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1.
J Agric Food Chem ; 67(45): 12382-12392, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31635461

RESUMO

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4) is a promising target for herbicide discovery. Search for new compounds with novel chemotypes is a key objective for agrochemists. Here, we describe the discovery and systematic SAR-based structure optimization of novel N-isoxazolinylphenyltriazinones 5-9 as PPO inhibitors. The in vivo herbicidal activity and in vitro Nicotiana tabacum PPO (NtPPO) inhibitory activity were explored in detail. A number of the new synthetic compounds displayed strong PPO inhibitory activity with Ki values in the nanomolar range. Some compounds exhibited excellent and broad-spectrum weed control at the rate of 9.375-37.5 g ai/ha by postemergence application and showed improved monocotyledonous weed control compared to saflufenacil. Most promisingly, ethyl 3-(2-chloro-5-(3,5-dimethyl-2,6-dioxo-4-thioxo-1,3,5-triazinan-1-yl)-4-fluorophenyl)-5-methyl-4,5-dihydroisoxazole-5-carboxylate, 5a, with a Ki value of 4.9 nM, displayed over 2- and 6-fold higher potency than saflufenacil (Ki = 10 nM) and trifludimoxazin (Ki = 31 nM), respectively. Moreover, 5a showed excellent and broad-spectrum weed control against 32 kinds of weeds at 37.5-75 g ai/ha. Rice exhibited relative tolerance to 5a at 150 g ai/ha by postemergence application, indicating that 5a could be a potential herbicide candidate for weed control in paddy fields.


Assuntos
Inibidores Enzimáticos/farmacologia , Herbicidas/química , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Protoporfirinogênio Oxidase/antagonistas & inibidores , Descoberta de Drogas , Inibidores Enzimáticos/química , Cinética , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Daninhas/química , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/enzimologia , Protoporfirinogênio Oxidase/química , Protoporfirinogênio Oxidase/metabolismo , Relação Quantitativa Estrutura-Atividade , Tabaco/química , Tabaco/efeitos dos fármacos , Tabaco/enzimologia , Controle de Plantas Daninhas
2.
DNA Cell Biol ; 38(11): 1278-1291, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31584843

RESUMO

The plants being sessile cannot escape from the adverse environmental stresses, hence get negatively affected in terms of their growth and yield. Transcriptional control simultaneously regulate different cellular processes, minimizing the deleterious effects of these stresses. The salicylic acid (SA)-inducible WRKY family of transcription factors auto or crossregulate the stress signaling in response to abiotic and biotic stresses, facilitating enhanced stress tolerance. In this study, we characterized the group III WRKY gene, JcWRKY2 from ecological and economical valued shrub Jatropha curcas. The JcWRKY2 tobacco transgenics showed improved physiological growth parameters, elevated chlorophyll content, improved antioxidative activities, and increased endogenous SA with both salt and SA stress. Interestingly, the pretreatment with SA and hydrogen peroxide facilitated improved germination of transgenic seeds with salinity stress. The transgenics showed differential regulation of antioxidative enzymes, calcium/calmodulin, dehydrins, and phospholipase genes with salt and SA stress. The increased SA content in transgenics on stress treatments, enhanced the antioxidant capacity leading to reduced susceptibility to stresses. Thus, JcWRKY2 transgenics participate in SA-mediated, improved antioxidative status during salinity stress with reduced reactive oxygen species damage.


Assuntos
Jatropha/genética , Estresse Salino/genética , Tolerância ao Sal/genética , Tabaco/genética , Fatores de Transcrição/fisiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Germinação/efeitos dos fármacos , Germinação/genética , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Plantas Geneticamente Modificadas , Salinidade , Cloreto de Sódio/farmacologia , Estresse Fisiológico/genética , Tabaco/efeitos dos fármacos , Tabaco/crescimento & desenvolvimento , Fatores de Transcrição/genética
3.
Ecotoxicol Environ Saf ; 183: 109516, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31394375

RESUMO

The triclosan (TCS) is one of the most commonly detected organic pollutants in the sewage sludge. TCS could induce phytotoxicity in plants. Salicylic acid (SA) is a phenolic compound capable of enhancing plant growth and development. It is well documented that abiotic stress tolerance could be enhanced by exogenous application of SA. However, the regulatory mechanisms for functions of endogenous SA in plants' responses to xenobiotics stress remains unclear. Our results indicated that TCS suppressed plant growth by restricting photosynthesis, decreasing chlorophyll contents and inducing over production of reactive oxygen species (ROS). Interestingly, SA or glutathione (GSH) application could significantly improve plant tolerance to TCS. Moreover, endogenous SA and the expression of a SA binding protein 2 (SABP2) gene were found to be elevated in tobacco under TCS treatment. The overexpression of LcSABP, a SABP2-like gene cloned from the leaves of Lycium chinense, markedly enhanced the SA content in the transgenic plants under TCS stress. The LcSABP-overexpressing plants presented higher photosynthesis rate, chlorophyll content, glutathione reductase (GR) and glutathione-S-transferase (GST) enzymes activities, GSH content and lower O2-•, H2O2 and malondialdehyde (MDA) content in comparison with WT tobacco with TCS treatment. One of the GSH synthesis-related gene, NtGSHS, also showed higher expression level in the transgenic tobacco in comparison with control plants with TCS stress treatment. These results indicated that SABP2 played a positive regulatory role in plant response to TCS stress via increasing the endogenous SA levels. The increased SA content might then increase the GSH content, probably through an increase in GR activity and GSHS gene expression, thus inducing the antioxidant and xenobiotics detoxification systems, which promoted TCS stress tolerance in tobacco plants.


Assuntos
Esterases/genética , Lycium/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/metabolismo , Estresse Fisiológico/genética , Tabaco/metabolismo , Triclosan/toxicidade , Antioxidantes/metabolismo , Clorofila/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Fotossíntese/genética , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Espécies Reativas de Oxigênio/metabolismo , Ácido Salicílico/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Tabaco/efeitos dos fármacos , Tabaco/genética
4.
Int J Mol Sci ; 20(15)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374993

RESUMO

Cadmium (Cd) is an environmental pollutant that potentially threatens human health worldwide. Developing approaches for efficiently treating environmental Cd is a priority. Selenium (Se) plays important role in the protection of plants against various abiotic stresses, including heavy metals. Previous research has shown that Se can alleviate Cd toxicity, but the molecular mechanism is still not clear. In this study, we explore the function of auxin and phosphate (P) in tobacco (Nicotiana tabacum), with particular focus on their interaction with Se and Cd. Under Cd stress conditions, low Se (10 µM) significantly increased the biomass and antioxidant capacity of tobacco plants and reduced uptake of Cd. We also measured the auxin concentration and expression of auxin-relative genes in tobacco and found that plants treated with low Se (10 µM) had higher auxin concentrations at different Cd supply levels (0 µM, 20 µM, 50 µM) compared with no Se treatment, probably due to increased expression of auxin synthesis genes and auxin efflux carriers. Overexpression of a high affinity phosphate transporter NtPT2 enhanced the tolerance of tobacco to Cd stress, possibly by increasing the total P and Se content and decreasing Cd accumulation compared to that in the wild type (WT). Our results show that there is an interactive mechanism among P, Se, Cd, and auxin that affects plant growth and may provide a new approach for relieving Cd toxicity in plants.


Assuntos
Cádmio/toxicidade , Poluentes Ambientais/toxicidade , Ácidos Indolacéticos/metabolismo , Selênio/metabolismo , Tabaco/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteínas de Transporte de Fosfato/genética , Proteínas de Transporte de Fosfato/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/genética , Tabaco/crescimento & desenvolvimento
5.
J Plant Physiol ; 240: 153011, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31357099

RESUMO

Phytochelatin synthase (PCS) is an enzyme that synthesizes phytochelatins, which are metal-binding peptides. Despite the important role of PCS in heavy metal detoxification or tolerance, the functional role of PCS with respect to other abiotic stresses remains largely unknown. In this study, we determined the function of Arabidopsis thaliana phytochelatin synthase 2 (AtPCS2) in the salt stress response. Expression of AtPCS2 was significantly increased in response to 100 and 200 mM NaCl treatment. AtPCS2-overexpressing transgenic Arabidopsis and tobacco plants displayed increased seed germination rates and seedling growth under high salt stress. In addition, transgenic Arabidopsis subjected to salt stress exhibited enhanced proline accumulation and reduced Na+/K+ ratios compared to wild type plants. Furthermore, decreased levels of hydrogen peroxide (H2O2) and lipid peroxidation were observed in transgenic Arabidopsis compared to wild type specimens. Salt stress greatly reduced transcript levels of CuSOD2, FeSOD2, CAT2, and GR2 in wild type but not transgenic Arabidopsis. Notably, levels of CAT3 in transgenic Arabidopsis were markedly increased upon salt stress, suggesting that low accumulation of H2O2 in transgenic Arabidopsis is partially achieved through induction of CAT. Collectively, these results suggest that AtPCS2 plays a positive role in seed germination and seedling growth under salt stress through a series of indirect effects that are likely involved in H2O2 scavenging, regulation of osmotic adjustment and ion homeostasis.


Assuntos
Aminoaciltransferases/genética , Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/fisiologia , Tolerância ao Sal/genética , Cloreto de Sódio/farmacologia , Tabaco/fisiologia , Aminoaciltransferases/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Relação Dose-Resposta a Droga , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/enzimologia , Plantas Geneticamente Modificadas/genética , Tabaco/efeitos dos fármacos , Tabaco/enzimologia , Tabaco/genética
6.
J Agric Food Chem ; 67(33): 9254-9264, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31356740

RESUMO

In continuation of our search for potent protoporphyrinogen IX oxidase (PPO, EC 1.3.3.4) inhibitors, we designed and synthesized a series of novel herbicidal cycloalka[d]quinazoline-2,4-dione-benzoxazinones. The bioassay results of these synthesized compounds indicated that most of the compounds exhibited very strong Nicotiana tabacum PPO (NtPPO) inhibition activity. More than half of the 37 synthesized compounds displayed over 80% control of all three tested broadleaf weeds at 37.5-150 g ai/ha by postemergent application, and a majority of them showed no phytotoxicity toward at least one kind of crop at 150 g ai/ha. Promisingly, 17i (Ki = 6.7 nM) was 6 and 4 times more potent than flumioxazin (Ki = 46 nM) and trifludimoxazin (Ki = 31 nM), respectively. Moreover, 17i displayed excellent, broad-spectrum herbicidal activity, even at levels as low as 37.5 g ai/ha, and it was determined to be safe for wheat at 150 g ai/ha in postemergent application, indicating the great potential for 17i development as a herbicide for weed control in wheat fields.


Assuntos
Benzoxazinas/química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Herbicidas/química , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Protoporfirinogênio Oxidase/antagonistas & inibidores , Quinazolinas/química , Benzoxazinas/farmacologia , Desenho de Drogas , Cinética , Proteínas de Plantas/química , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/enzimologia , Protoporfirinogênio Oxidase/química , Relação Quantitativa Estrutura-Atividade , Quinazolinas/farmacologia , Tabaco/efeitos dos fármacos , Tabaco/enzimologia , Controle de Plantas Daninhas
7.
Molecules ; 24(11)2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31174300

RESUMO

In this study, two phenol compounds, magnolol and honokiol, were extracted from Magnolia officinalis and identified by LC-MS, 1H- and 13C-NMR. The magnolol and honokiol were shown to be effective against seven pathogenic fungi, including Alternaria alternata (Fr.) Keissl, Penicillium expansum (Link) Thom, Alternaria dauci f.sp. solani, Fusarium moniliforme J. Sheld, Fusarium oxysporum Schltdl., Valsa mali Miyabe & G. Yamada, and Rhizoctonia solani J.G. Kühn, with growth inhibition of more than 57%. We also investigated the mechanisms underlying the potential antifungal activity of magnolol and honokiol. The results showed that they inhibited the growth of A. alternata in a dose-dependent manner. Moreover, magnolol and honokiol treatment resulted in distorted mycelia and increased the cell membrane permeability of A. alternata, as determined by conductivity measurements. These results suggest that magnolol and honokiol are potential antifungal agents for application against plant fungal diseases.


Assuntos
Compostos de Bifenilo/química , Compostos de Bifenilo/farmacologia , Lignanas/química , Lignanas/farmacologia , Magnolia/efeitos dos fármacos , Doenças das Plantas/microbiologia , Alternaria/efeitos dos fármacos , Alternaria/patogenicidade , Antifúngicos/química , Antifúngicos/farmacologia , Magnolia/química , Tabaco/efeitos dos fármacos , Tabaco/microbiologia
8.
BMC Plant Biol ; 19(1): 253, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31196035

RESUMO

BACKGROUND: Because of their broad applications in our life, nanoparticles are expected to be present in the environment raising many concerns about their possible adverse effects on the ecosystem of plants. The aim of this study was to examine the effect of different sizes and concentrations of iron oxide nanoparticles [(Fe3O4) NPs] on morphological, physiological, biochemical, and ultrastructural parameters in tobacco (Nicotiana tabacum var.2 Turkish). RESULTS: Lengths of shoots and roots of 5 nm-treated plants were significantly decreased in all nanoparticle-treated plants compared to control plants or plants treated with any concentration of 10 or 20 nm nanoparticles. The photosynthetic rate and leaf area were drastically reduced in 5 nm (Fe3O4) NP-treated plants of all concentrations compared to control plants and plants treated with 10 or 20 nm (Fe3O4) NPs. Accumulation of sugars in leaves showed no significant differences between the control plants and plants treated with iron oxide of all sizes and concentrations. In contrast, protein accumulation in plants treated with 5 nm iron oxide dramatically increased compared to control plants. Moreover, light and transmission electron micrographs of roots and leaves revealed that roots and chloroplasts of 5 nm (Fe3O4) NPs-treated plants of all concentrations were drastically affected. CONCLUSIONS: The size and concentration of nanoparticles are key factors affecting plant growth and development. The results of this study demonstrated that the toxicity of (Fe3O4) NPs was clearly influenced by size and concentration. Further investigations are needed to elucidate more about NP toxicity in plants, especially at the molecular level.


Assuntos
Nanopartículas Metálicas , Tabaco/efeitos dos fármacos , Cloroplastos/efeitos dos fármacos , Cloroplastos/ultraestrutura , Relação Dose-Resposta a Droga , Compostos Férricos/farmacologia , Microscopia Eletrônica de Transmissão , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/ultraestrutura , Brotos de Planta/efeitos dos fármacos , Tabaco/metabolismo , Tabaco/ultraestrutura
9.
Plant Physiol Biochem ; 142: 1-7, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31247444

RESUMO

Proline is one of the amino acids that compose proteins and has various roles under non-stress and stress conditions. In this study, we investigated the effect of proline on the growth and browning of two plants, tobacco and rice, by exogenous application and endogenous increase of proline. Exogenous proline had a different effect on the growth and browning between tobacco and rice: proline affected negatively the growth of tobacco seedlings and favorably that of rice seedlings. In addition, proline prevented browning only in rice cultured cells, consistent with the increase of proline contents, but not in tobacco BY-2 cells. These results might be due to the difference of exogenous proline uptake activity in these cells. From the Lineweaver-Burk plots, proline inhibited polyphenol oxidase activity in vitro, which is a major factor of enzymatic browning in plants, by affecting the enzyme-substrate complex. Proline could suppress the browning of the plant callus by inhibition of PPO activity.


Assuntos
Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Prolina/farmacologia , Tabaco/efeitos dos fármacos , Tabaco/crescimento & desenvolvimento , Catecol Oxidase/antagonistas & inibidores , Catecol Oxidase/metabolismo , Células Cultivadas , Malondialdeído/metabolismo , Oryza/citologia , Oryza/genética , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Polifenóis/metabolismo , Prolina/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento
10.
Molecules ; 24(12)2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31212797

RESUMO

We report on two new electrochemical sensors which, coupled to differential pulse voltammetry, constitutes a useful tool for diagnosis of heavy metal pollution. The electrochemical sensors AgHgNf/Cu and the AgBiNf/Cu were obtained by deposition of bimetallic particles of AgHg or AgBi on copper electrodes covered with a Nafion (Nf) film, respectively. Micrographs of the electrode's surface showed evenly scattered bimetallic particles, with an approximate diameter of 150 nm, embedded in the Nafion (Nf) film. In order to test the electrodes, the hydrogen evolution signal according to the Brdicka reaction was measured for the determination of cysteine-rich peptides (CRp) produced by plants. To check the accuracy of the electrodes, real samples of Nicotiana tabacum cells exposed to cytotoxic levels of cadmium were tested. The AgHgNf/Cu electrode produced detection limits (DLs) of 0.088 µmol L-1 for Cysteine and 0.139µmol L-1 for Glutathione, while for the AgBiNf/Cu electrode DLs were 0.41 µmol L-1 for cysteine and 0.244 µmol L-1 for glutathione. Thus, the new electrodes could be a useful analytical electrochemical system very convenient for fieldwork. The electrodes were capable of direct, accurate, and sensitive detection of synthesized peptides, despite the complex matrix where the Nicotiana tabacum cells were grown.


Assuntos
Técnicas Biossensoriais , Cobre , Eletrodos , Nanopartículas Metálicas , Peptídeos , Cádmio/toxicidade , Cobre/química , Cisteína/química , Glutationa/análise , Nanopartículas Metálicas/química , Estrutura Molecular , Peptídeos/análise , Peptídeos/química , Tabaco/química , Tabaco/efeitos dos fármacos , Tabaco/metabolismo
11.
Plant Sci ; 284: 16-24, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31084868

RESUMO

In this paper, we evaluated the genotoxicity of cadmium (Cd) in plants by performing a methylation-sensitive amplification polymorphism (MSAP) on the model plant Nicotiana benthamiana. Among 255 loci examined, 14 genes were found to show altered cytosine methylation patterns in response to Cd stress. Four of those genes (NbMORC3, NbHGSNAT, NbMUT, and NbBG) were selected for further analysis due to their predicted roles in plant development. Cd-induced changes of cytosine methylation status in MSAP fragments of selected genes were confirmed using bisulfite sequencing polymerase chain reaction (BSP). In addition, the expression levels of these genes were found to correlate with cadmium dosage, and a knock-down of these four genes via virus-induced genes silencing (VIGS) led to abnormal development and elevated sensitivity to cadmium stress. Silencing of these four genes resulted in altered cadmium accumulation in different parts of the experimental plants. Our data indicate that cadmium exposure causes dramatic changes in the cytosine methylation status of the plant genome, thus affecting the expression of many genes that are vital for plant growth and are involved in cadmium stress response.


Assuntos
Cádmio/toxicidade , Citosina/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Tabaco/efeitos dos fármacos , DNA de Plantas/efeitos dos fármacos , Genes de Plantas/efeitos dos fármacos , Metilação/efeitos dos fármacos , Reação em Cadeia da Polimerase em Tempo Real , Estresse Fisiológico/efeitos dos fármacos , Tabaco/genética , Tabaco/metabolismo
12.
Int J Mol Sci ; 20(10)2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31091777

RESUMO

Salinity is one of the most severe forms of abiotic stress and affects crop yields worldwide. Plants respond to salinity stress via a sophisticated mechanism at the physiological, transcriptional and metabolic levels. However, the molecular regulatory networks involved in salt and alkali tolerance have not yet been elucidated. We developed an RNA-seq technique to perform mRNA and small RNA (sRNA) sequencing of plants under salt (NaCl) and alkali (NaHCO3) stress in tobacco. Overall, 8064 differentially expressed genes (DEGs) and 33 differentially expressed microRNAs (DE miRNAs) were identified in response to salt and alkali stress. A total of 1578 overlapping DEGs, which exhibit the same expression patterns and are involved in ion channel, aquaporin (AQP) and antioxidant activities, were identified. Furthermore, genes involved in several biological processes, such as "photosynthesis" and "starch and sucrose metabolism," were specifically enriched under NaHCO3 treatment. We also identified 15 and 22 miRNAs that were differentially expressed in response to NaCl and NaHCO3, respectively. Analysis of inverse correlations between miRNAs and target mRNAs revealed 26 mRNA-miRNA interactions under NaCl treatment and 139 mRNA-miRNA interactions under NaHCO3 treatment. This study provides new insights into the molecular mechanisms underlying the response of tobacco to salinity stress.


Assuntos
MicroRNAs/genética , RNA Mensageiro/genética , Tolerância ao Sal , Tabaco/genética , Transcriptoma , Carbonatos/farmacologia , Regulação da Expressão Gênica de Plantas , MicroRNAs/metabolismo , RNA Mensageiro/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/metabolismo
13.
Environ Sci Pollut Res Int ; 26(18): 18053-18070, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31093913

RESUMO

The successful phytoextraction of potentially toxic elements (PTEs) from polluted soils can be achieved by growing non-food and industrial crops. Tobacco (Nicotiana tabacum L.) is one of the main industrial crops and is widely grown in many countries. Tobacco can uptake high concentrations of PTEs especially in aboveground biomass without suffering from toxicity. This review highlighted the potential of tobacco for the phytoextraction of heavy metals and tolerance mechanisms under metal stress. Different management practices have been discussed which can enhance the potential of this plant for metal extraction. Finally, suitable options for the management/disposal of biomass enriched in excess metal have been elaborated to prevent secondary pollution.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Tabaco/crescimento & desenvolvimento , Biodegradação Ambiental , Biomassa , Metais Pesados/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/metabolismo
14.
PLoS One ; 14(5): e0217204, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31116769

RESUMO

It is well known that exogenous trehalose can improve resistances of plants to some abiotic and biotic stresses. Nonetheless, information respecting the molecular responses of tobacco leaves to Tre treatment is limited. Here we show that exogenous Tre can rapidly reduce stomatal aperture, up-regulate NADPH oxidase genes and increase O2•-andH2O2 on tobacco leaves at 2 h after treatment. We further demonstrated that imidazole and DPI, inhibitors of NADPH oxidase, can promote recovery of stomatal aperture of tobacco leaves upon trehalose treatment. Exogenous trehalose increased tobacco leaf resistance to tobacco mosaic disease significantly in a concentration-dependent way. To elucidate the molecular mechanisms in response to exogenous trehalose, the transcriptomic responses of tobacco leaves with 10 (low concentration) or 50 (high concentration) mM of trehalose treatment at 2 or 24h were investigated through RNA-seq approach. In total, 1288 differentially expressed genes (DEGs) were found with different conditions of trehalose treatments relative to control. Among them, 1075 (83.5%) were triggered by low concentration of trehalose (10mM), indicating that low concentration of Tre is a better elicitor. Functional annotations with KEGG pathway analysis revealed that the DEGs are involved in metabolic pathway, biosynthesis of secondary metabolites, plant hormone signal transduction, plant-pathogen interaction, protein processing in ER, flavonoid synthesis and circadian rhythm and so on. The protein-protein interaction networks generated from the core DEGs regulated by all conditions strikingly revealed that eight proteins, including ClpB1, HSP70, DnaJB1-like protein, universal stress protein (USP) A-like protein, two FTSH6 proteins, GolS1-like protein and chloroplastics HSP, play a core role in responses to exogenous trehalose in tobacco leaves. Our data suggest that trehalose triggers a signal transduction pathway which involves calcium and ROS-mediated signalings. These core components could lead to partial resistance or tolerance to abiotic and biotic stresses. Moreover, 19 DEGs were chosen for analysis of quantitative real-time polymerase chain reaction (qRT-PCR). The qRT-PCR for the 19 candidate genes coincided with the DEGs identified via the RNA-seq analysis, sustaining the reliability of our RNA-seq data.


Assuntos
Redes Reguladoras de Genes , Folhas de Planta/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico , Tabaco/genética , Transcriptoma/efeitos dos fármacos , Trealose/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Tabaco/efeitos dos fármacos , Tabaco/fisiologia
15.
PLoS Pathog ; 15(5): e1007771, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31136641

RESUMO

Positive-stranded RNA viruses replicate inside cells and depend on many co-opted cellular factors to complete their infection cycles. To combat viruses, the hosts use conserved restriction factors, such as DEAD-box RNA helicases, which can function as viral RNA sensors or as effectors by blocking RNA virus replication. In this paper, we have established that the plant DDX17-like RH30 DEAD-box helicase conducts strong inhibitory function on tombusvirus replication when expressed in plants and yeast surrogate host. The helicase function of RH30 was required for restriction of tomato bushy stunt virus (TBSV) replication. Knock-down of RH30 levels in Nicotiana benthamiana led to increased TBSV accumulation and RH30 knockout lines of Arabidopsis supported higher level accumulation of turnip crinkle virus. We show that RH30 DEAD-box helicase interacts with p33 and p92pol replication proteins of TBSV, which facilitates targeting of RH30 from the nucleus to the large TBSV replication compartment consisting of aggregated peroxisomes. Enrichment of RH30 in the nucleus via fusion with a nuclear retention signal at the expense of the cytosolic pool of RH30 prevented the re-localization of RH30 into the replication compartment and canceled out the antiviral effect of RH30. In vitro replicase reconstitution assay was used to demonstrate that RH30 helicase blocks the assembly of viral replicase complex, the activation of the RNA-dependent RNA polymerase function of p92pol and binding of p33 replication protein to critical cis-acting element in the TBSV RNA. Altogether, these results firmly establish that the plant DDX17-like RH30 DEAD-box helicase is a potent, effector-type, restriction factor of tombusviruses and related viruses. The discovery of the antiviral role of RH30 DEAD-box helicase illustrates the likely ancient roles of RNA helicases in plant innate immunity.


Assuntos
Antivirais/farmacologia , RNA Helicases DEAD-box/farmacologia , Proteínas de Plantas/metabolismo , Tabaco/virologia , Tombusvirus/efeitos dos fármacos , Proteínas Virais/metabolismo , Replicação Viral/efeitos dos fármacos , Arabidopsis/metabolismo , Arabidopsis/virologia , Interações Hospedeiro-Patógeno , Doenças das Plantas/virologia , Proteínas de Plantas/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/metabolismo , Tombusvirus/fisiologia , Proteínas Virais/genética , Montagem de Vírus/efeitos dos fármacos
16.
Plant Physiol Biochem ; 139: 435-445, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30999131

RESUMO

Recent years have witnessed a renewed interest in introns as a tool to increase gene expression. We previously isolated TdSHN1 gene encoding a transcription factor in durum wheat. Here we show that TdSHN1 intron contains many CT-stretches and the motif CGATT known to be important for IME. When subjected to bioinformatics analysis using IMEter software, TdSHN1 intron obtained a score of 17.04 which indicates that it can moderately enhance gene expression. TdSHN1 gene including its intron was placed under the control of TdSHN1 endogenous salt and drought-inducible promoter or the constitutive 35S promoter and transferred into tobacco. Transgenic lines were obtained and designated gD (with 35S promoter) and PI (with native promoter). A third construct was also used in which intron-less cDNA was driven by the 35S promoter (cD lines). Results showed that, gD lines exhibited lower stomatal density than cD lines. When subjected to drought and salt stresses, gD lines outperformed intron-less cD lines and WT. Indeed, gD lines exhibited longer roots, higher biomass production, retained more chlorophyll, produced less ROS and MDA and had higher antioxidant activity. qRT-PCR analysis revealed that gD lines had higher TdSHN1 expression levels than cD lines. In addition, expression of ROS-scavengering, stress-related and wax biosynthesis tobacco genes was higher in gD lines compared to cD lines and WT. Interestingly, under stress conditions, PI transgenic lines showed higher TdSHN1 expression levels and outperformed gD lines. These results suggest that TdSHN1 intron enhances gene expression when used alone or in combination with TdSHN1 endogenous promoter.


Assuntos
Íntrons/genética , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas/genética , Tabaco/genética , Secas , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Tolerância ao Sal/genética , Cloreto de Sódio/farmacologia , Tabaco/efeitos dos fármacos , Tabaco/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
Int J Mol Sci ; 20(7)2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30935036

RESUMO

Systemic acquired resistance (SAR) induction is one of the primary defence mechanisms of plants against a broad range of pathogens. It can be induced by infectious agents or by synthetic molecules, such as benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH). SAR induction is associated with increases in salicylic acid (SA) accumulation and expression of defence marker genes (e.g., phenylalanine ammonia-lyase (PAL), the pathogenesis-related (PR) protein family, and non-expressor of PR genes (NPR1)). Various types of pathogens and pests induce plant responses by activating signalling pathways associated with SA, jasmonic acid (JA) and ethylene (ET). This work presents an analysis of the influence of BTH and its derivatives as resistance inducers in healthy and virus-infected plants by determining the expression levels of selected resistance markers associated with the SA, JA, and ET pathways. The phytotoxic effects of these compounds and their influence on the course of viral infection were also studied. Based on the results obtained, the best-performing BTH derivatives and their optimal concentration for plant performance were selected, and their mode of action was suggested. It was shown that application of BTH and its derivatives induces increased expression of marker genes of both the SA- and JA-mediated pathways.


Assuntos
Resistência à Doença/efeitos dos fármacos , Tiadiazóis/farmacologia , Tabaco/imunologia , Ciclopentanos/metabolismo , Etilenos/metabolismo , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/virologia , Tobamovirus/patogenicidade
18.
Int J Mol Sci ; 20(7)2019 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-30935160

RESUMO

Greenhouse hydroponic experiments were conducted using Cd-sensitive (cv. Guiyan1) and Cd-tolerant (cv. Yunyan2) tobacco cultivars to study the ameliorative effects of exogenous glycinebetaine (GB) upon 5 µM Cd stress. The foliar spray of GB markedly reduced Cd concentrations in plants and alleviated Cd-induced soil plant analysis development (SPAD) value, plant height and root length inhibition, with the mitigation effect being more obvious in Yunyan2. External GB markedly reduced Cd-induced malondialdehyde (MDA) accumulation, induced stomatal closure, ameliorated Cd-induced damages on leaf/root ultrastructure, and increased the chlorophyll content and fluorescence parameters of Fo, Fm, and Fv/Fm in both cultivars and Pn in Yunyan2. Exogenous GB counteracted Cd-induced alterations of certain antioxidant enzymes and nutrients uptake, e.g., the depressed Cd-induced increase of superoxide dismutase (SOD) and peroxidase (POD) activities, but significantly elevated the depressed catalase (CAT) and ascorbate peroxidase (APX) activities. The results indicate that alleviated Cd toxicity by GB application is related to the reduced Cd uptake and MDA accumulation, balanced nutrients and antioxidant enzyme activities, improved PSII, and integrated ultrastructure in tobacco plants.


Assuntos
Betaína/farmacologia , Cádmio/toxicidade , Tabaco/metabolismo , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Clorofila/metabolismo , Genótipo , Malondialdeído/metabolismo , Peroxidase/metabolismo , Fotossíntese/efeitos dos fármacos , Fotossíntese/genética , Superóxido Dismutase/metabolismo , Tabaco/efeitos dos fármacos , Tabaco/genética
19.
Phytopathology ; 109(7): 1257-1269, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30920357

RESUMO

Ubiquitin (Ub) extension proteins (UEPs) are fusion proteins of a Ub at the N terminus to a ribosomal protein. They are the main source of Ub and the only source of extension ribosomal protein. Although important roles of the Ub-26S proteasome system in various biological processes have been well established, direct evidence for the role of UEP genes in plant defense is rarely reported. In this study, we cloned a Ub-S27a-type UEP gene (NbUEP1) from Nicotiana benthamiana and demonstrated its function in cell death and disease resistance. Virus-induced gene silencing of NbUEP1 led to intensive cell death, culminating in whole-seedling withering. Transient RNA interference (RNAi) of NbUEP1 caused strong cell death in infiltrated areas, while stable NbUEP1-RNAi tobacco plants constitutively formed necrotic lesions in leaves. NbUEP1-RNAi plants exhibited increased resistance to the oomycete Pythium aphanidermatum and viruses Tobacco mosaic virus and Cucumber mosaic virus while displaying decreased resistance to the nematode Meloidogyne incognita compared with non-RNAi control plants. Transcription profiling analysis indicated that jasmonate and ethylene pathways, lipid metabolism, copper amine oxidase-mediated active species generation, glycine-rich proteins, vacuolar processing enzyme- and RD21-mediated cell death and defense regulation, and autophagy might be associated with NbUEP1-mediated cell death and resistance. Our results provided evidence for the important roles of plant UEPs in modulating plant cell death and disease resistance.


Assuntos
Doenças das Plantas/microbiologia , Proteínas de Plantas , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Tabaco , Animais , Morte Celular , Resistência à Doença , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/efeitos dos fármacos , Tabaco/efeitos dos fármacos , Tabaco/crescimento & desenvolvimento , Ubiquitinas
20.
Plant Physiol Biochem ; 139: 179-190, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30901576

RESUMO

The effect of silicon (Si) on tobacco (Nicotiana benthamiana) development and dodder (Cuscuta europaea) - tobacco interaction were studied. Three Si application approaches were tested: tobacco seed priming (2.5 mM Si and 5 mM Si; 2.5S, 5S), watering tobacco plants with Si solution (2.5 mM Si and 5 mM Si; 2.5W, 5W) and foliar application (1 mM Si and 2.5 mM Si; 1F, 2.5F). Dodder was not able to infect the host plant in almost all Si treatments. Only in the control and 2.5W treatments was dodder able to infect its host. A significant increase in all observed antioxidant enzymes activities (POX, CAT and SOD) occurred in the plants of 2.5W treatment after infection in comparison with the uninfected 2.5W treatment and control plants, which indicated the importance of antioxidant enzymes activities in the plant parasite - host interaction. Resistance of Si treated plants to dodder could have been due to the changes in the cell wall properties of the epidermis and cortex where activity of POX was confirmed histochemically. The growth and development of tobacco shoots were evaluated after four and eight weeks of cultivation in the individual Si treatments. The development of shoots was enhanced after eight weeks of cultivation in the 2.5S, 5S, 2.5W and 5W treatments in comparison with the control treatment. However, a negative effect of Si was observed in 1F and 2.5F treatments. In the majority of cases, the plants treated with Si had decreased chlorophyll content when compared to control, except for chl a in 5W plants after 8 weeks of cultivation. Contrary to this, carotenoids increased in all Si treated plants after eight weeks cultivation in comparison with the control. The secondary xylem formation in tobacco was enhanced after 4 and 8 weeks cultivation in shoots of plants receiving the 2.5S, 5S, 2.5W and 5W treartments. The cambium was the most active in producing secondary xylem in the 2.5S treatment. Protein profile and antioxidant enzymes activities (POX, CAT and SOD) were altered by Si treatment. After 8 weeks of cultivation, activities of POX were significantly decreased in 2.5S, 5S, 2.5W and 5W in comparison with control. Catalase was decreased in 2.5S, 5S and 5W in comparison with the control, however, 1F and 2.5F treatments had significantly increased CAT and SOD activities. The specific activity of POX was confirmed histochemically in Si treated plants in the cell walls of several stem tissues like the epidermis, cortex and pith. A small amount of H2O2 was detected in leaves in the control and Si treated plants. The amount of O2- decreased in all treatments with time. The highest Si concentration in the plants (almost 800 mg . kg-1 d. w.) was detected in the 2.5W, 5W treatments.


Assuntos
Cuscuta , Silício/farmacologia , Tabaco/parasitologia , Antioxidantes/metabolismo , Catalase/metabolismo , Parede Celular/efeitos dos fármacos , Cuscuta/crescimento & desenvolvimento , Peroxidase/metabolismo , Caules de Planta/efeitos dos fármacos , Sementes/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Tabaco/efeitos dos fármacos
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