Página 1 dos resultados de 570 itens digitais encontrados em 0.007 segundos

Exogenous ornithine is an effective precursor and the delta-ornithine amino transferase pathway contributes to proline accumulation under high N recycling in salt-stressed cashew leaves

Almeida da Rocha, Iza Marineves; Vitorello, Victor Alexandre; Silva, Jamille Santos; Ferreira-Silva, Sergio Luiz; Viegas, Ricardo Almeida; Silva, Evandro Nascimento; Gomes Silveira, Joaquim Albenisio
Fonte: ELSEVIER GMBH, URBAN & FISCHER VERLAG; JENA Publicador: ELSEVIER GMBH, URBAN & FISCHER VERLAG; JENA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.64%
The role of the delta-ornithine amino transferase (OAT) pathway in proline synthesis is still controversial and was assessed in leaves of cashew plants subjected to salinity. The activities of enzymes and the concentrations of metabolites involved in proline synthesis were examined in parallel with the capacity of exogenous ornithine and glutamate to induce proline accumulation. Proline accumulation was best correlated with OAT activity, which increased 4-fold and was paralleled by NADH oxidation coupled to the activities of OAT and Delta(1)-pyrroline-5-carboxylate reductase (P5CR), demonstrating the potential of proline synthesis via OAT/P5C. Overall, the activities of GS. GOGAT and aminating GDH remained practically unchanged under salinity. The activity of P5CR did not respond to NaCl whereas Delta(1)-pyrroline-5-carboxylate dehydrogenase was sharply repressed by salinity. We suggest that if the export of P5C from the mitochondria to the cytosol is possible, its subsequent conversion to proline by P5CR may be important. In a time-course experiment, proline accumulation was associated with disturbances in amino acid metabolism as indicated by large increases in the concentrations of ammonia, free amino acids, glutamine, arginine and ornithine. Conversely...

Free proline accumulation in sugarcane under water restriction and spittlebug infestation

Guimarães, Eduardo Rossini; Mutton, Miguel Angelo; Mutton, Márcia Justino Rossini; Ferro, Maria Inês Tiraboschi; Ravaneli, Gisele Cristina; Silva, Jorge Alberto da
Fonte: Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ) Publicador: Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ)
Tipo: Artigo de Revista Científica Formato: 628-633
ENG
Relevância na Pesquisa
66.48%
A cigarrinha-das-raízes Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) tornou-se uma praga importante da cultura da cana-de-açúcar na região centro-sul do Brasil. Estratégias de controle têm sido desenvolvidas, mas os danos promovidos por essa praga e sua interação com a cana-de-açúcar ainda são pouco caracterizados. em altos níveis de infestação da praga, os sintomas nas plantas são muito semelhantes à restrição hídrica severa. Este trabalho foi conduzido com o objetivo de determinar se o estresse promovido pela infestação de ninfas de cigarrinha-das-raízes resulta em acúmulo de prolina livre, além de comparar dois genótipos de cana-de-açúcar quanto à tolerância ao déficit hídrico. Dois experimentos foram conduzidos em delineamento inteiramente casualizado, em esquema fatorial 2 x 2 x 4 com duas cultivares (SP80-1816 e RB72454), dois níveis de estresse (controle e dez ninfas por planta ou 50% de restrição hídrica) e quatro épocas. O déficit hídrico promovido por M. fimbriolata não resultou em acúmulo de prolina, ilustrando a existência de mecanismos distintos para a percepção do estresse hídrico promovido pela praga e pela variação no potencial osmótico nas células das raízes. A cultivar RB72454 acumula maiores teores de prolina livre...

Free proline accumulation in sugarcane under water restriction and spittlebug infestation

Guimarães,Eduardo Rossini; Mutton,Miguel Angelo; Mutton,Márcia Justino Rossini; Ferro,Maria Inês Tiraboschi; Ravaneli,Gisele Cristina; Silva,Jorge Alberto da
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
66.48%
Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) has become a key pest in the sugarcane (Saccharum officinarum) fields of center-south Brazil. Although some control technologies have shown to be efficient, the damage promoted by this spittlebug species and its interaction with sugarcane are poorly characterized. At high infestation levels the symptoms are similar to those of severe water restriction. This work was conducted to determine whether the stress promoted by spittlebug infestation can be measured in terms of free proline accumulation. The water restriction tolerance of two sugarcane genotypes was also compared. Two experiments were set up in a greenhouse and arranged in a completely randomized design in a 2 x 2 x 4 factorial, with two cultivars (SP80-1816 and RB72454), two stress levels (control and ten nymphs per plant or 50% water restriction), and four sampling dates. The water deficit caused by spittlebug nymphs sucking xylem sap does not result in proline accumulation, illustrating that there are different mechanisms to sense when the water deficit is caused by insect feeding or water potential variation in root cells. The cultivar RB72454 accumulates more free-proline, and the dry mass accumulation and stalk growth are less affected in this cultivar under water restriction. The levels of compatible solutes probably cannot be used to measure spittlebug infestation stress in sugarcane and RB72454 is more tolerant to water shortage than SP80-1816.

l-Proline Accumulation and Freeze Tolerance in Saccharomyces cerevisiae Are Caused by a Mutation in the PRO1 Gene Encoding γ-Glutamyl Kinase

Morita, Yuko; Nakamori, Shigeru; Takagi, Hiroshi
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2003 EN
Relevância na Pesquisa
46.42%
We previously isolated a mutant which showed a high tolerance to freezing that correlated with higher levels of intracellular l-proline derived from l-proline analogue-resistant mutants. The mutation responsible for the analogue resistance and l-proline accumulation was a single nuclear dominant mutation. By introducing the mutant-derived genomic library into a non-l-proline-utilizing strain, the mutant was found to carry an allele of the wild-type PRO1 gene encoding γ-glutamyl kinase, which resulted in a single amino acid replacement; Asp (GAC) at position 154 was replaced by Asn (AAC). Interestingly, the allele of PRO1 was shown to enhance the activities of γ-glutamyl kinase and γ-glutamyl phosphate reductase, both of which catalyze the first two steps of l-proline synthesis from l-glutamate and which together may form a complex in vivo. When cultured in liquid minimal medium, yeast cells expressing the mutated γ-glutamyl kinase were found to accumulate intracellular l-proline and showed a prominent increase in cell viability after freezing at −20°C compared to the viability of cells harboring the wild-type PRO1 gene. These results suggest that the altered γ-glutamyl kinase results in stabilization of the complex or has an indirect effect on γ-glutamyl phosphate reductase activity...

Gene Dosage Effect of l-Proline Biosynthetic Enzymes on l-Proline Accumulation and Freeze Tolerance in Saccharomyces cerevisiae

Terao, Yukiyasu; Nakamori, Shigeru; Takagi, Hiroshi
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /11/2003 EN
Relevância na Pesquisa
46.6%
We have previously reported that l-proline has cryoprotective activity in Saccharomyces cerevisiae. A freeze-tolerant mutant with l-proline accumulation was recently shown to carry an allele of the PRO1 gene encoding γ-glutamyl kinase, which resulted in a single amino acid substitution (Asp154Asn). Interestingly, this mutation enhanced the activities of γ-glutamyl kinase and γ-glutamyl phosphate reductase, both of which catalyze the first two steps of l-proline synthesis and which together may form a complex in vivo. Here, we found that the Asp154Asn mutant γ-glutamyl kinase was more thermostable than the wild-type enzyme, which suggests that this mutation elevated the apparent activities of two enzymes through a stabilization of the complex. We next examined the gene dosage effect of three l-proline biosynthetic enzymes, including Δ1-pyrroline-5-carboxylate reductase, which converts Δ1-pyrroline-5-carboxylate into l-proline, on l-proline accumulation and freeze tolerance in a non-l-proline-utilizing strain. Overexpression of the wild-type enzymes has no influence on l-proline accumulation, which suggests that the complex is very unstable in nature. However, co-overexpression of the mutant γ-glutamyl kinase and the wild-type γ-glutamyl phosphate reductase was effective for l-proline accumulation...

Senescence of Rice Leaves 1: VII. PROLINE ACCUMULATION IN SENESCING EXCISED LEAVES

Wang, Chang Ying; Cheng, Shu Hua; Kao, Ching Huei
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1982 EN
Relevância na Pesquisa
46.6%
Proline content increased greatly in detached rice (Oryza sativa cv. Taichung Native 1) leaves during senescence. There was a slight but significant increase in proline level after one day of incubation, and, subsequently, proline accumulated relatively rapidly. By 4 days after excision, the level of proline had increased 30- to 50-fold, which is similar to the level seen in the water-stressed detached rice leaves. It is unlikely that the proline accumulation in detached leaves is to be derived solely from protein hydrolysis, since the addition of l-glutamic acid increased the proline level during senescence. The proline analog, 3,4-dehydroproline, did not affect the level of proline during senescence. It seems that accumulation of proline may, at least in part, result from an increased rate of synthesis, possibly due to a disruption of the normal feedback inhibition of proline synthesis. Potassium cyanide and 2,4-dinitrophenol strongly inhibited proline accumulation, indicating that some energy compound(s) may participate in proline accumulation during senescence of excised rice leaves.

Contribution of Arginine to Proline Accumulation in Water-stressed Barley Leaves 1

Boggess, Samuel F.; Stewart, Cecil R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1976 EN
Relevância na Pesquisa
46.48%
Barley (Hordeum vulgare cv Prior) leaves converted l-U-14C-arginine to labeled proline. Accumulation of radioactivity in proline was greater in wilted leaves, but only after 9 hours of incubation. As the increase in free proline was detectable after only 3 to 6 hours, it is likely that the observed stimulation of proline labeling represents a result rather than a cause of proline accumulation. Furthermore, the loss of total arginine during water stress was only 10 to 15% of the increase in proline. We conclude that arginine probably contributes less than 1% of the carbon in the expanding proline pool of wilted barley leaves.

Proline Accumulation in Water-stressed Barley Leaves in Relation to Translocation and the Nitrogen Budget 1

Tully, Raymond E.; Hanson, Andrew D.; Nelsen, Charles E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1979 EN
Relevância na Pesquisa
46.48%
Mobilization of N from leaves of barley (Hordeum vulgare L.) during water stress, and the role of proline as a mobilized species, were examined in plants at the three-leaf stage. The plants responded to water stress by withdrawing about 25% of the total reduced N from the leaf blades via phloem translocation. Most of this N loss was during the first 2 days while translocation of 14C-photosynthate out of the stressed blade still remained active. Free proline accumulation in the blade was initially slow, and became more rapid during the 2nd day of stress. Although a major free amino acid, proline accounted for only about 5% of the total N (soluble + insoluble) retained in severely stressed blades. When the translocation pathway in water-stressed leaves was interrupted just below the blade by a heat girdle, a cold jacket, or by blade excision, N loss from the blade was prevented and proline began to accumulate rapidly on 1st day of stress. Little free proline accumulated in the blades until after the ability to translocate was lost. Proline was, however, probably not a major species of N translocated during stress, because proline N accumulation in heat-girdled stressed leaves was five times slower than the rate of total N export from intact blades.

Ion Fluxes and Abscisic Acid-Induced Proline Accumulation in Barley Leaf Segments

Pesci, Pierantonio
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1988 EN
Relevância na Pesquisa
46.38%
The increase in proline induced by ABA, a process stimulated by NaCl or KCl in barley leaves, did not occur when Na+ (or K+) was present in the external medium as the gluconate salt, namely with an anion unable to permeate the plasma membrane. However, proline increase was restored, to different extents, by the addition of various chloride salts but not by ammonium chloride. Moreover, it was shown that the stimulation of the process by NaCl (or KCl) was variously affected by the presence of different salts; all the ammonium salts (10 millimolar NH4+ concentration) inhibited this stimulation almost completely. Inhibition by NH4+ was accompanied by a decreased Na+ influx (−40%). Also, in the case of Na-gluconate, Na+ uptake was reduced and the addition of Cl− as the calcium or magnesium salt (but not as ammonium salt) restored both the ion influxes and the increase in proline typical of NaCl treatments. Both 4,4′-diisothiocyano-2,2′-disulfonic acid stilbene (DIDS), an anion transport inhibitor, and tetraethylammonium chloride (TEA), a K+ channels-blocking agent, caused, as well as with a reduction of ion influxes, an inhibition of the proline accumulation. The inhibition was practically total with 1 millimolar DIDS and about 80% with 20 millimolar TEA. A possible role of ion influxes in the process leading to the increase in proline induced by ABA is proposed.

The Effects of Benzyladenine, Cycloheximide, and Cordycepin on Wilting-Induced Abscisic Acid and Proline Accumulations and Abscisic Acid- and Salt-Induced Proline Accumulation in Barley Leaves 1

Stewart, Cecil R.; Voetberg, Gary; Rayapati, P. John
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1986 EN
Relevância na Pesquisa
46.7%
Benzyladenine inhibits proline accumulation in wilted, abscisic acid (ABA)-treated, and salt-shocked barley leaves. It does not affect ABA accumulation or disappearance in wilted leaves. Inhibition of proline accumulation in salt-shocked leaves was observed both when benzyladenine was added at the beginning of or after salt treatment. Cycloheximide (CHX) and cordycepin inhibited both ABA and proline accumulations in wilted barley leaves and proline accumulation in ABA-treated leaves. In salt-shocked leaves, cordycepin inhibited proline accumulation when added after salt treatment but before proline began to accumulate but not when added after the onset of proline accumulation. CHX delayed the accumulation of proline in salt-shocked leaves but, after a period of time, proline accumulated in the CHX-treated leaves at rates comparable to the salt-treated control. This delay and subsequent accumulation was observed when CHX was added before, during, and after salt treatment. However, the earlier in the salt treatment period that CHX was given, the longer was the observed delay. These results are interpreted to indicate that gene activation is involved in proline accumulation in response to wilting, to ABA, and to salt in barley leaves. This gene activation is in addition to the gene activation that is required for ABA accumulation in wilted leaves. If ABA accumulation is required for proline accumulation in wilted barley leaves...

Proline Accumulation and Its Implication in Cold Tolerance of Regenerable Maize Callus 1

Duncan, David R.; Widholm, Jack M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1987 EN
Relevância na Pesquisa
46.6%
Embryogenic callus of maize (Zea mays L.) inbreds B37wx, H99, H993H95, Mo17, and Pa91 accumulated proline to levels 2.1 to 2.5 times that of control callus when subjected to mannitol-induced water stress, cool temperatures (19°C) and abscisic acid (ABA). A combination of 0.53 molar mannitol plus 0.1 millimolar ABA induced a proline accumulation to about 4.5 times that of control callus, equivalent to approximately 0.18 millimoles proline per gram fresh weight of callus. Proline accumulation was directly related to the level of mannitol in the medium. Levels of ABA greater than 1.0 micromolar were required in the medium to induce proline accumulation comparable to that induced by mannitol. Mannitol and ABA levels that induced maximum accumulation of proline also inhibited callus growth and increased tolerance to cold. Proline (12 millimolar) added to the culture media also increased the tolerance of callus to 4°C. The increased cold tolerance induced by the combination of mannitol and ABA has permitted the storage of the maize inbreds A632, A634Ht, B37wx, C103DTrf, Fr27rhm, H99, Pa91, Va35, and W117Ht at 4°C for 90 days which is more than double the typical survival time of callus. These studies show that proline and conditions which induce proline accumulation increase the cold tolerance of regenerable maize callus.

Abscisic Acid Accumulation Is Not Required for Proline Accumulation in Wilted Leaves 1

Stewart, Cecil R.; Voetberg, Gary
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1987 EN
Relevância na Pesquisa
46.62%
Leaves from dark-grown barley (Hordeum vulgare L. var Larker) seedlings grown in the presence and absence of fluridone were used to determine whether or not abscisic acid (ABA) accumulation was necessary for proline to accumulate in wilted tissue. Wilted tissue (polyethylene glycol-treated) leaves from fluridone-grown seedlings did not accumulate ABA but did accumulate proline at a rate that was not different from the non-fluridone-treated leaves. Thus ABA accumulation is not required for wilting-induced proline accumulation in barley leaves. Proline accumulation in wilted leaves from the wilty tomato (Lycopersicon esculentum) mutant, flacca, was compared to that in the wild type, Rheinlands Ruhm. Proline accumulated in wilted leaves from flacca. The rate of accumulation was faster in flacca compared to the rate in the wild type because the wilty mutant wilted faster. ABA accumulated in wilted leaves from the wild type but not in the wilty mutant. This result is a further confirmation that ABA accumulation is not required for wilting-induced proline accumulation. These results are significant in that proline accumulation in barley leaves can be induced independently by any one of three treatments: wilting, ABA, or salt.

Characterization of Growth, Water Relations, and Proline Accumulation in Sodium Sulfate Tolerant Callus of Brassica napus L. cv Westar (Canola) 1

Chandler, Stephen F.; Thorpe, Trevor A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1987 EN
Relevância na Pesquisa
46.41%
Unselected and sodium sulfate tolerant callus cultures of Brassica napus L. cv Westar were grown on media supplemented with mannitol, NaCl, or Na2SO4. In all cases, growth of tolerant callus, measured on a fresh weight or dry weight basis, was greater than that of unselected callus, which was also subject to necrosis on high levels of salt. Tissue water potential became more negative in both unselected and tolerant callus grown in the presence of mannitol or Na2SO4. Water potentials in unselected callus were more negative than those of the tolerant tissues; but over a range of Na2SO4 concentrations both cultures displayed osmotic adjustment, maintaining relatively constant turgor. Proline accumulation in both unselected and tolerant callus was low (15 to 20 micromoles per gram dry weight) in the absence of stress, but increased on media supplemented with mannitol, NaCl, or Na2SO4. Increases in proline concentration were approximately linear in tolerant callus, reaching a maximum of 130 to 175 micromoles per gram dry weight. In unselected callus, concentrations were higher, reaching 390 to 520 micromoles per gram dry weight. Proline accumulation was correlated with inhibition of growth, and there was a negative correlation between proline concentration and culture age for tolerant callus.

Proline Accumulation and the Adaptation of Cultured Plant Cells to Water Stress 1

Handa, Sangita; Handa, Avtar K.; Hasegawa, Paul M.; Bressan, Ray A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1986 EN
Relevância na Pesquisa
46.55%
The transfer of cultured tomato cells (Lycopersicon esculentum cv VFNT-Cherry) to a low water potential environment resulted in an increased dry weight to fresh weight ratio accompanied by a rapid accumulation of proline. Proline content continued to increase as osmotic adjustment and growth occurred. The initial increase in proline concentration was accompanied by a drop in turgor. However, proline levels continued to increase with a gain in turgor during osmotic adjustment. Thus, the accumulation of proline depended not only on cell water potential, or on the initial loss of turgor but more closely on cell osmotic potential. The ultimate level of proline depended on the level of adaptation. Proline levels remained high after more than 100 cell generations in low water potential media, but declined rapidly after transfer to media with a less negative water potential. Addition of exogenous proline to the medium during water stress and during osmotic downshock alleviated the normally resulting inhibition of growth. The results suggest a positive role for proline accumulation in adaptation of cells to changing external water potentials.

Role of Carbohydrates in Proline Accumulation in Wilted Barley Leaves 1

Stewart, Cecil R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1978 EN
Relevância na Pesquisa
46.53%
The effect of wilting on proline synthesis, proline oxidation, and protein synthesis—all of which contribute to proline accumulation—was determined in nonstarved barley (Hordeum vulgare L.) leaves. Nonstarved leaves were from plants previously in the light for 24 hours and starved leaves were from plants previously in the dark for 48 hours. Wilted leaves from nonstarved plants accumulated proline at the rate of about 1 μmole per hour per gram of fresh weight whereas wilted leaves from starved plants accumulated very little proline. Wilting caused a 40-fold stimulation of proline synthesis from glutamate in nonstarved leaves but had very little effect in starved leaves. Proline oxidation and protein synthesis, on the other hand, were inhibited by wilting in both nonstarved and starved leaves. Thus, the role of carbohydrates in proline accumulation is to supply precursors for the stimulated proline synthesis. These results further indicate that the main metabolic response causing proline to accumulate in wilted barley leaves is the stimulation of proline synthesis from glutamate. The difference between these results and those obtained with beans is discussed.

Desensitization of Feedback Inhibition of the Saccharomyces cerevisiae γ-Glutamyl Kinase Enhances Proline Accumulation and Freezing Tolerance▿

Sekine, Tomoko; Kawaguchi, Akari; Hamano, Yoshimitsu; Takagi, Hiroshi
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.46%
In response to osmotic stress, proline is accumulated in many bacterial and plant cells as an osmoprotectant. The yeast Saccharomyces cerevisiae induces trehalose or glycerol synthesis but does not increase intracellular proline levels during various stresses. Using a proline-accumulating mutant, we previously found that proline protects yeast cells from damage by freezing, oxidative, or ethanol stress. This mutant was recently shown to carry an allele of PRO1 which encodes the Asp154Asn mutant γ-glutamyl kinase (GK), the first enzyme of the proline biosynthetic pathway. Here, enzymatic analysis of recombinant proteins revealed that the GK activity of S. cerevisiae is subject to feedback inhibition by proline. The Asp154Asn mutant was less sensitive to feedback inhibition than wild-type GK, leading to proline accumulation. To improve the enzymatic properties of GK, PCR random mutagenesis in PRO1 was employed. The mutagenized plasmid library was introduced into an S. cerevisiae non-proline-utilizing strain, and proline-overproducing mutants were selected on minimal medium containing the toxic proline analogue azetidine-2-carboxylic acid. We successfully isolated several mutant GKs that, due to extreme desensitization to inhibition...

Mycorrhizal-Mediated Lower Proline Accumulation in Poncirus trifoliata under Water Deficit Derives from the Integration of Inhibition of Proline Synthesis with Increase of Proline Degradation

Zou, Ying-Ning; Wu, Qiang-Sheng; Huang, Yong-Ming; Ni, Qiu-Dan; He, Xin-Hua
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 18/11/2013 EN
Relevância na Pesquisa
46.61%
Proline accumulation was often correlated with drought tolerance of plants infected by arbuscular mycorrhizal fungi (AMF), whereas lower proline in some AM plants including citrus was also found under drought stress and the relevant mechanisms have not been fully elaborated. In this study proline accumulation and activity of key enzymes relative to proline biosynthesis (▵1-pyrroline-5-carboxylate synthetase, P5CS; ornithine-δ-aminotransferase, OAT) and degradation (proline dehydrogenase, ProDH) were determined in trifoliate orange (Poncirus trifoliata, a widely used citrus rootstock) inoculated with or without Funneliformis mosseae and under well-watered (WW) or water deficit (WD). AMF colonization significantly increased plant height, stem diameter, leaf number, root volume, biomass production of both leaves and roots and leaf relative water content, irrespectively of water status. Water deficit induced more tissue proline accumulation, in company with an increase of P5CS activity, but a decrease of OAT and ProDH activity, no matter whether under AM or no-AM. Compared with no-AM treatment, AM treatment resulted in lower proline concentration and content in leaf, root, and total plant under both WW and WD. The AMF colonization significantly decreased the activity of both P5CS and OAT in leaf...

Proline transport and stress tolerance of ammonia-insensitive mutants of the PUT4-encoded proline-specific permease in yeast

Poole, K.; Walker, M.; Warren, T.; Gardner, J.; McBryde, C.; de Barros Lopes, M.; Jiranek, V.
Fonte: Microbiol Res Foundation Publicador: Microbiol Res Foundation
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
46.45%
The imino amino acid, proline, has roles in both cellular nutrition and response to stress. Proline uptake in Saccharomyces cerevisiae is largely mediated by a high affinity, specific permease, Put4p, and a low affinity general amino acid permease, Gap1p. Both are subject to nitrogen catabolite repression (NCR) and nitrogen catabolite inactivation (NCI). In order for proline to be fully exploited, its transport must be derepressed, as occurs upon depletion of preferred nitrogen sources, and molecular oxygen must be present to allow the first step of catabolism via proline oxidase. This study focuses on the isolation of variants of Put4p, which are insensitive to repression by a preferred nitrogen source (ammonia) and their subsequent effect on proline transport and stress tolerance. Specific amino acid residues in the carboxy-terminal region of Put4p were targeted by site-directed mutagenesis. Substitution at Serine(605), a potential phosphorylation target, led to the amelioration of ammonia-induced down-regulation of Put4p. When combined with a promoter mutation (-160), the S(605)A mutation resulted in increased proline uptake and accumulation. This increase in proline accumulation was associated with increased cell viability in conditions of high temperature and osmotic stress raising possible benefits in industrial fermentation applications.; http://www.ncbi.nlm.nih.gov/pubmed/20118607; Kate Poole...

Acúmulo de prolina em cana-de-açúcar sob estresse hídrico ou submetida ao ataque de cigarrinha-das-raízes; Free proline accumulation in sugarcane under water restriction and spittlebug infestation

Guimarães, Eduardo Rossini; Mutton, Miguel Angelo; Mutton, Márcia Justino Rossini; Ferro, Maria Inês Tiraboschi; Ravaneli, Gisele Cristina; Silva, Jorge Alberto da
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/12/2008 ENG
Relevância na Pesquisa
66.48%
Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) has become a key pest in the sugarcane (Saccharum officinarum) fields of center-south Brazil. Although some control technologies have shown to be efficient, the damage promoted by this spittlebug species and its interaction with sugarcane are poorly characterized. At high infestation levels the symptoms are similar to those of severe water restriction. This work was conducted to determine whether the stress promoted by spittlebug infestation can be measured in terms of free proline accumulation. The water restriction tolerance of two sugarcane genotypes was also compared. Two experiments were set up in a greenhouse and arranged in a completely randomized design in a 2 x 2 x 4 factorial, with two cultivars (SP80-1816 and RB72454), two stress levels (control and ten nymphs per plant or 50% water restriction), and four sampling dates. The water deficit caused by spittlebug nymphs sucking xylem sap does not result in proline accumulation, illustrating that there are different mechanisms to sense when the water deficit is caused by insect feeding or water potential variation in root cells. The cultivar RB72454 accumulates more free-proline, and the dry mass accumulation and stalk growth are less affected in this cultivar under water restriction. The levels of compatible solutes probably cannot be used to measure spittlebug infestation stress in sugarcane and RB72454 is more tolerant to water shortage than SP80-1816.; A cigarrinha-das-raízes Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) tornou-se uma praga importante da cultura da cana-de-açúcar na região centro-sul do Brasil. Estratégias de controle têm sido desenvolvidas...

Biosynthesis of proline in fruits of green bean plants: deficiency versustoxicity of nitrogen

Sánchez,E; Ávila-Quezada,G; Gardea,AA; Ruiz,JM; Romero,L
Fonte: Phyton (Buenos Aires) Publicador: Phyton (Buenos Aires)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 EN
Relevância na Pesquisa
46.42%
The objective of this work was to determine the effect of deficiency versus toxicity of N on biosynthesis of proline in fruits of green bean plants (Phaseolus vulgaris L. cv. Strike). Nitrogen was applied to the nutritive solution in the form of NH4NO3 at 1.5 mM (N1), 3.0 mM (N2), 6.0 mM (N3, optimal level), 12.0 mM (N4), 18.0 mM (N5), and 24.0 mM (N6). Nitrogen deficiency (N1 and N2) was characterized by having lower proline accumulation in pods and seeds, mainly because proline degradation was stimulated by the enzyme proline dehydrogenase. On the other hand, N toxicity (N4, N5, and N6) was characterized for accumulation of greater amounts of proline in pods and seeds due primarily to the greater activity of the enzyme ornitine-δ-aminotransferase. These results suggest a predominance of the ornithine over the glutamine pathway. Under our experimental conditions, proline can be defined as a good bioindicator of N excess in green bean considered a good bioindicator of N toxicity in the study plant species.