scholarly journals Óleos essenciais no controle da pinta bacteriana e na ativação de respostas bioquímicas em tomateiro

2017 ◽  
Vol 43 (3) ◽  
pp. 212-217 ◽  
Author(s):  
Érika Oliveira da Silva ◽  
Eduardo Alves ◽  
Thiago Costa Ferreira ◽  
Carlos Alberto Cavalcante de Albuquerque
Keyword(s):  
Pseudomonas Syringae ◽  
Santa Cruz ◽  
Cymbopogon Citratus

RESUMO O objetivo deste trabalho foi avaliar o efeito dos óleos essenciais (OEs) de Cymbopogon sp. (Critonela - CI) e Cymbopogon citratus (Capim limão - CL) na redução da pinta bacteriana (Pseudomonas syringae pv. tomato- Pst) e na ativação de algumas respostas bioquímicas de defesa em tomateiro. Foi realizado um teste in vitro para avaliar a presença ou ausência do halo de inibição de Pst pelos OEs, um experimento in vivo para avaliar a melhor concentração desses dois óleos para o controle da pinta bacteriana e um experimento para avaliar o potencial desses óleos e do acibenzolar-S-metil na ativação de algumas respostas bioquímicas em planta de tomate (cv. Santa Cruz). Halos de inibição foram observados para os OEs de CI e CLa partir da concentração de 1%.Os óleos essenciais de CI a uma concentração de 2.000 µL L-1 e CL na concentração de 1.500 µL L-1, bem como o ASM 0,2g L-1 foram eficientes no controle da pinta bacteriana quando aplicados em uma única vez sete dias antes da inoculação do patógeno. O óleo essencial de CI e o ASM conferiram capacidade parcial de proteção em plantas de tomateiro desafiadas por Pst. Os óleos e o ASM também promoveram um aumento na quantidade de fenol total e lignificação da parede celular. Portanto por meio dos resultados obtidos neste trabalho foi demonstrado que existe um potencial uso de OEs no controle da pinta bacteriana do tomateiro, evidenciando a indução de resistência como o principal modo de ação atuante.

scholarly journals Controle da ferrugem das folhas do capim-limão [Cymbopogon citratus (DC: ) Stapf] com produtos naturais

2012 ◽  
Vol 14 (4) ◽  
pp. 571-578 ◽  
Author(s):  
E.R. Lorenzetti ◽  
D.M. Conceição ◽  
L.V.S. Sacramento ◽  
E.L. Furtado
Keyword(s):  
Cymbopogon Citratus

Cymbopogon citratus (DC.) Stapf é uma planta medicinal pertencente a família Poaceae, perene, importante para a indústria farmacêutica e alimentícia devido ao óleo essencial que produz. Um problema limitante para a produção comercial é a ferrugem, doença cujo agente etiológico é o fungo Puccinia nakanishikii Dietel. O presente trabalho objetivou avaliar a ação de produtos naturais no controle da doença in vitro e in vivo. Para os testes in vitro, empregaram-se os seguintes produtos sobre a germinação de esporos do patógeno: óleos essenciais de eucalipto, palma-rosa, cravo-da-índia, menta, limão, citronela e mil-folhas; extrato pirolenhoso de eucalipto e mentol cristalizado, em diferentes concentrações. Para os testes de campo foram selecionados quatro produtos, o óleo de citronela e de eucalipto, o extrato pirolenhoso, e o mentol. In vitro, todos os agentes mostraram-se promissores no controle do patógeno. Quando em condições in vivo, sob alta severidade da doença no ato da avaliação, os produtos testados foram capazes de reduzir a severidade da doença em comparação com a testemunha. O controle da doença com os agentes naturais variou de 38% (extrato pirolenhoso) a 61%(óleo essencial de eucalipto).

scholarly journals Effectiveness of Dunaliella salina Extracts against Bacillus subtilis and Bacterial Plant Pathogens

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 613
Author(s):  
Alfredo Ambrico ◽  
Mario Trupo ◽  
Rosaria Magarelli ◽  
Roberto Balducchi ◽  
Angelo Ferraro ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Pseudomonas Syringae ◽  
Dunaliella Salina ◽  
Plant Pathogens ◽  
Plant Diseases ◽  
Economic Losses ◽  
Tomato Plants ◽  
Hexane Extracts

Several bacteria pathogens are responsible for plant diseases causing significant economic losses. The antibacterial activity of Dunaliella salina microalgae extracts were investigated in vitro and in vivo. First, biomass composition was chemically characterized and subjected to extraction using polar/non-polar solvents. The highest extraction yield was obtained using chloroform:methanol (1:1 v/v) equal to 170 mg g−1 followed by ethanol (88 mg g−1) and hexane (61 mg g−1). In vitro examination of hexane extracts of Dunaliella salina demonstrated antibacterial activity against all tested bacteria. The hexane extract showed the highest amount of β-carotene with respect to the others, so it was selected for subsequent analyses. In vivo studies were also carried out using hexane extracts of D. salina against Pseudomonas syringae pv. tomato and Pectobacterium carotovorum subsp. carotovorum on young tomato plants and fruits of tomato and zucchini, respectively. The treated young tomato plants exhibited a reduction of 65.7% incidence and 77.0% severity of bacterial speck spot disease. Similarly, a reduction of soft rot symptoms was observed in treated tomato and zucchini fruits with a disease incidence of 5.3% and 12.6% with respect to 90.6% and 100%, respectively, for the positive control.

scholarly journals A putative nuclear copper chaperone promotes plant immunity in Arabidopsis

2020 ◽  
Vol 71 (20) ◽  
pp. 6684-6696 ◽  
Author(s):  
Long-Xiang Chai ◽  
Kai Dong ◽  
Song-Yu Liu ◽  
Zhen Zhang ◽  
Xiao-Peng Zhang ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Copper Chaperone ◽  
Copper Binding ◽  
Nuclear Speckles ◽  
Defense Gene Expression ◽  
Copper Chaperones ◽  
Plant Nucleus

Abstract Copper is essential for many metabolic processes but must be sequestrated by copper chaperones. It is well known that plant copper chaperones regulate various physiological processes. However, the functions of copper chaperones in the plant nucleus remain largely unknown. Here, we identified a putative copper chaperone induced by pathogens (CCP) in Arabidopsis thaliana. CCP harbors a classical MXCXXC copper-binding site (CBS) at its N-terminus and a nuclear localization signal (NLS) at its C-terminus. CCP mainly formed nuclear speckles in the plant nucleus, which requires the NLS and CBS domains. Overexpression of CCP induced PR1 expression and enhanced resistance against Pseudomonas syringae pv. tomato DC3000 compared with Col-0 plants. Conversely, two CRISPR/Cas9-mediated ccp mutants were impaired in plant immunity. Further biochemical analyses revealed that CCP interacted with the transcription factor TGA2 in vivo and in vitro. Moreover, CCP recruits TGA2 to the PR1 promoter sequences in vivo, which induces defense gene expression and plant immunity. Collectively, our results have identified a putative nuclear copper chaperone required for plant immunity and provided evidence for a potential function of copper in the salicylic pathway.

scholarly journals Anthelmintic activity of Cymbopogon citratus against Haemonchus contortus

2015 ◽  
Vol 24 (3) ◽  
pp. 268-275 ◽  
Author(s):  
Iara Tersia Freitas Macedo ◽  
Lorena Mayana Beserra de Oliveira ◽  
Wesley Lyeverton Correia Ribeiro ◽  
Jessica Maria Leite dos Santos ◽  
Kaline das Chagas Silva ◽  
...  
Keyword(s):  
Essential Oil ◽  
Haemonchus Contortus ◽  
Anthelmintic Activity ◽  
Meriones Unguiculatus ◽  
Parasitic Nematodes ◽  
Control Group ◽  
Cymbopogon Citratus ◽  
Egg Hatching

Parasitic nematodes are of major economic importance in livestock. An alternative for the control of parasites is phytotherapy. This study evaluated the efficacy of Cymbopogon citratus decoction (CcD), C. citratus essential oil (CcEo) and citral against Haemonchus contortus using in vitro egg hatch test (EHT) and larval development test (LDT) and an in vivo test using a Meriones unguiculatus (gerbil) model. The effect of 800 mg/kg CcEo was evaluated in gerbils that had been artificially infected with 5,000 third-stage H. contortus larvae. The effective concentrations required to inhibit 50% (EC50) of egg hatching were 0.46, 0.14 and 0.13 mg/mL for CcD, CcEo and citral, respectively. The EC50 values in the LDT were 5.04, 1.92 and 1.37 mg/mL for CcD, CcEo and citral, respectively. H. contortus population in the group treated with C. citratus essential oil was reduced by 38.5% (P< 0.05) in comparison to the control group. These results suggest that it may be possible to use C. citratusessential oil to control of H. contortus parasite of small ruminant.

scholarly journals Controle da antracnose em maracujá-amarelo por derivados de capim-limão (Cymbopogon citratus)

2012 ◽  
Vol 79 (3) ◽  
pp. 371-379 ◽  
Author(s):  
G.S Moura ◽  
K.R.F Schwan-Estrada ◽  
A.P.F Alves ◽  
G Franzener ◽  
J.R Stangarlin
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Cymbopogon Citratus

O maracujá-amareloé uma das principais frutíferas cultivadas no Brasil. A conservação pós-colheita de frutos de maracujá tem merecido grande atenção visto que o fruto é perecível e está sujeito à rápida deterioração e incidência de micro-organismos patogênicos. Este trabalho teve por objetivo avaliar a atividade antifúngica in vitro de derivados de capim-limão (Cymbopogon citratus) sobre o crescimento micelial, esporulação, germinação de esporos e tamanho de tubos germinativos de Colletotrichum gloeosporioides e in vivo no controle da antracnose sobre frutos de maracujá-amarelo em pós-colheita. Os tratamentos para o ensaio in vitro foram óleo essencial (OE) (0,5, 1, 5, 10, 15, 25, 50 e 60 µL mL-1), extrato bruto aquoso autoclavado (EAA), extrato bruto aquoso filtrado (EAF), hidrolato e citral (1, 5, 10, 20 e 25%) e no ensaio in vivo, os frutos foram tratados com: OE (0,025; 0,05 e 0,1%), hidrolato (5 e 10%), EAA (10%) e citral (0,1%). Água destilada foi utilizada como testemunha. Foram avaliadas a incidência e a severidade da antracnose a cada três dias. Os quatro derivados de capim-limão inibiram o crescimento micelial, a esporulação e a germinação de esporos, sendo que maiores valores de inibição foram obtidos nas maiores concentrações testadas e, no crescimento micelial, atingiram 55,8; 54,5; 30,0 e 19,9% para OE, EAF, EAA e hidrolato, respectivamente. Na avaliação in vivo, OE 0,1% e EAA 10% promoveram significativa redução na severidade da antracnose.

scholarly journals Characterisation, Manipulation and Directed Evolution of Non-Ribosomal Peptide Synthetase Enzymes

2021 ◽  
Author(s):  
◽  
Jeremy George Owen
Keyword(s):  
Amino Acid ◽  
Directed Evolution ◽  
Pseudomonas Syringae ◽  
Gene Knockout ◽  
Iron Starvation ◽  
Biochemical Characterisation ◽  
T Domain ◽  
Stereo Selectivity

<p><b>Non-ribosomal peptide synthetases (NRPS) are large, modular enzymes that synthesisebiologically active secondary metabolites from amino acid precursors without the need for anucleic acid template. NRPS play an integral role in microbial physiology and also havepotential applications in the synthesis of novel peptide molecules. Both of these aspects areexamined in this thesis.</b></p> <p>Under conditions of iron starvation Pseudomonas syringae synthesises siderophores for activeuptake of iron. The primary siderophore of P. syringae is pyoverdine, a fluorescent moleculethat is assembled from amino acid (aa) precursors by NRPS. Five putative pyoverdine NRPSgenes in P. syringae pv. phaseolicola 1448a (Ps1448a) were identified and characterised insilico and their role in pyoverdine biosynthesis was confirmed by gene knockout. Creation ofpyoverdine null Ps1448a enabled identification of a previously uncharacterised temperatureregulatedsecondary siderophore, achromobactin, which is NRPS independent and has loweraffinity for iron. Pyoverdine and achromobactin null mutants were characterised in regard toiron uptake, virulence and growth in iron-limited conditions. Determination of the substratespecificity for the seven adenylation (A) domains of the Ps1448a pyoverdine sidechain NRPSwas also attempted. Although ultimately unsuccessful, these attempts provided a rigorousassessment of methods for the expression, purification and biochemical characterisation of Adomains.</p> <p>The Ps1448a NRPS were subsequently employed in domain swapping experiments to testcondensation (C) domain specificity for aa substrates during peptide formation in vivo.</p> <p>Experiments in which the terminal C- and/or A-domain of the Pseudomonas aeruginosa(PAO1) pyoverdine NRPS system were replaced with alternative domains from Ps1448a andPAO1 were consistent with previous in vitro observations that C-domains exhibit strongsidechain and stereo-selectivity at the downstream aa position, but only stereo-selectivity atthe upstream aa position.</p> <p>These results prompted investigation into the role of inter-domain communication in NRPSfunction, to test the hypothesis that the thiolation (T) domain enters into specific interactionswith other domains, which might provide an alternative explanation for the diminished activityof recombinant NRPS enzymes. A recently characterised single-module NRPS, bpsA, waschosen as a reporter gene for these experiments based on its ability to generate blue pigment inEscherichia coli. Substitution of the native bpsA T-domain consistently impaired function,consistent with the hypothesis. It was shown that directed evolution could be applied to restorefunction in substituted T-domains. Mutations that restored function were mapped in silico, anda structural model for interaction between the thioester (TE) and T-domain of BpsA wasderived.</p> <p>The utility of bpsA for discovery and characterisation of phosphopantetheinyl transferase(PPTase) enzymes was also investigated. In vivo and in vitro assays for determination ofPPTase activity were developed and a high-throughput screen for discovery of new PPTases inenvironmental DNA libraries was successfully implemented.</p>

scholarly journals Evaluation of bacteriophages in the biocontrol of Pseudomonas syringae pv. syringae isolated from cankers on sweet cherry (Prunus avium L.) in Turkey

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Mustafa Akbaba ◽  
Hatice Ozaktan
Keyword(s):  
Pseudomonas Syringae ◽  
Pathogenic Bacteria ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Bacterial Canker ◽  
Productivity Losses ◽  
Pathogenicity Tests ◽  
Phenotypic Tests

Abstract Background Bacterial canker and subsequent gummosis are caused by multiple pathogens and lead to significant yield and productivity losses in sweet cherry cultivation in Turkey. This study identified that Pseudomonas syringae pathovars were responsible for bacterial canker on sweet cherry orchards by using classical and molecular methods and evaluated the biocontrol effects of bacteriophages against P. syringae pv. syringae. Results Pathogenic bacteria were isolated from samples taken from plants showing symptoms of bacterial canker in cherry orchards located in İzmir and Manisa provinces. Specific pathogens were identified using pathogenicity, phenotypic tests, and simplex PCR. Bacteriophages effective against P. syringae strains were isolated from soil contaminated with pathogens identified in the diseased orchards using an optimized isolation protocol. The biocontrol activity of bacteriophage isolates against P. syringae pv. syringae was tested in vitro and in vivo. The results of pathogenicity tests on immature sweet cherry fruits and micropropagated cherry plantlets revealed 10 pathogenic bacteria isolates from 44 plant samples taken from sweet cherry orchards showing symptoms of bacterial canker. Conclusions Ten isolates were identified as Pseudomonas syringae pv. syringae. Nine different pure bacteriophage isolates were effective. The results indicated that bacteriophage isolates may demonstrate variable reactivity against P. syringae pathovars.

scholarly journals Glucosylation of Salicylic Acid in Nicotiana tabacum Cv. Xanthi-nc

1998 ◽  
Vol 88 (7) ◽  
pp. 692-697 ◽  
Author(s):  
Hyung-il Lee ◽  
Ilya Raskin
Keyword(s):  
Salicylic Acid ◽  
Nicotiana Tabacum ◽  
Pseudomonas Syringae ◽  
Gel Filtration ◽  
High Concentration ◽  
Maximal Level ◽  
Minor Metabolite ◽  
Continuous Accumulation

Salicylic acid (SA) is a key regulatory component of disease resistance in plants. In tobacco mosaic virus (TMV)-inoculated tobacco (Nicotiana tabacum cv. Xanthi-nc NN genotype), newly synthesized SA is converted primarily to SA 2-O-β-D-glucoside (SAG) and glucosyl salicylate (GS), a relatively minor metabolite. Similar patterns in the formation of GS and SAG were observed in tobacco inoculated with Pseudomonas syringae pv. phaseolicola, suggesting the accumulation of two glucosylated metabolites is a general phenomenon in tobacco plants. After SA infiltration, GS was synthesized rapidly, reached a maximal level at 6 h, declined, and remained relatively constant for at least 24 h. In contrast, SAG content increased gradually after SA treatment. Our in vitro and in vivo data suggest that a high concentration of free SA triggers transient formation of GS and continuous accumulation of SAG, which is a more stable metabolite of SA. The two distinct SA glucosyltransferases catalyzed the formation of GS and SAG, respectively. The activities of these enzymes were enhanced by TMV or P. syringae pv. phaseolicola inoculation or SA treatment and were found in different fractions of gel filtration chromatography.

scholarly journals The Alternative Sigma Factor RpoN Is Required for hrpActivity in Pseudomonas syringae pv. Maculicola and Acts at the Level of hrpL Transcription

2000 ◽  
Vol 182 (12) ◽  
pp. 3508-3516 ◽  
Author(s):  
Erik L. Hendrickson ◽  
Pablo Guevera ◽  
Frederick M. Ausubel
Keyword(s):  
Pseudomonas Syringae ◽  
Transcriptional Activity ◽  
Constitutive Expression ◽  
Wild Type ◽  
In Planta ◽  
Disease Symptoms ◽  
Nicotiana Tobacum ◽  
Mutant Strains

ABSTRACT β-Glucuronidase (uidA) reporter gene fusions were constructed for the hrpZ, hrpL, andhrpS genes from the phytopathogen Pseudomonas syringae pv. maculicola strain ES4326. These reporters, as well as an avrRpt2-uidA fusion, were used to measure transcriptional activity in ES4326 and a ES4326 rpoNmutant. rpoN was required for the expression ofavrRpt2, hrpZ, and hrpL in vitro in minimal media and in vivo when infiltrated into Arabidopsis thaliana leaves. In contrast, the expression of hrpSwas essentially the same in wild-type and rpoN mutant strains. Constitutive expression of hrpL in anrpoN mutant restored hrpZ transcription to wild-type levels, restored the hypersensitive response when infiltrated into tobacco (Nicotiana tobacum), and partially restored the elicitation of virulence-related symptoms but not growth when infiltrated into Arabidopsis leaves. These data indicate that rpoN-mediated control of hrp gene expression acts at the level of hrpL and that in planta growth of P. syringae is not required for the elicitation of disease symptoms.

scholarly journals The type III effector HopF2Pto targets Arabidopsis RIN4 protein to promote Pseudomonas syringae virulence

2010 ◽  
Vol 107 (5) ◽  
pp. 2349-2354 ◽  
Author(s):  
Mike Wilton ◽  
Rajagopal Subramaniam ◽  
James Elmore ◽  
Corinna Felsensteiner ◽  
Gitta Coaker ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Effector Proteins ◽  
Type Iii ◽  
Pathogen Effector ◽  
Effector Triggered Immunity ◽  
Type Iii Secretion Effector ◽  
Virulence Target

Plant immunity can be induced by two major classes of pathogen-associated molecules. Pathogen- or microbe-associated molecular patterns (PAMPs or MAMPs) are conserved molecular components of microbes that serve as “non-self” features to induce PAMP-triggered immunity (PTI). Pathogen effector proteins used to promote virulence can also be recognized as “non-self” features or induce a “modified-self” state that can induce effector-triggered immunity (ETI). The Arabidopsis protein RIN4 plays an important role in both branches of plant immunity. Three unrelated type III secretion effector (TTSE) proteins from the phytopathogen Pseudomonas syringae, AvrRpm1, AvrRpt2, and AvrB, target RIN4, resulting in ETI that effectively restricts pathogen growth. However, no pathogenic advantage has been demonstrated for RIN4 manipulation by these TTSEs. Here, we show that the TTSE HopF2Pto also targets Arabidopsis RIN4. Transgenic plants conditionally expressing HopF2Pto were compromised for AvrRpt2-induced RIN4 modification and associated ETI. HopF2Pto interfered with AvrRpt2-induced RIN4 modification in vitro but not with AvrRpt2 activation, suggestive of RIN4 targeting by HopF2Pto. In support of this hypothesis, HopF2Pto interacted with RIN4 in vitro and in vivo. Unlike AvrRpm1, AvrRpt2, and AvrB, HopF2Pto did not induce ETI and instead promoted P. syringae growth in Arabidopsis. This virulence activity was not observed in plants genetically lacking RIN4. These data provide evidence that RIN4 is a major virulence target of HopF2Pto and that a pathogenic advantage can be conveyed by TTSEs that target RIN4.

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