dark and sucrose on expression of UDP-glucose pyrophosphorylase (UGPase) gene (Ugp), which is involved in sucrose/ polysaccharides metabolism, were investigated using Arabidopsis wild-type (wt) plants and mutants impaired in Pi and carbohydrate status. Generally, P-deficiency resulted in increased Ugp expression and enhanced UGPase activity and protein content, as found for wt plants grown on P-deficient and complete nutrient solution, as well as for pho1 (P-deficient) mutants. Ugp was highly expressed in darkened leaves of pho1, but not wt plants; daily light exposure enhanced Ugp expression both in wt and pho mutants. The pho1 and pho2 (Pi-accumulating) mutations had little or no effect on leaf contents of glucose and fructose, regardless of light/dark conditions, whereas pho1 plants had much higher levels of sucrose and starch in the dark than pho2 and wt plants. The Ugp was up-regulated when leaves were fed with sucrose in wt plants, but the expression in pho2 background was much less sensitive to sucrose supply than in wt and pho1 plants. Expression of Ugp in pgm1 and sex1 mutants (impaired in starch/sugar content) was not dependent on starch content, and not tightly correlated with soluble sugar status. Okadaic acid (OKA) effectively blocked the P-starvation and sucrose-dependent expression of Ugp in excised leaves, whereas staurosporine (STA) had only a small effect on both processes (especially in -P leaves), suggesting that P-starvation and sucrose effects on Ugp are transmitted by pathways that may share similar components with respect to their (in) sensitivity to OKA and STA. The results of this study suggest that Ugp expression is modulated by an interaction of signals derived from P-deficiency status, sucrose content and dark/light conditions, and that light/sucrose and P-deficiency may have additive effects on Ugp expression.


Assuntos
Arabidopsis/enzimologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fosfatos/deficiência , Sacarose/farmacologia , UTP-Glucose-1-Fosfato Uridililtransferase/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Metabolismo dos Carboidratos , Escuridão , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos da radiação , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz
14.
Planta ; 217(2): 184-92, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12783326

RESUMO

Transgenic plants of Arabidopsis thaliana Heynh., transformed with a bacterial beta-glucuronidase (GUS) gene under the control of the promoter of the small subunit (ApS) of ADP-glucose pyrophosphorylase (AGPase), exhibited GUS staining in leaves (including stomata), stems, roots and flowers. Cross-sections of stems revealed GUS staining in protoxylem parenchyma, primary phloem and cortex. In young roots, the staining was found in the root tips, including the root cap, and in vascular tissue, while the older root-hypocotyl axis showed prominent staining in the secondary phloem and paratracheary parenchyma of secondary xylem. The GUS staining co-localized with ApS protein, as found by tissue printing using antibodies against ApS. Starch was found only in cell and tissue types exhibiting GUS staining and ApS labelling, but not in all of them. For example, starch was lacking in the xylem parenchyma and secondary phloem of the root-hypocotyl axis. Sucrose potently activated ApS gene expression in leaves of wild-type (wt) plants, and in transgenic seedlings grown on sucrose medium where GUS activity was quantified with 4-methylumbelliferyl-beta-glucuronide as substrate. Okadaic acid, an inhibitor of protein phosphatases 1 and 2A, completely blocked expression of ApS in mature leaves of wt plants and prevented GUS staining in root tips and flowers of the transgenic plants, suggesting a similar signal transduction mechanism for ApS expression in various tissues. The data support the key role of AGPase in starch synthesis, but they also underlie the ubiquitous importance of the ApS gene for AGPase function in all organs/tissues of Arabidopsis.


Assuntos
Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Nucleotidiltransferases/genética , Ácido Okadáico/farmacologia , Regiões Promotoras Genéticas/genética , Amido/biossíntese , Arabidopsis/citologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Genes de Plantas/genética , Glucose-1-Fosfato Adenililtransferase , Glucuronidase/genética , Glucuronidase/metabolismo , Folhas de Planta , Plantas Geneticamente Modificadas , Sacarose/metabolismo , Regulação para Cima
15.
Biochim Biophys Acta ; 1579(1): 43-9, 2002 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-12401218

RESUMO

The lack of phosphorus in the nutrient medium increased the expression of rab18, an abscisic acid (ABA)-responsive gene, in leaves of Arabidopsis thaliana. The expression of this gene was also upregulated after feeding the excised leaves with D-mannose and sucrose for both wild-type (wt) and aba1 (ABA-deficient) mutant plants. For aba1 mutants, both the phosphate deficiency and sugar effects on rab18 were weaker than in wt plants, suggesting possible involvement of both ABA-dependent and ABA-independent components in signalling. Transgenic Arabidopsis plants with increased hexokinase (HXK) expression had a much higher sucrose-dependent level of rab18 mRNA, implying the HXK involvement in sensing/transmitting the sugar signal. Sucrose-related induction of rab18 was completely inhibited by okadaic acid (OKA), suggesting the involvement of specific protein phosphatase(s) in transduction of the sugar signal. The results suggest that rab18 is regulated via interaction of a plethora of signals, including ABA, sugar and phosphate deficiency, and that the sugar effect is transmitted via a HXK-pathway, involving OKA-sensitive component(s). The findings prompt caution in linking the expression of rab18 solely to ABA signalling.


Assuntos
Carboidratos/farmacologia , Fosfatos/deficiência , Transdução de Sinais , Ácido Abscísico , Proteínas de Arabidopsis , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Hexoquinase/farmacologia , Manose , Ácido Okadáico/farmacologia , Fosfatos/análise , Reguladores de Crescimento de Plantas , Folhas de Planta/química , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas , Proteínas rab de Ligação ao GTP
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