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1.
J Agric Food Chem ; 68(8): 2306-2315, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-31995378

RESUMO

Neocryptolepine is an alkaloid isolated from traditional African herbal medicine Cryptolepis sanguinolenta, and its broad spectrum of biological activities has been illuminated in past decades. In this study, neocryptolepine and its derivatives (1-49) were designed and synthesized from economical and readily available starting materials. Their structures were confirmed by proton nuclear magnetic resonance, carbon nuclear magnetic resonance, and mass spectrometry. The synthesized compounds were screened for their antifungal profile against six agriculturally important fungi Rhizoctonia solani, Botrytis cinerea (B. cinerea), Fusarium graminearum, Mycosphaerella melonis, Sclerotinia sclerotiorum, and Magnaporthe oryzae. The results of in vitro assay revealed that compounds 5, 21, 24, 35, 40, 45, and 47 presented remarkable antifungal activity against the fungi tested with EC50 values lower than 1 µg/mL. Significantly, compound 24 displayed the most effective inhibitory potency against B. cinerea (EC50 = 0.07 µg/mL), and the data from in vivo experiments revealed that compound 24 demonstrated comparable protective activity with the positive control boscalid. Preliminary mechanism studies indicated that compound 24 showed impressive spore germination inhibitory effectiveness and lower cytotoxicity than azoxystrobin, imparted on normal function of the cell membrane and cell wall, and arrested the normal function of the nucleus. Besides the excellent inhibitory activity against agriculturally important phytopathogenic fungi tested, the designed assemblage possesses several benefits with a high profile of variation in synthesized molecules, the ease of synthesis, and good cost-effectiveness of commercially available synthetic reagents, all of these have highlighted the potential worth of compound 24 as a new and highly efficient agricultural fungicide.


Assuntos
Antifúngicos/farmacologia , Fungicidas Industriais/farmacologia , Doenças das Plantas/microbiologia , Antifúngicos/síntese química , Antifúngicos/química , Botrytis/efeitos dos fármacos , Botrytis/crescimento & desenvolvimento , Fungicidas Industriais/síntese química , Fungicidas Industriais/química , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Estrutura Molecular , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/crescimento & desenvolvimento , Relação Estrutura-Atividade
2.
J Appl Microbiol ; 128(1): 255-264, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31541488

RESUMO

AIMS: To conduct molecular tagging of the biocontrol fungus Trichoderma asperellum strain T4 and elucidate its colonization patterns in soil. METHODS AND RESULTS: We constructed an expression vector harbouring a hygromycin B-resistant gene (hph) and an efficient green fluorescent protein (egfp) gene. By applying Agrobacterium AGL-1-mediated genetic transformation technology, we conducted molecular tagging of T. asperellum and monitored the colonization dynamics of T. asperellum in soil. The results of tracking five independent transformants of T. asperellum indicated that its expansion rates ranged from 4·7 to 6·8 cm week-1 . After inoculation in soil, the quantities of T. asperellum could be maintained at over 10 × 104  CFU per gram soil in the first year. In the third year after inoculation, the quantities of T. asperellum in soil were still higher than 1 × 103  CFU per gram soil. In addition, molecularly tagged T. asperellum in soil in the second year (i.e. 12 months) after inoculation could still reach the biocontrol effect on cucumber Rhizoctonia rot by more than 74%. CONCLUSION: Trichoderma asperellum strain T4 is capable of effectively colonizing in soil and surviving for more than 1 year. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has provided the scientific basis for applying T. asperellum as the biocontrol fungus for prevention and control of plant diseases.


Assuntos
Agentes de Controle Biológico , Microbiologia do Solo , Trichoderma/crescimento & desenvolvimento , Trichoderma/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Agentes de Controle Biológico/farmacologia , Contagem de Colônia Microbiana , Cucumis sativus/microbiologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Rhizoctonia/efeitos dos fármacos , Trichoderma/metabolismo
3.
Microbiol Res ; 230: 126347, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31586859

RESUMO

Biocontrol has emerged in recent years as an alternative to pesticides. Given the importance of environmental preservation using biocontrol, in this study two antagonistic bacteria against phytopathogenic fungi were isolated and evaluated. These bacterial strains, identified as Paenibacillus polymyxa NMA1017 and Burkholderia cenocepacia CACua-24, inhibited (70 to 80%) the development of two phytopathogens of economic importance: the fungus Rhizoctonia solani RhCh-14, isolated from chili pepper, and the oomycete Pythium ultimum PyFr-14, isolated from tomato. The spectrum was not limited to the previous pathogens, but also to other phytopathogenic fungus, some bacteria and other oomycetes. Fungi-bacteria microcultures observed with optical and scanning electron microscopy revealed hyphae disintegration and pores formation. The antifungal activity was found also in the supernatant, suggesting a diffusible compound is present. Innocuous tests on tobacco leaves, blood agar, bean seed germination and in Galleria mellonella larvae showed that strain NMA1017 has the potential to be a biocontrol agent. Greenhouse experiments with bean plants inoculated with P. polymyxa exhibited the efficacy to inhibit the growth of R. solani and P. ultimum. Furthermore, P. polymyxa NMA1017 showed plant growth promotion activities, such as siderophore synthesis and nitrogen fixation which can contribute to the crop development.


Assuntos
Antifúngicos/farmacologia , Burkholderia cenocepacia/química , Paenibacillus polymyxa/química , Controle Biológico de Vetores/métodos , Doenças das Plantas/microbiologia , Pythium/efeitos dos fármacos , Rhizoctonia/efeitos dos fármacos , Antifúngicos/metabolismo , Burkholderia cenocepacia/metabolismo , Paenibacillus polymyxa/metabolismo , Pythium/crescimento & desenvolvimento , Pythium/fisiologia , Rhizoctonia/crescimento & desenvolvimento , Rhizoctonia/fisiologia , Tabaco/crescimento & desenvolvimento , Tabaco/microbiologia
4.
J Agric Food Chem ; 67(47): 12987-13000, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31682431

RESUMO

The complex synthesis process, low utilization, and single function of fungicides have seriously hindered the development of fungicides in resistance to rice sheath blight. Here, an inexpensive and multifunctional Cu(II)-based water-dispersible humic acid (Cu-WH) fungicide with growth-promoting ability was developed with a simple method. A 3D molybdate carbon hierarchical nanosphere (MoO2-C-HN) catalyst was successfully synthesized using a green route and applied in a solid-phase activation of lignite to obtain water-dispersible humic acid. Cu(II)-based water-dispersible humic acid (Cu-WH) was then formed through a simple reaction of Cu(II) and the humic acid. The resultant Cu-WH showed strong antifungal performance against Rhizoctonia solani in laboratory incubation experiments. After being treated with Cu3-WH (0.1 mg L-1), the control efficiency of rice sheath blight at 1, 3, and 5 days after infection was 90.54%, 78.96%, and 66.31%, respectively. It also enhanced the water-holding capacity of the substrate and thus effectively improved the growth of rice seedlings. In comparison to commercial rice seedling substrate, the substrate treated with 8 wt % of Cu3-WH increased plant height, stem diameter, fresh weight, and chlorophyll content by 19.23%, 35.91%, 14.52%, and 42.85%, respectively. The newly developed Cu-WH thus can be used as a novel low-cost efficient fungicide and growth stimulator to treat rice sheath blight as well as to increase rice production.


Assuntos
Cobre/química , Cobre/farmacologia , Fungicidas Industriais/química , Fungicidas Industriais/farmacologia , Substâncias Húmicas/análise , Oryza/crescimento & desenvolvimento , Antifúngicos , Oryza/microbiologia , Doenças das Plantas/microbiologia , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/crescimento & desenvolvimento
5.
J Agric Food Chem ; 67(47): 13185-13194, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31697490

RESUMO

In searching for novel fungicidal leads, the novel bioactive succinate dehydrogenase inhibitor (SDHI) derivatives were designed and synthesized by the inversion of carbonyl and amide groups. Bioassay indicated that compound 5i stood out with a broad spectrum of in vitro activity against five fungi. Its EC50 value (0.73 µg/mL) was comparable to that of boscalid (EC50 of 0.51 µg/mL) and fluxapyroxad (EC50 of 0.19 µg/mL) against Sclerotinia sclerotiorum. For Rhizoctonia cerealis, 5i and 5p with EC50 values of 4.61 and 6.48 µg/mL, respectively, showed significantly higher activity than fluxapyroxad with the EC50 value of 16.99 µg/mL. In vivo fungicidal activity of 5i exhibited an excellent inhibitory rate (100%) against Puccinia sorghi at 50 µg/mL, while the positive control boscalid showed only a 70% inhibitory rate. Moreover, 5i showed promising fungicidal activity with a 60% inhibitory rate against Rhizoctonia solani at 1 µg/mL, which was better than that of boscalid (30%). Compound 5i possessed better in vivo efficacy against P. sorghi and R. solani than boscalid. Molecular docking showed that even the carbonyl oxygen atom of 5i was far from the pyrazole ring. It could also form hydrogen bonds toward the hydroxyl hydrogen and amino hydrogen of TYR58 and TRP173 on SDH, respectively, which consisted of the positive control fluxapyroxad. Fluorescence quenching analysis and SDH enzymatic inhibition studies also validated its mode of action. Our studies showed that 5i was worthy of further investigation as a promising fungicide candidate.


Assuntos
Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Proteínas Fúngicas/antagonistas & inibidores , Fungicidas Industriais/síntese química , Fungicidas Industriais/farmacologia , Succinato Desidrogenase/antagonistas & inibidores , Ascomicetos/química , Ascomicetos/efeitos dos fármacos , Ascomicetos/enzimologia , Inibidores Enzimáticos/química , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Fungicidas Industriais/química , Simulação de Acoplamento Molecular , Rhizoctonia/química , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/enzimologia , Relação Estrutura-Atividade , Succinato Desidrogenase/química , Succinato Desidrogenase/metabolismo
6.
World J Microbiol Biotechnol ; 35(9): 145, 2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31493267

RESUMO

The various diseases that occur during the growth of plants usually cause a significant reduction in production and quality of agricultural products. Actinomycetes, especially Streptomyces spp., become a valuable biological control resource due to their preponderant abilities to produce various secondary metabolites with novel structure and remarkable biological activity. The present work aimed to isolate an effective antagonistic actinomycete against various soilborne phytopathogenic fungi. By dual culture with Fusarium oxysporum f. sp. niveum, an antagonistic actinomycete named Streptomyces corchorusii stain AUH-1 was screened out from 26 soil samples. The in vitro bioassay results showed that S. corchorusii stain AUH-1 had a broad-spectrum antagonistic activity against a range of fungal plant pathogens, such as F. oxysporum f. sp. niveum, Phytophthora parasitica var. nicotianae, Rhizoctonia solani, P. capsica, Botryosphaeria dothidea, F. oxysporum f. sp. vasinfectum, Verticillium dahliae, and F. oxysporum f. sp. cucumerinum. According to the morphological observations in scanning electron microscopy (SEM) and fluorescence microscope (FM), it was found that the cell membranes of F. oxysporum f. sp. niveum were damaged when treated with the antifungal metabolite form S. corchorusii stain AUH-1. Meanwhile, the dropped ergosterol formation and increased malondialdehyde levels further confirmed that S. corchorusii strain AUH-1 exerted its antagonistic activity against F. oxysporum f. sp. niveum via damaging the structure and function of cell membranes. In conclusion, S. corchorusii strain AUH-1 showed a promising prospect for the development of biological agent, especially due to its broad-spectrum and effective antagonist on various soil-borne plant pathogens.


Assuntos
Antifúngicos/farmacologia , Doenças das Plantas/prevenção & controle , Microbiologia do Solo , Streptomyces/isolamento & purificação , Streptomyces/fisiologia , Antibiose , Antifúngicos/isolamento & purificação , Antifúngicos/metabolismo , Ascomicetos/efeitos dos fármacos , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Técnicas de Cocultura , Ergosterol/metabolismo , Fusarium/citologia , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Malondialdeído/metabolismo , Filogenia , Phytophthora/efeitos dos fármacos , Doenças das Plantas/microbiologia , Rhizoctonia/efeitos dos fármacos , Streptomyces/classificação , Verticillium/efeitos dos fármacos
7.
J Agric Food Chem ; 67(38): 10782-10790, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31490683

RESUMO

Systematic investigation of cyproconazole, including absolute stereochemistry, fungicidal activity, quantification in two matrixes, and stereoselective degradation in cucumber, are conducted in this study. By virtue of vibrational circular dichroism (VCD) spectroscopy, absolute configurations of four stereoisomers were identified to be (2R,3R)-(+)-, (2R,3S)-(+)-, (2S,3S)-(-)-, and (2S,3R)-(-)-cyproconazoles. Then four stereoisomers exhibited stereoselective fungicidal activities against Fusarium graminearum Schw and Magnaporthe oryzae, and the order of fungicidal activity was (2S,3S)-(-)-stereoisomer > the stereoisomer mixture > (2S,3R)-(-)-stereoisomer > (2R,3R)-(+)-stereoisomer > (2R,3S)-(+)-stereoisomer. Moreover, chiral liquid chromatography-tandem mass spectrometry was used to identify and quantify cyproconazole stereoisomers in soil and cucumber matrixes. Good linearity (R2 ≥ 0.99) and recoveries (86.79-92.47%, RSD ≤ 3.94%) for them were achieved, individually. Furthermore, stereoselective degradation of four cyproconazole stereoisomers was observed in cucumber and the order of degradation rate was (2R,3R)-(+)-cyproconazole > (2S,3S)-(-)-cyproconazole > (2R,3S)-(+)-cyproconazole > (2S,3R)-(-)-cyproconazole. We envision that such systematic assessments of chiral fungicides at an enantiomeric level would provide valuable information in future studies involving enantioselective physiological, metabolic, and toxicological activities.


Assuntos
Fungicidas Industriais/química , Triazóis/química , Alternaria/efeitos dos fármacos , Alternaria/crescimento & desenvolvimento , Cromatografia Líquida de Alta Pressão , Cucumis sativus/química , Contaminação de Alimentos/análise , Fungicidas Industriais/farmacologia , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/crescimento & desenvolvimento , Poluentes do Solo/química , Poluentes do Solo/farmacologia , Estereoisomerismo , Espectrometria de Massas em Tandem , Triazóis/farmacologia
8.
J Agric Food Chem ; 67(41): 11354-11363, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31532666

RESUMO

A series of dehydrozingerone derivatives were synthesized, and their fungicidal activities and action mechanism against Colletotrichum musae were evaluated. The bioassay result showed that most compounds exhibited excellent fungicidal activity in vitro at 50 µg mL-1. Compounds 13, 16, 18, 19, and 27 exhibited broad-spectrum fungicidal activity; especially, compounds 19 and 27 were found to have more potent fungicidal activity than azoxystrobin. The EC50 values of compounds 19 and 27 against Rhizoctonia solani were 0.943 and 0.161 µg mL-1 respectively. Moreover, compound 27 exhibited significant in vitro bactericidal activity against Xanthomonas oryzae pv. oryzae, with an EC50 value of 11.386 µg mL-1, and its curative effect (49.64%) and protection effect (51.74%) on rice bacterial blight disease was equivalent to that of zhongshengmycin (42.90%, 40.80% respectively). Compound 27 could also effectively control gray mold (87.10%, 200 µg mL-1) and rice sheath blight (100%, 200 µg mL-1; 82.89%, 100 µg mL-1) in vivo. Preliminary action mechanism study showed that compound 27 mainly acted on the cell membrane and significantly inhibited ergosterol biosynthesis in Colletotrichum musae.


Assuntos
Ergosterol/antagonistas & inibidores , Fungicidas Industriais/síntese química , Fungicidas Industriais/farmacologia , Estirenos/síntese química , Estirenos/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Colletotrichum/efeitos dos fármacos , Colletotrichum/metabolismo , Ergosterol/biossíntese , Fungicidas Industriais/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Oryza/microbiologia , Doenças das Plantas/microbiologia , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/metabolismo , Relação Estrutura-Atividade , Estirenos/química , Xanthomonas/efeitos dos fármacos , Xanthomonas/metabolismo
9.
World J Microbiol Biotechnol ; 35(8): 128, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31375920

RESUMO

Large patch disease, caused by Rhizoctonia solani AG2-2, is the most devastating disease in Zoysiagrass (Zoysia japonica). Current large patch disease control strategies rely primarily upon the use of chemical pesticides. Streptomyces sp. S8 is known to possess exceptional antagonistic properties that could potentially suppress the large patch pathogen found at turfgrass plantations. This study aims to demonstrate the feasibility of using the strain as a biological control mechanism. Sequencing of the S8 strain genome revealed a valinomycin biosynthesis gene cluster. This cluster is composed of the vlm1 and vlm2 genes, which are known to produce antifungal compounds. In order to verify this finding for the large patch pathogen, a valinomycin biosynthesis knockout mutant was created via the CRISPR/Cas9 system. The mutant lost antifungal activity against the large patch pathogen. Consequently, it is anticipated that eco-friendly microbial preparations derived from the S8 strain can be utilized to biologically control large patch disease.


Assuntos
Antifúngicos/metabolismo , Antifúngicos/farmacologia , Rhizoctonia/efeitos dos fármacos , Streptomyces/metabolismo , Valinomicina/metabolismo , Valinomicina/farmacologia , Vias Biossintéticas/genética , Técnicas de Inativação de Genes , Genoma Bacteriano , Família Multigênica , Controle Biológico de Vetores/métodos , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Poaceae/microbiologia , Rhizoctonia/crescimento & desenvolvimento , Análise de Sequência de DNA , Streptomyces/genética
10.
Genes (Basel) ; 10(8)2019 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-31405015

RESUMO

The genus Pseudomonas comprises many known plant-associated microbes with plant growth promotion and disease suppression properties. Genome-based studies allow the prediction of the underlying mechanisms using genome mining tools and the analysis of the genes unique for a strain by implementing comparative genomics. Here, we provide the genome sequence of the strain Pseudomonas brassicacearum 3Re2-7, formerly known as P. trivialis and P. reactans, elucidate its revised taxonomic classification, experimentally verify the gene predictions by transcriptome sequencing, describe its genetic biocontrol potential and contextualize it to other known Pseudomonas biocontrol agents. The P. brassicacearum 3Re2-7 genome comprises a circular chromosome with a size of 6,738,544 bp and a GC-content of 60.83%. 6267 genes were annotated, of which 6113 were shown to be transcribed in rich medium and/or in the presence of Rhizoctonia solani. Genome mining identified genes related to biocontrol traits such as secondary metabolite and siderophore biosynthesis, plant growth promotion, inorganic phosphate solubilization, biosynthesis of lipo- and exopolysaccharides, exoproteases, volatiles and detoxification. Core genome analysis revealed, that the 3Re2-7 genome exhibits a high collinearity with the representative genome for the species, P. brassicacearum subsp. brassicacearum NFM421. Comparative genomics allowed the identification of 105 specific genes and revealed gene clusters that might encode specialized biocontrol mechanisms of strain 3Re2-7. Moreover, we captured the transcriptome of P. brassicacearum 3Re2-7, confirming the transcription of the predicted biocontrol-related genes. The gene clusters coding for 2,4-diacetylphloroglucinol (phlABCDEFGH) and hydrogen cyanide (hcnABC) were shown to be highly transcribed. Further genes predicted to encode putative alginate production enzymes, a pyrroloquinoline quinone precursor peptide PqqA and a matrixin family metalloprotease were also found to be highly transcribed. With this study, we provide a basis to further characterize the mechanisms for biocontrol in Pseudomonas species, towards a sustainable and safe application of P. brassicacearum biocontrol agents.


Assuntos
Antifúngicos/metabolismo , Agentes de Controle Biológico/metabolismo , Genes Bacterianos , Pseudomonas/genética , Transcriptoma , Cianeto de Hidrogênio/metabolismo , Floroglucinol/análogos & derivados , Floroglucinol/metabolismo , Pseudomonas/metabolismo , Rhizoctonia/efeitos dos fármacos
11.
Pestic Biochem Physiol ; 158: 175-184, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378354

RESUMO

Succinate dehydrogenase (SDH), an essential component of cellular respiratory chain and tricarboxylic acid (or Krebs) cycle, has been identified as one of the most significant targets for pharmaceutical and agrochemical. Herein, with the aim of discovery of new antifungal lead structures, a class of novel N-(4-fluoro-2-(phenylamino)phenyl)-pyrazole-4-carboxamides were designed, synthesized and evaluated for their biological activities. They were bioassayed against seven phytopathogenic fungi, Rhizoctonia solani, Phytophthora infestans, Fusarium oxysporum f. sp. vasinfectum, Botryosphaeria dothidea, Gibberella zeae, Alternaria alternate and Fusarium oxysporum f. sp. niveum. The results indicated that most of the compounds displayed good antifungal activities, especially against R. solani. Among them, compounds 7 and 12 exhibited higher antifungal activities against R. solani in vitro with EC50 value of 0.034 mg/L and 0.021 mg/L, being superior to the commercially available fungicide bixafen (EC50 = 0.043 mg/L). Pot tests against R. solani showed that in vivo EC50 values of compounds 7 (2.694 mg/L) and 12 (2.331 mg/L) were higher than that of bixafen (3.724 mg/L). In addition, inhibitory activity of compound 12 against SDH indicated compound 12 (IC50 = 1.836 mg/L) showed good inhibitory activity against SDH, being close to bixafen's inhibitory activity (IC50 = 1.222 mg/L). And, molecular modeling of the SDH-compound 12 complex suggested that compound 12 could strongly bind to and interact with the binding site of the SDH. The results of the present work showed that N-(4-fluoro-2-(phenylamino)phenyl)-pyrazole-4-carboxamides were a new fungicides for discovery of SDH inhibitors and worth further study.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Succinato Desidrogenase/metabolismo , Alternaria/efeitos dos fármacos , Alternaria/enzimologia , Ascomicetos/efeitos dos fármacos , Ascomicetos/enzimologia , Fusarium/efeitos dos fármacos , Fusarium/enzimologia , Phytophthora infestans/efeitos dos fármacos , Phytophthora infestans/enzimologia , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/enzimologia , Relação Estrutura-Atividade
12.
J Environ Sci Health B ; 54(10): 810-816, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31264918

RESUMO

Pesticides are biological or chemical substances used to manage pests and diseases. Encapsulation of pesticides in biodegradable carriers creates a slow-release system that can improve water dispersibility and prolong residual activity. We prepared two kinds of poly (lactic-co-glycolic acid)(PLGA) nanoparticles (NPs) with polyvinyl alcohol (PVA) and sodium dodecyl sulfate (SDS) surfactants. These were used to encapsulate the fungicide fluazinam (Flu) against Rhizoctonia solani using the Shirasu Porous Glass (SPG) membrane emulsification method. Both nanoparticles had uniform spherical shapes with average diameters of 314.13 nm (SDS) and 612.80 nm (PVA). The slow-release microspheres had excellent sustained-release properties, resistance to UV degradation, storage stability, leaf surface coverage and antifungal efficacy compared to the commercial formulation.


Assuntos
Aminopiridinas/farmacocinética , Fungicidas Industriais/farmacocinética , Nanopartículas/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Aminopiridinas/farmacologia , Fungicidas Industriais/farmacologia , Microesferas , Tamanho da Partícula , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/metabolismo , Álcool de Polivinil/química , Porosidade , Rhizoctonia/efeitos dos fármacos , Dodecilsulfato de Sódio/química , Espectrofotometria Ultravioleta , Tensoativos/química
13.
Pestic Biochem Physiol ; 157: 230-236, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31153473

RESUMO

Zirconium oxide nanoparticles (ZrONPs) were synthesized and evaluated for their ability to induce root rot resistance in cucumber and direct antifungal activity against Rhizoctonia solani. Resistance induction was investigated using real-time polymerase chain reaction (RT-PCR) and the effect of ZrONPs on the growth of cucumber plants was investigated. The results showed that ZrONPs at a concentration level of 100 µg/L significantly inhibited the growth of Rhizoctonia solani (86.6%) relative to untreated control under laboratory conditions. Cucumber plants treated with ZrONPs showed reduction in the severity of root rot disease under greenhouse (34-46%) and field conditions (52-56%) compared with non-treated control plants. Cucumber plants treated with ZrONPs expressed regulatory and defense genes involved in the salicylic acid (SA) and jasmonic acid (JA)/ethylene (ET) signaling pathways with 7-8 folds higher than the control. Treatment of cucumber with ZrONPs and carboxin + thiram significantly improved cucumber growth and yield characters. Therefore, using ZrONPs could be a new strategy to control this pathogen and considered the first report.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Cucumis sativus/microbiologia , Nanopartículas/química , Rhizoctonia/efeitos dos fármacos , Zircônio/química
14.
Appl Microbiol Biotechnol ; 103(13): 5367-5377, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31053917

RESUMO

The bacterium, Bacillus amyloliquefaciens Pc3, was previously isolated from Antarctic seawater and has been found to show antagonistic activity against the fungus, Rhizoctonia solani ACCC 36316, which causes a severe disease known as Sclerotinia sclerotiorum in rapeseed plants. Bacillus lipopeptides had been widely used as biocontrol agents for plant diseases. In this study, we isolated 11 lipopeptide compounds from B. amyloliquefaciens Pc3 culture broth via reversed-phase high-performance liquid chromatography (RP-HPLC) and used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to identify these as iturin A (C14, C15, C16, C17), fengycin B (C14, C15, C16, C17), and surfactin (C14, C15, C16). We further found that the addition of exogenous alkanoic acids, including myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, octadecanoic acid, and nonadecanoic acid, to the bacterial growth media could promote lipopeptide production and enhance the antifungal activities of crude lipopeptide extracts from B. amyloliquefaciens Pc3. In addition, the transcriptional levels of three lipopeptide synthesis genes, ituD, fenA, and srfA-A, and two fatty acid metabolism-related genes, FabI, which encodes enoyl-ACP reductase, and FadB, which encodes enoyl-CoA hydratase, were found to be upregulated in cells grown with exogenous alkanoic acids. Among the six alkanoic acids tested, those with odd carbon chain lengths had a greater effect on lipopeptide production, antifungal activity, and target gene upregulation than those with even carbon chain lengths. These results provide a practical approach for the efficient production of lipopeptides in Bacillus amyloliquefaciens Pc3.


Assuntos
Antibiose , Antifúngicos/farmacologia , Bacillus amyloliquefaciens/efeitos dos fármacos , Bacillus amyloliquefaciens/metabolismo , Ácidos Carboxílicos/farmacologia , Lipopeptídeos/biossíntese , Bacillus amyloliquefaciens/genética , Ácidos Graxos/farmacologia , Lipopeptídeos/isolamento & purificação , Ácido Mirístico/farmacologia , Peptídeos Cíclicos/isolamento & purificação , Rhizoctonia/efeitos dos fármacos
15.
Chem Biodivers ; 16(7): e1900118, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31106521

RESUMO

In continuation of our previous research on the development of novel pyrazole-4-carboxamide with potential antifungal activity, compound SCU2028, namely N-[2-[(3-chlorophenyl)amino]phenyl]-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide, was synthesized by new method, structurally characterized by IR, HR-ESI-MS, 1 H- and 13 C-NMR spectra and further identified by single-crystal X-ray diffraction. In pot tests, compound SCU2028 showed good in vivo antifungal activity against Rhizoctonia solani (R. solani) and IC50 value of it was 7.48 mg L-1 . In field trials, control efficacy of compound SCU2028 at 200 g.a.i. ha-1 was 42.30 % on the 7th day after the first spraying and 68.10 % on the 14th day after the second spraying, only slightly lower than that of thifluzamide (57.20 % and 71.40 %, respectively). Further in vitro inhibitory activity showed inhibitory ability of compound SCU2028 was 45-fold higher than that of bixafen and molecular docking of compound SCU2028 to SDH predicted its binding orientation in the active site of the target protein SDH. These results suggested that compound SCU2028 was a potential fungicide for control of rice sheath blight.


Assuntos
Antifúngicos/farmacologia , Simulação de Acoplamento Molecular , Pirazóis/farmacologia , Rhizoctonia/efeitos dos fármacos , Antifúngicos/síntese química , Antifúngicos/química , Cristalografia por Raios X , Testes de Sensibilidade Microbiana , Estrutura Molecular , Pirazóis/síntese química , Pirazóis/química
16.
J Agric Food Chem ; 67(17): 5008-5016, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30977370

RESUMO

A series of novel N-(2-(phenylamino)-4-fluorophenyl)-pyrazole-4-carboxamides 1-15 and aromatic carboxamides with a diphenylamine scaffold 16-29 were designed, synthesized, and evaluated for their antifungal activities. In vitro experiments showed that compound 6 (EC50 = 0.03 mg/L) was superior to bixafen (EC50 = 0.04 mg/L) against Rhizoctoinia solani and compound 6 (IC50 = 1.41 mg/L) was close to bixafen (IC50 = 1.22 mg/L) against succinate dehydrogenase from R. solani. Additionally, in vivo pot experiments showed that compound 6 (EC50 = 1.93 mg/L) was better than bixafen (EC50 = 3.72 mg/L) and close to thifluzamide (EC50 = 1.83 mg/L) against R. solani. In vivo field trials showed that compound 6 at 200 g ai ha-1 had 64.10% control efficacy against rice sheath blight after 21 days with two sprayings, close to thifluzamide (71.40%). Furthermore, molecular docking showed that compound 6 anchors in the binding site of SDH.


Assuntos
Fungicidas Industriais/síntese química , Fungicidas Industriais/farmacologia , Difenilamina/química , Desenho de Drogas , Fungicidas Industriais/química , Simulação de Acoplamento Molecular , Estrutura Molecular , Oryza/microbiologia , Doenças das Plantas/microbiologia , Rhizoctonia/efeitos dos fármacos
17.
Bull Environ Contam Toxicol ; 102(6): 880-886, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30923837

RESUMO

Fungicidal effect of 2-amino-4-nitrophenol and its derivates, prepared by replacing the hydrogen atom in its amino group by different organic radicals was studied. Evaluation of the biological activity of studied substances by сomputational chemistry methods was performed. Toxicity of 2-amino-4-nitrophenol and synthesized N-(2-hydroxy-5-nitrophenyl)formamide and N-(2-hydroxy-5-nitrophenyl)acetamide to six species of phytophatogen fungi were tested in the experiment. The results of the study demonstrate that replacement of the hydrogen atom in the amino group by a aldehyde group leads to an increase in fungicidal activity with respect to Rhizoctonia solani and Bipolaris sorokiniana. A replacement of the hydrogen atom by a ketone group increases the inhibitory effect on Sclerotinia sclerotiorum and Venturia inaequalis. The paper contains comparative data on the fungicide effect of commercial preparation for studied fungi also.


Assuntos
Ascomicetos/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Nitrofenóis/farmacologia , Rhizoctonia/efeitos dos fármacos , Acetamidas/química , Acetamidas/farmacologia , Formamidas/química , Formamidas/farmacologia , Fungicidas Industriais/química , Cetonas/química , Cetonas/farmacologia , Nitrofenóis/química , Relação Estrutura-Atividade
18.
Arch Microbiol ; 201(6): 787-794, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30863921

RESUMO

A novel antifungalmycin N2 (3-methyl-3,5-amino-4-vinyl-2-pyrone, C6H7O2N) was previously discovered from Streptomyces sp. N2, which exerted a broad-spectrum antagonistic activity against phytopathogenic fungi. To provide comprehensive insights into the antagonistic mechanisms and biocontrol efficacy of antifungalmycin N2, the present work investigated the physiological responses of Rhizoctonia solani under interaction with antifungalmycin N2. First, the mycelial growth of R. solani was significantly inhibited by antifungalmycin N2 during liquid shake-flask culture. Morphological observations showed that the morphogenesis of R. solani was influenced by antifungalmycin N2, in which the hyphae became severely shriveled and flattened, irregularly folded and branched. Additionally, an obvious accumulation of reactive oxygen species (ROS) was detected in R. solani hyphae, indicating oxidative stress induced by antifungalmycin N2. Further results showed that chitinase activity and its hydrolytic N-acetylglucosamine were significantly accelerated by antifungalmycin N2, demonstrating the cell wall of R. solani was damaged. Interestingly, the enzymatic antioxidant activities of R. solani were significantly induced in response to a relatively low concentration of antifungalmycin N2 (1.44-5.77 µg/mL). However, all antioxidant enzymes became highly inactive when the antifungalmycin N2 was increased to 11.53 µg/mL, suggesting that the enzymatic antioxidant system in R. solani was probably collapsed by the oxidative stress beyond its acceptance scope. In conclusion, antifungalmycin N2 exerted its antagonistic activity by inducing both cell wall degradation and oxidative stress in R. solani, thus leading to fungal morphogenesis and autolysis. Meanwhile, R. solani could induce and activate its antioxidant enzymes as a defence response to the oxidative stress caused by antifungalmycin N2.


Assuntos
Antifúngicos/farmacologia , Rhizoctonia/efeitos dos fármacos , Streptomyces/química , Antifúngicos/metabolismo , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Proteínas Fúngicas/metabolismo , Hifas/efeitos dos fármacos , Hifas/enzimologia , Hifas/crescimento & desenvolvimento , Hifas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Rhizoctonia/enzimologia , Rhizoctonia/crescimento & desenvolvimento , Rhizoctonia/metabolismo , Streptomyces/metabolismo
19.
Pest Manag Sci ; 75(10): 2765-2769, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30801938

RESUMO

BACKGROUND: Pueraria peduncularis belongs to the genus Pueraria DC, and has a wide range of medical and agricultural activities. Previous studies have shown that P. peduncularis extracts have broad bioactivities against phytopathogens. In this paper, we systematically studied the fungicidal activity of root methanol extracts and further isolated the active compounds. RESULTS: The root methanol extract inhibited the mycelial growth of the five tested phytopathogens to different degrees. Among these phytopathogens, the inhibitory effect was greatest against R. solani, with an EC50 value of 324.72 mg L-1 . Eight compounds were subsequently isolated and identified from P. peduncularis. Among them, puercarpan A and medicarpin showed strong fungicidal activity, with MIC values against Rhizoctonia solani of 1.6 and 6.25 mg L-1 , respectively. Puercarpan A is a new compound, and its structure was established as (6aR,6bS,11aR)-6b-hydroxy-3-methoxypterocarpan-10-ene-7-one. CONCLUSION: The P. peduncularis extracts exhibit high antimicrobial activity against R. solani and have great potential value of P. peduncularis as a fungicide. © 2019 Society of Chemical Industry.


Assuntos
Fungicidas Industriais/farmacologia , Raízes de Plantas/química , Pueraria/química , Rhizoctonia/efeitos dos fármacos
20.
Plant Mol Biol ; 100(1-2): 59-71, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30796712

RESUMO

KEY MESSAGE: RNAi mediated silencing of pectin degrading enzyme of R. solani gives a high level of resistance against sheath blight disease of rice. Rice sheath blight disease caused by Rhizoctonia solani Kuhn (telemorph; Thanatephorus cucumeris) is one of the most devastating fungal diseases which cause severe loss to rice grain production. In the absence of resistant cultivars, the disease is currently managed through fungicides which add to environmental pollution. To explore the potential of utilizing RNA interference (RNAi)-mediated resistance against sheath blight disease, we identified genes encoding proteins and enzymes involved in the RNAi pathway in this fungal pathogen. The RNAi target genes were deciphered by RNAseq analysis of a highly virulent strain of the R. solani grown in pectin medium. Additionally, pectin metabolism associated genes of R. solani were analyzed through transcriptome sequencing of infected rice tissues obtained from six diverse rice cultivars. One of the key candidate gene AG1IA_04727 encoding polygalacturonase (PG), which was observed to be significantly upregulated during infection, was targeted through RNAi to develop disease resistance. Stable expression of PG-RNAi construct in rice showed efficient silencing of AG1IA_04727 and suppression of sheath blight disease. This study highlights important information about the existence of RNAi machinery and key genes of R. solani which can be targeted through RNAi to develop pathogen-derived resistance, thus opening an alternative strategy for developing sheath blight-resistant rice cultivars.


Assuntos
Resistência à Doença/genética , Oryza/genética , Oryza/microbiologia , Pectinas/farmacologia , Doenças das Plantas/microbiologia , Interferência de RNA , Rhizoctonia/genética , Transcriptoma/genética , Progressão da Doença , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Doenças das Plantas/genética , Poligalacturonase/genética , Poligalacturonase/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Rhizoctonia/efeitos dos fármacos , Análise de Sequência de RNA , Transformação Genética
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