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1.
Toxins (Basel) ; 12(2)2020 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-32046323

RESUMO

Sheath rot is an emerging rice disease that leads to considerable yield losses. The main causal agent is the fungus Sarocladium oryzae. This pathogen is known to produce the toxins cerulenin and helvolic acid, but their role in pathogenicity has not been clearly established. S. oryzea isolates from different rice-producing regions can be grouped into three phylogenetic lineages. When grown in vitro, isolates from these lineages differed in growth rate, colour and in the ability to form sectors. A diverse selection of isolates from Rwanda and Nigeria, representing these lineages, were used to further study their pathogenicity and toxin production. Liquid chromatography high-resolution mass spectrometry analysis was used to measure cerulenin and helvolic acid production in vitro and in planta. The three lineages clearly differed in pathogenicity on the japonica cultivar Kitaake. Isolates from the least pathogenic lineage produced the highest levels of cerulenin in vitro. Helvolic acid production was not correlated with the lineage. Sectorisation was observed in isolates from the two least pathogenic lineages and resulted in a loss of helvolic acid production. In planta, only the production of helvolic acid, but not of cerulenin, correlated strongly with disease severity. The most pathogenic isolates all belonged to one lineage. They were phenotypically stable, shown by the lack of sectorisation, and therefore maintained high helvolic acid production in planta.

2.
J Environ Manage ; 254: 109752, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31733478

RESUMO

Awareness about the rising detection and reported (eco)toxicological effects of contaminants of emerging concern (CECs, e.g. pharmaceuticals and personal care products - PPCPs - and modern pesticides) in the aquatic environment is growing. CECs are increasingly reported in the African aquatic environment, although the amount of data available is still limited. In this work, a comprehensive review is presented on the occurrence of CECs in wastewater, sludge, surface water, sediment, groundwater and drinking water of Africa. Further attention is given to the performance of wastewater stabilization ponds (WSPs) and trickling filters (TF) with respect to CECs removal. For the first time, we also look at the state of knowledge on the performance of point-of-use technologies (POUs) regarding the removal of CECs in drinking water. Generally, CECs in Africa occur at the same order of magnitude as in the Western world. However, for particular groups of compounds and at specific locations such as informal settlements, clearly higher concentrations are reported in Africa. Whereas antiretroviral and antimalarial drugs are rarely detected in the Western world, occurrence patterns in Africa reveal concentrations up to >100 µg L-1. Removal efficiencies of WSPs and TFs focus mainly on PPCPs and vary significantly, ranging from no removal (e.g. carbamazepine) to better than 99.9% (e.g. paracetamol). Despite the rising adoption of POUs, limited but promising information is available on their performance regarding CECs treatment in drinking water, particularly for the low-cost devices (e.g. ceramic filters and solar disinfection - SODIS) being adopted in Africa and other developing countries.


Assuntos
Praguicidas , Preparações Farmacêuticas , Poluentes Químicos da Água , África , Monitoramento Ambiental , Águas Residuárias
3.
Front Plant Sci ; 10: 1515, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31824540

RESUMO

Next to their essential roles in plant growth and development, phytohormones play a central role in plant immunity against pathogens. In this study we studied the previously reported antagonism between the plant-pathogenic oomycete Pythium arrhenomanes and the root-knot nematode Meloidogyne graminicola, two root pathogens that co-occur in aerobic rice fields. In this manuscript, we investigated if the antagonism is related to imbalances in plant hormone levels, which could be involved in activation of plant defense. Hormone measurements and gene expression analyses showed that the jasmonate (JA) pathway is induced early upon P. arrhenomanes infection. Exogenous application of methyl-jasmonate (MeJA) on the plant confirmed that JA is needed for basal defense against both P. arrhenomanes and M. graminicola in rice. Whereas M. graminicola suppresses root JA levels to increase host susceptibility, Pythium inoculation boosts JA in a manner that prohibits JA repression by the nematode in double-inoculated plants. Exogenous MeJA supply phenocopied the defense-inducing capacity of Pythium against the root-knot nematode, whereas the antagonism was weakened in JA-insensitive mutants. Transcriptome analysis confirmed upregulation of JA biosynthesis and signaling genes upon P. arrhenomanes infection, and additionally revealed induction of genes involved in biosynthesis of diterpenoid phytoalexins, consistent with strong activation of the gene encoding the JA-inducible transcriptional regulator DITERPENOID PHYTOALEXIN FACTOR. Altogether, the here-reported data indicate an important role for JA-induced defense mechanisms in this antagonistic interaction. Next to that, our results provide evidence for induced expression of genes encoding ERF83, and related PR proteins, as well as auxin depletion in P. arrhenomanes infected rice roots, which potentially further contribute to the reduced nematode susceptibility seen in double-infected plants.

4.
Environ Sci Technol ; 53(18): 10803-10812, 2019 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-31378062

RESUMO

Hydrophilic divinylbenzene (DVB) (Bakerbond) has surfaced as a promising sorbent for active sampling of analytes from aqueous matrices over a very broad polarity range. Given this, hydrophilic DVB may likewise offer potential for passive sampling, if sorbent/water partitioning coefficients (Ksw) were to be available. In this work, static exposure batch experiments were performed to quantitatively study the equilibrium sorption of 131 environmentally relevant organic contaminants (P values ranging from -1.30 to 9.85) on hydrophilic DVB. The superior affinity of hydrophilic DVB, as compared to Oasis HLB, for compounds with a broad polarity range was confirmed by functional Fourier-transform infrared spectroscopy and Raman characterization, demonstrating the presence of carboxyl moieties. Concentration effects were studied by increasing compound concentrations in mixture experiments and resulted in the steroidal endocrine disrupting compounds in higher Ksw, while lower Ksw were obtained for the (alkyl)phenols, personal care products, pesticides, pharmaceuticals, and phthalates. Nevertheless, Ksw remained constant in the said design for equilibrium water concentrations at environmentally relevant seawater levels. An independent analysis of thermodynamic parameters (change in enthalpy, entropy, and Gibbs free energy) revealed the nature of the main partitioning processes. While polar (log P < 4) compounds were mainly served by physisorption, nonpolar (log P > 4) compounds also exhibited binding by multiple hydrogen bonding. In conclusion, this research facilitates the future application of hydrophilic DVB for active as well as passive sampling in the analysis of organic contaminants for monitoring purposes and for toxicity testing.


Assuntos
Praguicidas , Poluentes Químicos da Água , Interações Hidrofóbicas e Hidrofílicas , Compostos de Vinila
5.
Plant Physiol Biochem ; 142: 202-210, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31302409

RESUMO

Activation of induced plant resistance to control pests and diseases is regaining attention in the current climate where chemical pesticides are being progressively banned. Formulations of chitosan oligomers (COS) and pectin-derived oligogalacturonides (OGA), COS-OGA, have previously been described to induce resistance against fungal diseases in different crop plants. Here, we investigated their potential and mode-of-action as preventive measures to control root-knot nematode Meloidogyne graminicola infection in rice. The results show a significant reduction in root-galling and nematode development in rice plants that were treated through foliar application with the COS-OGA formulations FytoSol® and FytoSave® 24 h before nematode inoculation. Hormone measurements, gene expression analyses, corroborated by treatments on salicylic acid (SA) and jasmonic acid (JA)-mutants indicated that the systemic COS-OGA induced defense mechanism against nematodes is not based on SA or JA activation. However, phenylalanine ammonia lyase (PAL) gene expression in roots as well as enzymatic PAL activity in the shoots were significantly induced 24 h after foliar COS-OGA spraying in comparison with untreated plants. COS-OGA-induced systemic defense was abolished in the rice OsPAL4-mutant, demonstrating that COS-OGA-induced defense is dependent on OsPAL4 activation in rice plants.


Assuntos
Antinematódeos/farmacologia , Quitosana/metabolismo , Oryza/parasitologia , Doenças das Plantas/parasitologia , Raízes de Plantas/parasitologia , Tumores de Planta/parasitologia , Tylenchoidea , Animais , Oryza/metabolismo , Fenóis/metabolismo , Doenças das Plantas/prevenção & controle , Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/metabolismo , Propanóis/metabolismo
6.
Mar Pollut Bull ; 142: 350-360, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31232313

RESUMO

Knowledge about the occurrence of emerging organic micropollutants in the marine environment is still very limited, especially when focusing on the Belgian Part of the North Sea (BPNS). This study therefore optimized and validated a Speedisk® based SPE and LC-Q-Orbitrap HRMS method to tackle the challenge of measuring the expected ultra-trace concentrations in seawater. This method was applied to 18 samples collected at different locations in the open sea and harbor of the BPNS. Forty-eight compounds, among which several pharmaceuticals, personal care products or pesticides described in the EU Watchlist, were detected - some for the first time in seawater - at concentrations ranging up to 156 ng L-1. Moreover, the untargeted screening potential of the newly developed HRMS method was highlighted by revealing the presence of up to 1300 unknown components in a single sample and by assigning molecular formulae to those components demonstrating high discriminative potential between samples.


Assuntos
Monitoramento Ambiental/métodos , Espectrometria de Massas/métodos , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Bélgica , Cromatografia Líquida de Alta Pressão/métodos , Cosméticos/análise , Mar do Norte , Praguicidas/análise , Preparações Farmacêuticas/análise , Reprodutibilidade dos Testes , Água do Mar/química
7.
Environ Toxicol Chem ; 38(6): 1313-1322, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30924961

RESUMO

To estimate mixture effects caused by the high number of chemicals simultaneously present in the environment, methods for routine effect assessment of environmentally realistic contaminant mixtures are needed. We repeatedly exposed the marine diatom Phaeodactylum tricornutum to SpeediskTM passive sampler extracts and observed statistically significant growth stimulation up to 6 and 7% for samples from inside and outside the harbor of Zeebrugge, respectively. These effects were found at summed contaminant concentrations (159-166 ng L-1 ) that were within a 1.1- to 2.4-fold range of those observed in grab water samples taken during sampler deployment. These stimulatory effects were confirmed in 2 independent tests with extracts stored for <1 or 8 mo that had undergone limited sample handling, whereas no effects were observed for extracts that had been stored for 16 mo that had undergone repeated handling (notably repeated freezing and thawing) before biotest spiking. Targeted analysis by ultra-high performance liquid chromatography was performed to quantify 88 personal care products (n = 8), pesticides (n = 28), and pharmaceuticals (n = 52). Among these compounds, multivariate statistical analysis put forward the ß-blocker atenolol as explaining most of the observed variation in mixture composition between the growth-stimulating and no effect-causing extracts. However, when tested individually over the entire concentration range present in the extracts, atenolol did not have any effect on P. tricornutum, suggesting that nontargeted substances in the extracts may have contributed to the observed stimulatory effects. Nevertheless, the present study shows that exposure to contaminant mixtures at environmentally realistic concentrations can lead to small but significant growth stimulation effects on the marine diatom P. tricornutum. Environ Toxicol Chem 2019;38:1313-1322. © 2019 SETAC.

8.
Environ Sci Pollut Res Int ; 26(9): 9065-9078, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30715706

RESUMO

An analytical method was developed for the trace quantification of oxygenated polycyclic aromatic hydrocarbons (oxyPAHs) in mussels. Compounds included were naphthalene-1-ol, 9H-fluoren-9-one, anthracene-9,10-dione, 7H-benz[de]anthracene-7-one, naphtacene-5,12-dione, and benzo[a]anthracene-7,12-dione. Pyrene-1-carboxaldehyde was applied as an internal standard. Sample extraction by pressurized liquid extraction was followed by cleanup on silica, separation by high performance liquid chromatography, and quantitative measurement by mass spectrometry with atmospheric pressure chemical ionization. The method was validated by the analysis of spiked mussel samples, resulting in trueness values of 90-124% and measurement uncertainties of 6-49%, except for naphthalene-1-ol. Quantification limits varied from 0.25 ng·g-1 to 10.7 ng·g-1. The developed analytical oxyPAH method was applied on mussel samples from groynes and quaysides along the Belgian coastline and oxyPAH data were compared to PAH concentration data. The sum of 14 US EPA priority PAHs reached maxima at the eastern side of the Belgian coastal zone, with on average 202 ng·g-1 wet weight for quayside Zeebrugge and 38.4 ng·g-1 wet weight for groyne Knokke mussels. Anthracene-9,10-dione concentrations reached maxima of 19.1 ng·g-1 wet weight at the most industrialized quayside of Zeebrugge. For other oxyPAHs, no clear relationship could be made with direct PAH emissions. Concentrations of anthracene-9,10-dione and 9H-fluoren-9-one were found to exceed corresponding parent PAH concentrations.


Assuntos
Bivalves/química , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Espectrometria de Massas/métodos , Hidrocarbonetos Policíclicos Aromáticos/análise , Frutos do Mar/análise , Animais , Bélgica , Oxigênio/química
9.
Anal Chim Acta ; 1049: 141-151, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30612645

RESUMO

Plasticizers and other plastics additives have been extensively used as ingredients of plastics and are as a result thereof easily released in the aquatic environment, due to different physical diffusion processes. In this context, a dedicated method was developed for the simultaneous quantification of 27 known and a virtually unlimited number of unknown alkylphenols, Bisphenol A and phthalates in 2 aquatic matrices, i.e. sea- and freshwater. To this extent, a novel instrumental HESI-UHPLC-HRMS (heated electro-spray ionization ultra-high performance liquid chromatographic high resolution mass spectrometric) method was devised for the simultaneous analysis of 7 phenols (i.e. 6 alkylphenols and Bisphenol A) and 20 phthalates within 10 min. Thereafter, a solid-phase extraction protocol was statistically (95% confidence interval, p > 0.05) optimized based on experimental designs. The method was proven fit-for-purpose through a successful validation at environmentally relevant nanomolar concentrations. Analytical precautions were taken for minimizing false-positive results to suppress in-house contamination. The method demonstrated an excellent analytical performance across all known plasticizers and plastics additives for sea- and freshwater, revealing good linearity (R2 > 0.99, n = 39), stable recoveries (98.5-105.8%), satisfactory repeatability (RSD < 8%, n = 54) and reproducibility (RSD < 10%, n = 36). Subsequently, a novel analytical strategy was devised for the tentative identification of unknown plasticizers and plastics additives using specific in-house determined fragments incorporated in a Python code. The applicability of the analytical platform was demonstrated by measuring 24 seawater samples. Interestingly, 16 out of 27 known plasticizers, plastics additives and primary metabolites could be quantified while the untargeted analysis uncovered 1042 compounds, whereof 5% (n = 46) could be assigned a plasticizer-plastics additive chemical identity, providing evidence for the severe plastic contamination status of our marine environment.

10.
J Hazard Mater ; 360: 204-213, 2018 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-30099363

RESUMO

Given the need for innovations in advanced oxidation processes to deal with challenges such as OH scavenging, this paper addresses the removal of pharmaceuticals with a large variety in ozone reactivity (kO3 = 0.15-3 × 105 M-1s-1) by use of the novel ozone-activated peroxymonosulfate (O3/PMS) process. A clear improvement in removal efficiency (up to 5 times higher) is noticed as a result of the generation of SO4- radicals, mainly for slow-ozone reacting compounds (kO3 ≤ 250 M-1s-1) and in the presence of a OH scavenger. Depending on the target compound, SO4- are assessed to contribute for 50-90% to the overall removal of the micropollutants, both in single-compound and mixture experiments. Ozone-based PMS activation occurs at neutral to alkaline pH and, in the presence of a OH scavenger, removal efficiencies during O3/PMS are up to 3 times higher than with the O3/H2O2 process. In optimizing the O3/PMS process, a trade-off has to made between the desired removal and the PMS:O3 ratio. A molar ratio of 1:10 already results in a clear benefit compared to the ozonation process. Further increase of the PMS content up to a 1:1 ratio improved the removal by an additional factor of 1.3-1.5.


Assuntos
Peróxidos/química , Preparações Farmacêuticas/química , Poluentes Químicos da Água/química , Atrazina/química , Clorobenzoatos/química , Oxirredução , Ozônio/química , Purificação da Água/métodos
11.
Sci Total Environ ; 625: 1198-1207, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29996416

RESUMO

Ozonation is known for removing trace organic contaminants (TrOCs) from secondary wastewater effluent. However, its implementation and overall efficiency on a broad scale depends on effluent characteristics, which can differ both in time as well as between different treatment plants (nowadays referred to as water resource recovery facilities (WRRFs)). Therefore, water quality was assessed over time at 15 different Belgian sampling locations to increase the understanding of effluent variability in view of online control of the tertiary ozonation step. Conventional and surrogate parameters as well as those specifically related to tertiary ozonation (e.g. instantaneous ozone demand) were assessed. Little differences between the different locations were found for spectral measurements (e.g. UVA254 or fluorescence). The small amount of observed outliers was clearly site or event dependent. A lower variability (for spectral measurements) is advantageous in simplifying the development and application of a generic control framework based on these spectral measurements. In addition, also variations in TrOC concentration levels seemed to be small, as the concentration of most individual compounds resided within one order of magnitude over multiple sampling events at two different WRRFs. The combination of this low variability in TrOC levels in the effluent before ozonation with a control strategy using a TrOC removal efficiency set-point, allows to indicatively assess absolute TrOC levels after ozonation. In contrast, significant variations between different plants (especially smaller sized plants) were observed and could be related to the conventional water quality parameters alkalinity (correlated with the electrical conductivity) and pH which are both known to have an influence on the ozonation process. This confirms that a differential dosing control strategy (i.e. accounting for the matrix reactivity) should be applied instead of one solely based on the (organic) effluent load before ozonation.

12.
Anal Bioanal Chem ; 410(18): 4527-4539, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29796899

RESUMO

Phytohormones are signaling and regulating metabolites involved in numerous plant processes, including growth, development, and responses to stress. Currently, the focus is on the analysis of multiple phytohormones in order to characterize crosstalk and hormone signaling networks. In this paper, representative phytohormones of the major classes are simultaneously determined in rice tissues by a generic solid-liquid extraction, followed by liquid chromatography and electrospray ionization high-resolution tandem mass spectrometry using a Q-Exactive™ instrument. After a thorough optimization of the sample preparation, the analytical method was fully validated toward the ultra-trace quantification of six a priori selected plant hormones using three scan modes of the quadrupole-Orbitrap instrument: full-scan high-resolution mass spectrometry, targeted single ion monitoring (t-SIM), and t-SIM followed by data-dependent tandem mass spectrometry. Overall, a similar quantitative performance was noticed for the different scan modes. The analytical method was successfully applied to measure basal phytohormone levels in six different rice accessions, comprising Oryza sativa ssp. japonica, indica, and Oryza glaberrima. Hormone concentrations were higher in shoots than in roots or at least similar. Except for a lower level of salicylic acid in shoots of O. glaberrima versus O. sativa, no other differences in hormone levels could be noticed that were dependent of the (sub)species assignment of the analyzed accessions. Making use of the benefits of full-scan high-resolution mass spectrometry, a first post-run suspect screening was performed, suggesting - based on accurate mass measurements and isotopic patterns - the possible presence of about 50 additional plant hormones in the rice tissues. Graphical abstract ᅟ.


Assuntos
Oryza/química , Reguladores de Crescimento de Planta/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida/métodos , Limite de Detecção , Oryza/classificação , Reguladores de Crescimento de Planta/isolamento & purificação , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , Extração em Fase Sólida/métodos , Especificidade da Espécie
13.
Sci Total Environ ; 637-638: 336-348, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29751313

RESUMO

Although there is increased global environmental concern about emerging organic micropollutants (EOMPs) such as pharmaceuticals, personal care products (PPCPs) and polar pesticides, limited information is available on their occurrence in Africa. This study presents unique data on concentrations and loads of 31 PPCPs and 10 pesticides in four wastewater stabilization ponds (WSPs) and receiving rivers (flowing through urban centres) in Kenya. The WSPs indicate a high potential to remove pharmaceutically active compounds (PhACs) with removals by up to >4 orders of magnitude (>99.99% removal), mainly occurring at the facultative stage. However, there are large differences in removal among the different classes, and a shift in the relative PhACs occurrence is observed during wastewater treatment. Whereas the influent is dominated by high-consumption PhACs like anti-inflammatory drugs (e.g. paracetamol and ibuprofen, up to 1000 µg L-1), the most recalcitrant PhACs including mainly antibiotics (e.g. sulfadoxin and sulfamethoxazole) and antiretrovirals (e.g. lamivudine and nevirapine) are largely abundant (up to 100 µg L-1) in treated effluent. Overall, concentrations of EOMPs in the Nzoia Basin rivers are the highest in dry season (except pesticides) and in small tributaries. They are of the same order of magnitude as those measured in the western world, but clearly lower than what we recently measured in the Ngong River, Nairobi region. Based on the specific consumption patterns and recalcitrant behavior, high concentrations (>1000 ng L-1) are observed in the rivers for PPCPs like lamivudine, zidovudine, sulfamethoxazole and methylparaben. Concentration levels of pesticides are in general one order of magnitude lower (<250 ng L-1). Our data suggest a continuous input of EOMPs to the rivers from both point (WSPs) and diffuse (urban centres) sources. To better understand and manage the impact of both sources, EOMP removal mechanisms in WSPs and their attenuation in rivers merit further research.


Assuntos
Cosméticos/análise , Monitoramento Ambiental , Praguicidas/análise , Preparações Farmacêuticas/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Quênia , Tanques , Rios , Águas Residuárias/química , Águas Residuárias/estatística & dados numéricos
14.
Sci Rep ; 8(1): 3864, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29497084

RESUMO

Sucrose non-fermenting-1-related protein kinase-1 (SnRK1) belongs to a family of evolutionary conserved kinases with orthologs in all eukaryotes, ranging from yeasts (SnF1) to mammals (AMP-Activated kinase). These kinases sense energy deficits caused by nutrient limitation or stress and coordinate the required adaptations to maintain energy homeostasis and survival. In plants, SnRK1 is a global regulator of plant metabolism and is also involved in abiotic stress responses. Its role in the response to biotic stress, however, is only starting to be uncovered. Here we studied the effect of altered SnRK1a expression on growth and plant defense in rice. OsSnRK1a overexpression interfered with normal growth and development and increased resistance against both (hemi)biotrophic and necrotrophic pathogens, while OsSnRK1a silencing in RNAi lines increased susceptibility. OsSnRK1a overexpression positively affected the salicylic acid pathway and boosted the jasmonate-mediated defense response after inoculation with the blast fungus Pyricularia oryzae. Together these findings strongly suggest OsSnRK1a to be involved in plant basal immunity and favor a model whereby OsSnRK1a acts as a master switch that regulates growth-immunity trade-offs.


Assuntos
Oryza/imunologia , Doenças das Plantas/imunologia , Proteínas de Plantas/imunologia , Proteínas Serina-Treonina Quinases/imunologia , Adaptação Fisiológica/genética , Adaptação Fisiológica/imunologia , Ciclopentanos/metabolismo , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Oryza/genética , Oryza/metabolismo , Oxilipinas/metabolismo , Imunidade Vegetal , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Ácido Salicílico/metabolismo
15.
New Phytol ; 218(2): 646-660, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29464725

RESUMO

Gibberellin (GA) regulates various plant growth and developmental processes, but its role in pathogen attack, and especially nematode-plant interactions, still remains to be elucidated. An in-depth characterization of the role of GA in nematode infection was conducted using mutant lines of rice, chemical inhibitors, and phytohormone measurements. Our results showed that GA influences rice-Meloidogyne graminicola interactions in a concentration-dependent manner. Foliar spray of plants with a low concentration of gibberellic acid enhanced nematode infection. Biosynthetic and signaling mutants confirmed the importance of gibberellin for rice susceptibility to M. graminicola infection. Our study also demonstrates that GA signaling suppresses jasmonate (JA)-mediated defense against M. graminicola, and likewise the JA-induced defense against M. graminicola requires SLENDER RICE1 (SLR1)-mediated repression of the GA pathway. In contrast to observations from other plant-pathogen interactions, GA plays a dominant role over JA in determining susceptibility to M. graminicola in rice. This GA-induced nematode susceptibility was largely independent of auxin biosynthesis, but relied on auxin transport. In conclusion, we showed that GA-JA antagonistic crosstalk is at the forefront of the interaction between rice and M. graminicola, and SLR1 plays a central role in the JA-mediated defense response in rice against this nematode.


Assuntos
Ciclopentanos/farmacologia , Giberelinas/farmacologia , Oryza/imunologia , Oryza/parasitologia , Oxilipinas/farmacologia , Tylenchoidea/fisiologia , Animais , Transporte Biológico/efeitos dos fármacos , Suscetibilidade a Doenças , Ácidos Indolacéticos/metabolismo , Modelos Biológicos , Oryza/efeitos dos fármacos , Doenças das Plantas/imunologia , Doenças das Plantas/parasitologia , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Tumores de Planta/parasitologia , Tylenchoidea/efeitos dos fármacos
16.
Chemosphere ; 196: 494-501, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29324389

RESUMO

New robust correlation models for ozonation, based on UVA254 and fluorescence surrogate parameters and developed considering kinetic information, have been applied at pilot-scale. This model framework is validated with the aim for operators to control the ozone dose for the removal of trace organic contaminants (TrOCs) in effluents from full-scale municipal wastewater treatment plants. The inflected correlation model between ΔTrOCs and the surrogates predicts the removal of TrOCs (based on statistical evidence) solely using the 2nd order reaction rate constant with ozone (kO3) and in a more adequate manner than similar single correlation models. This allows the use of this new model for current and future TrOCs under investigation which is highly interesting when imposed discharge limits might include more and other TrOCs in future. The use of UVA254 might be preferable at the current timing for online monitoring of TrOC abatement as the model showed a good predictive power (based on statistical evidence and visual confirmation). Reliable online sensors are more widespread (and commercially) available compared to fluorescence sensors which are still under development, with the exception of a few examples. Nevertheless, the data processing of the fluorescence signals, isolating the different intensities associated with moieties reacting similarly to ozone might even increase the predictive power, given the lower degree of interference (i.e. less scattering).


Assuntos
Ozônio/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Cinética , Projetos Piloto , Águas Residuárias/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise
17.
Mol Plant Pathol ; 19(6): 1391-1402, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-28990717

RESUMO

The incompatible interaction between the rice cultivar Manikpukha and the rice stem nematode Ditylenchus angustus has been reported recently. This research focuses on the underlying mechanisms of resistance in Manikpukha. Invasion, post-infection development and reproduction of D. angustus were compared in compatible and incompatible interactions to identify the stage in which resistance occurs. The results indicate that resistance in Manikpukha is associated with reduced development and reproduction, implying that resistance acts post-invasion. We studied the possible involvement of three classical defence hormones, salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), in response to infection in a compatible interaction using biosynthesis/signalling-deficient transgenic rice lines. All three hormones appear to have an influence on the basal defence of Nipponbare against the stem nematode. Although hormone application increases basal defences, expression studies and hormone analyses after nematode infection in Manikpukha did not show a clear involvement of the hormone defense pathways for SA, ET and JA. However, it seems that OsPAL1 plays a pivotal role in resistance, indicating that the phenylpropanoid pathway and its products might be key players in the incompatible interaction. Lignin measurement showed that, although basal levels are similar, Manikpukha had a significantly higher lignin content on nematode infection, whereas it was decreased in the susceptible cultivar. The results presented here show that SA, ET and JA are involved in basal defences, but the resistance of Manikpukha against D. angustus probably relies on products of the phenylpropanoid pathway.


Assuntos
Oryza/parasitologia , Doenças das Plantas/parasitologia , Tylenchoidea/patogenicidade , Animais , Regulação da Expressão Gênica de Plantas , Lignina/metabolismo , Oryza/genética , Oryza/metabolismo
18.
New Phytol ; 217(1): 305-319, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28905991

RESUMO

Plant defense to microbial pathogens is often accompanied by significant growth inhibition. How plants merge immune system function with normal growth and development is still poorly understood. Here, we investigated the role of target of rapamycin (TOR), an evolutionary conserved serine/threonine kinase, in the plant defense response. We used rice as a model system and applied a combination of chemical, genetic, genomic and cell-based analyses. We demonstrate that ectopic expression of TOR and Raptor (regulatory-associated protein of mTOR), a protein previously demonstrated to interact with TOR in Arabidopsis, positively regulates growth and development in rice. Transcriptome analysis of rice cells treated with the TOR-specific inhibitor rapamycin revealed that TOR not only dictates transcriptional reprogramming of extensive gene sets involved in central and secondary metabolism, cell cycle and transcription, but also suppresses many defense-related genes. TOR overexpression lines displayed increased susceptibility to both bacterial and fungal pathogens, whereas plants with reduced TOR signaling displayed enhanced resistance. Finally, we found that TOR antagonizes the action of the classic defense hormones salicylic acid and jasmonic acid. Together, these results indicate that TOR acts as a molecular switch for the activation of cell proliferation and plant growth at the expense of cellular immunity.


Assuntos
Oryza/fisiologia , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologia , Proliferação de Células/efeitos dos fármacos , Ciclopentanos/metabolismo , Oryza/efeitos dos fármacos , Oryza/genética , Oryza/crescimento & desenvolvimento , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo
19.
Environ Sci Technol ; 51(24): 14233-14243, 2017 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-29172510

RESUMO

New robust correlation models for real-time monitoring and control of trace organic contaminant (TrOC) removal by ozonation are presented, based on UVA254 and fluorescence surrogates, and developed considering kinetic information. The abatement patterns of TrOCs had inflected shapes, controlled by the reactivity of TrOCs toward ozone and HO• radicals. These novel and generic correlation models will be of importance for WRRF operators to reduce operational costs and minimize byproduct formation. Both UVA254 and fluorescence surrogates could be used to control ΔTrOC, although fluorescence measurements indicated a slightly better reproducibility and an enlarged control range. The generic framework was validated for several WRRFs and correlations for any compound with known kinetic information could be developed solely using the second order reaction rate constant with ozone (kO3). Two distinct reaction phases were defined for which separate linear correlations were obtained. The first was mainly ozone controlled, while the second phase was more related to HO• reactions. Furthermore, parallel factor analysis of the fluorescence spectra enabled monitoring of multiple types of organic matter with different O3 and HO• reactivity. This knowledge is of value for kinetic modeling frameworks and for achieving a better understanding of the occurring changes of organic matter during ozonation.


Assuntos
Ozônio , Eliminação de Resíduos Líquidos , Purificação da Água , Reprodutibilidade dos Testes , Águas Residuárias , Poluentes Químicos da Água
20.
Anal Chim Acta ; 984: 140-150, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28843557

RESUMO

The lack of adequate strategies for monitoring endocrine disrupting compounds (EDCs) in the aquatic environment is emphasized in the European Water Framework Directive. In this context, a new UHPLC-HR-Q-Orbirtrap-MS multi-residue method was developed for the simultaneous measurement of 70 steroidal EDCs in two aquatic matrices, i.e. sea and fresh water. First, an instrumental APCI-UHPLC-HR-Q-Orbitrap-MS was devised for separating and detecting the EDC isomers and mass analogues, within 12.5 min per run. Next, an appropriate extraction was statistically optimised using a three-strep workflow (95% confidence interval, p > 0.05); including fractional factorial resolution IV, simplex lattice, and response surface methodological designs. The fitness-for-purpose of the method was demonstrated through successful validation at relevant environmental concentrations, i.e. the low nano- and picogram range. Method quantification limits ranged for the androgens (n = 33), oestrogens (n = 14), progestins (n = 12), and corticosteroids (n = 11) between, respectively, 0.13 and 5.00 ng L-1, 0.25 and 5.00 ng L-1, 0.13 and 2.50 ng L-1, and 0.50 and 5.00 ng L-1. Good linearity (R2 ≥ 0.99) and no lack of fit was observed (95% confidence interval, p > 0.05) for the 70 steroidal EDCs. In addition, good recovery (95-109%) and satisfactory repeatability (RSD < 8.5%, n = 18) and reproducibility (RSD < 10.5%, n = 12) were obtained. Finally, the applicability of the multi-residue method was demonstrated by measuring steroidal EDC in 28 sea water samples collected from four different locations during fall 2016 and winter 2017. Regarding the sea water samples, all the classes were ubiquitously present and included different metabolites, transformation product and or degradation products from the parent EDCs (n = 43).


Assuntos
Cromatografia Líquida de Alta Pressão , Disruptores Endócrinos/análise , Monitoramento Ambiental , Espectrometria de Massas , Poluentes Químicos da Água/análise , Reprodutibilidade dos Testes
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