Fungicide Research Articles

Antibacterial Activity and Composition of the Fermentation Broth of Streptomyces Parvus 33

Background: Microorganisms represent a potentially valuable source of biologically significant compounds that should be explored for their potential agrochemical use. Objectives: The compounds ZM-1 and ZM-2 were isolated from the extract of the fermentation broth of Streptomyces parvus 33 by bioassay-guided fractionation. Methods: The compound ZM-1 was isolated in the form of a clear single crystal for the first time, and identified as holomycin via X-ray crystallography. The compound ZM-2 was characterized by IR, 1H-NMR, 13C-NMR, DEPT (90° and 135°), and MS analyses. Results: The compound ZM-1 showed a strong antibacterial activity against the tested bacteria, and its value of minimum inhibitory concentration (MIC) was greater than that of the positive control Ampicillin. The compound ZM-1 also exhibited significant antimicrobial activities against some plant pathogenic fungi. Nevertheless, ZM-2 showed no activities against the tested bacteria and plant pathogenic fungi. Conclusions: The compound ZM-1 was isolated in the form of a clear single crystal for the first time, and identified as holomycin via X-ray crystallography. Streptomyces parvus 33 is a newly discovered producer of holomycin. ZM-1 showed a strong antibacterial activity against the tested bacteria. Therefore, the compound ZM-1 is a valuable lead compound for the development of agricultural fungicides while acts against bacteria, as well.

Abundance, genetic diversity and sensitivity to demethylation inhibitor fungicides of Aspergillus fumigatus isolates from organic substrates with special emphasis on compost.

Aspergillus fumigatus is a widespread fungus that colonizes dead organic substrates but it can also cause fatal human diseases. Aspergilloses are treated with demethylation inhibitor (DMI) fungicides; however, resistant isolates appeared recently in the medical and also environmental area. The present study aims at molecular characterizing and quantifying A. fumigatus in major environmental habitats and determining its sensitivity to medical and agricultural DMI fungicides. A. fumigatus was isolated only rarely from soil and meadow/forest organic matter but high concentrations (103 to 107 cfu/g) were detected in substrates subjected to elevated temperatures, such as compost and silage. High genetic diversity of A. fumigatus from compost was found based on SSR markers, distinguishing among fungal isolates even when coming from the same substrate sample, while subclustering was observed based on mutations in cyp51A gene. Several cyp51A amino acid substitutions were found in 15 isolates, although all isolates were fully sensitive to the tested DMI fungicides, with exception of one isolate in combination with one fungicide. This study suggests that the tested A. fumigatus isolates collected in Italy, Spain and Hungary from the fungus' major living habitats (compost) and commercial growing substrates are not potential carriers for DMI resistance in the environment. © 2017 Society of Chemical Industry.

Purification and identification of a novel peptide derived from by-products fermentation of spiny head croaker ( Collichthys lucidus ) with antifungal effects on phytopathogens

In our previous study, spiny head croaker (Collichthys lucidus) by-products fermentation (SBF) products demonstrated plant growth promoting effects. In this study, the antimicrobial activities of SBF against plant pathogenic fungi and food-borne bacteria were evaluated. An active antifungal fraction SBF-3-1 was isolated from SBF using size exclusion chromatography and high performance liquid chromatography. Seven short peptides, i.e., LDEGW, DSFDFK, LDGW, FPDL, YNLDFK, FDGF and LDFE, plus one 22 residues peptide TFNTPAMYVAIQAVLSLYASGR were identified in SBF-3-1 by liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI-Q-TOF-MS/MS). The peptide TFNTPAMYVAIQAVLSLYASGR (named as SBF-3-1p), a potential antimicrobial peptide predicted by the antimicrobial peptide database (APD, http://aps.unmc.edu/AP/main.php), was further characterized. The prediction showed that the generation of SBF-3-1p could be associated with the action of trypsin and glutamyl endopeptidase, two proteases with specific cleavage sites on the carboxyl side of arginine (R) and lysine (K), and on the carboxyl side of Glu (E), respectively. According to the structural modeling, SBF-3-1p contained one α-helix and two loop regions. The synthesized SBF-3-1p exhibited strong activity against plant pathogenic fungus Pestalotiopsis sp. Therefore, SBF should be a good source of antifungal peptide, and could be used as natural fungicides in agriculture.

Synthesis, fungicidal evaluation and 3D-QSAR studies of novel 1,3,4-thiadiazole xylofuranose derivatives.

1,3,4-Thiadiazole and sugar-derived molecules have proven to be promising agrochemicals with growth promoting, insecticidal and fungicidal activities. In the research field of agricultural fungicide, applying union of active group we synthesized a new set of 1,3,4-thiadiazole xylofuranose derivatives and all of the compounds were characterized by 1H NMR and HRMS. In precise toxicity measurement, some of compounds exhibited more potent fungicidal activities than the most widely used commercial fungicide Chlorothalonil, promoting further research and development. Based on our experimental data, 3D-QSAR (three-dimensional quantitative structure-activity relationship) was established and investigated using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques, helping to better understand the structural requirements of lead compounds with high fungicidal activity and environmental compatibility.

Suppressing black anther symptoms in orchid inflorescences by fungicides

Suppressing black anther symptoms in orchid inflorescences by fungicides

Peer review of the pesticide risk assessment of the active substance Clonostachysrosea strain J1446 (approved in Regulation (EU) No540/2011 as Gliocladiumcatenulatum strain J1446).

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Hungary, and co‐rapporteur Member State, the Netherlands, for the pesticide active substance Clonostachys rosea strain J1446, currently approved as Gliocladium catenulatum strain J1446, are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of Clonostachys rosea strain J1446 as a fungicide in agriculture and horticulture. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Generational comparisons (F1 versus F3) of vinclozolin induced epigenetic transgenerational inheritance of sperm differential DNA methylation regions (epimutations) using MeDIP-Seq.

Environmentally induced epigenetic transgenerational inheritance of disease and phenotypic variation has been shown to involve DNA methylation alterations in the germline (e.g. sperm). These differential DNA methylation regions (DMRs) are termed epimutations and in part transmit the transgenerational phenotypes. The agricultural fungicide vinclozolin exposure of a gestating female rat has previously been shown to promote transgenerational disease and epimutations in F3 generation (great-grand-offspring) animals. The current study was designed to investigate the actions of direct fetal exposure on the F1 generation rat sperm DMRs compared to the F3 transgenerational sperm DMRs. A protocol involving methylated DNA immunoprecipitation (MeDIP) followed by next-generation sequencing (Seq) was used in the current study. Bioinformatics analysis of the MeDIP-Seq data was developed and several different variations in the bioinformatic analysis were evaluated. Observations indicate needs to be considered. Interestingly, the F1 generation DMRs were found to be fewer in number and for the most part distinct from the F3 generation epimutations. Observations suggest the direct exposure induced F1 generation sperm DMRs appear to promote in subsequent generations alterations in the germ cell developmental programming that leads to the distinct epimutations in the F3 generation. This may help explain the differences in disease and phenotypes between the direct exposure F1 generation and transgenerational F3 generation. Observations demonstrate a distinction between the direct exposure versus transgenerational epigenetic programming induced by environmental exposures and provide insights into the molecular mechanisms involved in the epigenetic transgenerational inheritance phenomenon.

Fungicide Aplication From Turminic Extract (Curcuma domestica Val.) to Control of Fusarium on Tomato

Fungicide Aplication From Turminic Extract (Curcuma domestica Val.) to Control of Fusarium on Tomato

Benzimidazole계 살균제에 대한 배 검은별무늬병균 Venturia nashicola 의 저항성과 β-Tubulin 유전자 돌연변이와의 관계

Benzimidazole계 살균제에 대한 배 검은별무늬병균 Venturia nashicola 의 저항성과 β-Tubulin 유전자 돌연변이와의 관계

Azole Resistance in Aspergillus fumigatus: A Consequence of Antifungal Use in Agriculture?

Agricultural industry uses pesticides to optimize food production for the growing human population. A major issue for crops is fungal phytopathogens, which are treated mainly with azole fungicides. Azoles are also the main medical treatment in the management of Aspergillus diseases caused by ubiquitous fungi, such as Aspergillus fumigatus. However, epidemiological research demonstrated an increasing prevalence of azole-resistant strains in A. fumigatus. The main resistance mechanism is a combination of alterations in the gene cyp51A (TR34/L98H). Surprisingly, this mutation is not only found in patients receiving long-term azole therapy for chronic aspergillosis but also in azole naïve patients. This suggests an environmental route of resistance through the exposure of azole fungicides in agriculture. In this review, we report data from several studies that strongly suggest that agricultural azoles are responsible for medical treatment failure in azole-naïve patients in clinical settings.

Controle químico da mela-das-sementes e do carvão em cultivares de Brachiaria brizantha

RESUMO O Brasil é o maior produtor, consumidor e exportador mundial de sementes de espécies forrageiras tropicais. Contudo, a produção tem sido ameaçada pela presença de fungos e fitonematoides, os quais podem reduzir a produtividade e/ou a qualidade das sementes produzidas, além de constituírem barreiras sanitárias para vários países importadores dessas sementes. Em Brachiaria spp., as principais doenças são a mela-das-sementes e o carvão, causadas, respectivamente, pelos fungos Claviceps maximensis e Ustilago operta. Apesar da grande demanda pelo setor produtivo, poucos são os estudos relacionados a estratégias de controle das doenças. Assim, realizou-se este trabalho objetivando-se avaliar a eficiência de fungicidas no controle das referidas doenças. Implantaram-se quatro experimentos, sendo dois na Embrapa Gado de Corte, em Campo Grande-MS, e dois em Paraíso das Águas-MS. Foram utilizadas as cultivares BRS Piatã e Xaraés, ambas pertencentes à Brachiaria brizantha. Foram avaliados os efeitos de vários fungicidas (g ia/ha), os quais foram aplicados em três épocas para Campo Grande: plantas com 10% de antese, 20 e 40 dias após a primeira aplicação. Em Paraíso das Águas, os fungicidas foram aplicados uma única vez, nas plantas com 10% de antese. Na cultivar BRS Piatã, para Campo Grande, os melhores resultados obtidos para o controle da mela-das-sementes foram com os tratamentos T7 (trifloxistrobina + ciproconazole (150,0 + 64,0)) e T11 (primeira aplicação: piraclostrobina (97,5) + epoxiconazole (60,0), segunda aplicação: tebuconazole (120,0), terceira aplicação: piraclostrobina (97,5) + epoxiconazole (60,0)). Na cultivar Xaraés, a doença foi menos expressiva nos tratamentos T4 (piraclostrobina (175,0)), T6 (azoxistrobina + ciproconazole (80,0 + 32,0)), T9 (primeira aplicação: piraclostrobina (175,0); segunda e terceira aplicações: piraclostrobina + epoxiconazole (99,75 + 37,5)) e T11 (primeira aplicação: piraclostrobina (97,5) + epoxiconazole (60,0), segunda aplicação: tebuconazole (120,0), terceira aplicação: piraclostrobina + epoxiconazole (97,5 + 60,0)). Não houve ocorrência de carvão para ambas as cultivares em Campo Grande. Para BRS Piatã, no experimento de Paraíso das Águas-MS, apesar da intensidade de mela-das-sementes e de carvão não terem sido expressivas, no tratamento T4 (piraclostrobina (175,0) a produtividade de sementes puras foi 69,6% maior que a testemunha, produzindo 456,78 kg/ha, demonstrando alta relação benefício/custo com o referido tratamento. Tal resultado em T4 pode ter sido expressão de efeitos fisiológicos proporcionados pela piraclostrobina. A aplicação de fungicidas na parte aérea das plantas de BRS Xaraés de Brachiaria brizantha em Campo Grande, onde houve alta incidência dos fungos Alternaria spp., Bipolaris spp., Curvularia spp., Fusarium spp. e Phoma spp. nas sementes, revelou o efeito benéfico do tratamento, sobretudo do T7 (trifloxistrobina + ciproconazole (150,0 + 64,0)), o qual reduziu significativamente a ocorrência de Bipolaris spp., Fusarium spp. e Phoma spp. Em Paraíso das Águas, onde a incidência dos referidos patógenos foi menor, os resultados não foram conclusivos.

Sorption of thiabendazole in sub-tropical Brazilian soils.

Thiabendazole (TBZ) is an ionizable anthelmintic agent that belongs to the class of benzimidazoles. It is widely used in veterinary medicine and as a fungicide in agriculture. Sorption and desorption are important processes influencing transport, transformation, and bioavailability of xenobiotic compounds in soils; data related to sorption capacity are therefore needed for environmental risk assessments. The aim of this work was to assess the sorption potential of TBZ in four Brazilians soils (sandy, sandy-clay, and clay soils), using batch equilibrium experiments at three pH ranges (2.3-3.0, 3.8-4.2, and 5.5-5.7). The Freundlich sorption coefficient (K F) ranged from 9.0 to 58μg1-1/n (mL) 1/n g-1, with higher values generally observed at the lower pH ranges (2.3-3.0 and 3.8-4.2) and for clay soils. The highest organic carbon-normalized sorption coefficients (KOC) obtained at pH3.8-5.7 (around the natural pH range of 4.1-5.0) for both clay soils and sandy-clay soil were 3255 and 2015mLg-1, respectively. The highest correlations K F vs SOM (r=0.70) and K F vs clay content (r=0.91) were observed at pH3.8-4.2. Our results suggest that TBZ sorption/desorption is strongly pH dependent and that its mobility could be higher in the studied soils than previously reported in soils from temperate regions.

Quitosano: un polisacárido antimicrobiano versátil para frutas y hortalizas en poscosecha – una revisión

Esta documentado que el quitosano controla numerosas enfermedades poscosecha en diversos productos horticolas. Hasta la fecha, y considerando un enfoque multifacetico, se ha evaluado la integracion del quitosano con otras alternativas (fisicas y quimicas, entre otras) para reducir la incidencia de enfermedades durante el almacenamiento de frutas y hortalizas. Actualmente, el control de microorganismos patogenos en poscosecha con nanomateriales de quitosano sigue siendo una tecnologia emergente. En general, los resultados indican que la combinacion de quitosano con otros metodos de control prolonga la vida de almacenamiento de diversos productos horticolas importantes; en gran parte, debido a la disminucion de la incidencia de microorganismos. El objetivo de este articulo fue recopilar, analizar y resumir informacion relevante acerca del uso de quitosano con otros metodos de conservacion (incluyendo calor, radiacion ultra violeta [UV], envasado en atmosfera modificada [MAP], derivados vegetales, acidos inorganicos, sales, microorganismos antagonistas, fungicidas y otros recubrimientos) sobre su actividad antimicrobiana en frutas y hortalizas. Adicionalmente, se revisaron avances recientes sobre nanomateriales basados en quitosano. A pesar de que se han demostrados los efectos positivos del quitosano, aun falta realizar evaluaciones a gran escala para su integracion en practicas poscosecha

Synthesis and Characterization of 1-(1-chlorocyclopropyl)-2-(1,2,4-triazol-1-yl)ethan-1-one

Abstract A simple and efficient method to prepare 1-(1-chlorocyclopropyl)-2-(1,2,4-triazol-1-yl)ethan-1-one via nucleophilic substitution of 2-chloro-1-(1-chlorocyclopropyl)ethanone and 1,2,4-triazole is described. The title compound is the key intermediate required for the synthesis of prothioconazole, a promising agricultural fungicide. By exploring changes in the reaction time, temperature, ratio of starting reagents, acid binding agent, and the nature of phase transfer catalyst, the reaction conditions could be optimized to afford the desired N-alkylated material in near-quantitative yield. The ultimate yield of the product after recrystallization was 93%, with a purity of 99% based on its characterization by Gas Chromatography-Mass Spectrometer (GC-MS), Fourier Transform infrared spectroscopy (IR), Proton Magnetic Resonance (1H NMR), and Carbon-13 Nuclear Magnetic Resonance (13C NMR). The synthetic process is suitable for industrial application, with the advantages of high yield and facile preparation under mild operating conditions.

Binding of carbendazim to bovine serum albumin: Insights from experimental and molecular modeling studies

Carbendazim (CBZ) is a widely used benzimidazole fungicide in agriculture to control a wide range of fruit and vegetable pathogens, which may lead to potential health hazards. To evaluate the potential toxicity of CBZ, the binding mechanism of bovine serum albumin (BSA) with CBZ was investigated by the fluorescence quenching technology, UV absorbance spectra, circular dichroism (CD), and molecular modeling. The fluorescence titration and UV absorbance spectra revealed that the fluorescence quenching mechanism of BSA by CBZ was a combined quenching process. In addition, the studies of CD spectra suggested that the binding of CBZ to BSA changed the secondary structure of protein. Furthermore, the thermodynamic functions of enthalpy change (ΔH0) and entropy change (ΔS0) for the reaction were calculated to be 24.87 kJ mol−1 and 162.95 J mol−1 K−1 according to Van't Hoff equation. These data suggested that hydrophobic interaction play a major role in the binding of CBZ to BSA, which was in good agreement with the result of molecular modeling study.

Colorimetric Assay for 4-Phenylthiosemicarbazide Detection in Environmental Samples Based on Prussian Blue Nanoparticles Formation Ion

In this research, a fast colorimetric method for the detection of 4-phenylthiosemicarbazid (4-PTSC) in environmental samples, is reported for the first time. Semicarbazide compounds have been used as pesticides or fungicides in agriculture and for chemical synthesis in industrial processes. With this method, one or the total amount of Semicarbazide in real samples can be detected within 6-7 min. For this purpose, 4-PTSC was determined and can be used as a representative of the Semicarbazide family. The assay principle is based on the oxidation of 4-phenylthiosemicarbazid (as reducing agent) with Ferric ions in the presence of ferricyanide ion and triton X-100 as a stabilizer, as well as the formation of Prussian Blue NanoParticles (PBNPs). These nanoparticles exhibit a strong UV-Vis extinction band at 700 nm with high absorption coefficient (3.0× 104 M-1 cm-1 at 700 nm). A UV-Vis spectrophotometer is used to monitor changes in the absorption intensity of PBNPs. A change in the color of the solution can be easily observed by naked eyes, in the presence of sub-ppm levels of 4-PTSC, which is directly related to the 4-PTSC concentration. TEM images showed an average diameter of 30 nm. The effect of several reaction variables on the formation rate of PBNPs was studied. Beer's law was obeyed in the concentration range of 0.20-3.20 µg/mL. The detection limit was found to be 0.10 µg/mL. This method was successfully applied for the determination of 4-PTSC in different environmental samples. Interfering species with reducing properties are not commonly present in environmental samples. Hence, this optical assay is simple and has acceptable selectivity.

IMPACT OF ANTIOXIDANTS AND MICRONUTRIENTS AS FUNGICIDES ALTERNATIVES IN IMPROVEMENT OF ANTAGONISM OF TRICHODERMA spp. AGAINST SCLEROTINIA SCLEROTIORUM

S. sclerotiorum is a strong and resident soil pathogen with high resistance to synthetic fungicides. The biocontrol agent Trichoderma spp. alone provides moderate control of this fungus. In present study, potassium tartrate, ascorbic acid, folic acid, thiamine and micronutrients mixture were used to improve the number of spores, fresh and dry weights, crude extracts, volatile compounds, and secondary metabolites produced by four isolates of Trichoderma against pathogen. A onetime amendment of thiamine (0.1%) or micronutrients mixture improve the antagonism efficacy of most Trichoderma isolates showing complete prevention of pathogen growth and inhibition of sclerotia formation.

METALAXYL SENSITIVITY AND AGGRESSIVENESS OF

Leaf blight caused by Phytophthora colocasiae is the most devastating disease of taro (Colocasia esculenta). P. colocasiae isolates belonging to four morphogroups were assessed for their aggressiveness and reaction to the metalaxyl fungicide Ridomil Gold 60WP. Based on sporangia morphology and partial β tubulin sequence homology all fungal isolates associated with and recovered from infected leaves were identified as P. colocasiae. Significant differences (P< 0.05) were observed among the isolates based on the various parameters (incubation period, lesion size and sporangia produced) taken into consideration. Similarly, the various isolates reacted differently to the test fungicide. Eleven of the isolates were considered to be moderately resistant, whilst 69 (86.2%) were found to be susceptible to the fungicide. None of the tested isolates was metalaxyl-resistant. Results of the study showed differences in the organism causing taro leaf blight disease in Ghana based on their aggressiveness potentials as measured by the epidemiological components. Also the lack of an identified resistant isolate shows the potential of employing metalaxyl based fungicide in managing taro leaf blight caused by P. colocasiae.

EXPLOITATION OF PROMISING NATIVE STRAINS OF BACILLUS SUBTILIS WITH ANTAGONISTIC PROPERTIES AGAINST FUNGAL PATHOGENS AND THEIR PGPR CHARACTERISTIC

Fifteen Bacillus subtilis strains which produced antifungal substances against plant pathogens i.e. Fusarium oxysporum f. sp. melonis, Rhizoctonia solani (RRS1) and Rhizoctonia solani (PRS1) were characterized biochemically and screened in vitro for their plant growth promoting traits as indole acetic acid (IAA), siderophore and hydrogen cyanide (HCN) production, as well as their antagonistic activity. In dual culture assays B. subtilis strains implicated decreased growth of F. oxysporum f. sp. melonis (upto 85.5%) causing muskmelon wilt, R. solani (RRS1) (upto 73.7%) causing sheath blight of rice and R. solani (PRS1) (upto 82.5%) causing black scurf of potato. The production of indole acetic acid (IAA) by all rhizobacteria was investigated as important mechanism for plant growth stimulation. Maximum in vitro IAA values were producedby B. subtilis FDK-21L (7.0 µg/ml) by addition of Ltryptophan in the culture medium. B. subtilis FDK-21L presented high activity of siderophore production. Diameter of halo varied from 0.4 to 3.2 cm on CAS agar plates. FDK-21L showed significant reduction of muskmelon wilt incidence (65.7%), disease severity of sheath blight of rice (70.8%) and black scurf of potato (97.2%). As B. subtilis FDK-21L exhibited several traits beneficial to the host and showed promising results when applied as bioinoculant, it may be used to develop new, safer and effective formulation as an alternative to chemical fungicides.

Selection and Characterization of DNA Aptamers for Electrochemical Biosensing of Carbendazim.

This article reports a novel aptamer-based impedimetric detection of carbendazim, a commonly used benzimidazole fungicide in agriculture. High affinity and specificity DNA aptamers against carbendazim were successfully selected using systematic evolution of ligand by exponential enrichment (SELEX). The dissociation constants (Kds) of the selected DNA aptamers after 10 in vitro selection cycles were characterized using fluorescence-based assays showing values in the nanomolar range. The aptamer which showed the highest degree of affinity and conformation change was used to fabricate an electrochemical aptasensor via self-assembly of thiol-modified aptamer on gold electrodes. The aptasensor exploits the specific recognition of carbendazim by the aptamer immobilized on the gold surface which leads to conformational changes in the aptamer structure. This conformational change alters the access of a ferrocyanide/ferricyanide redox couple to the aptasensor surface. The aptasensor response is thus measured by following the increase in the electron transfer resistance of the redox couple using Faradaic electrochemical impedance spectroscopy. This method allowed a selective and sensitive label-free detection of carbendazim within a range of 10 pg/mL-10 ng/mL with a limit of detection of 8.2 pg/mL. The aptasensor did not show cross reactivity with other commonly used pesticides such as fenamiphos, isoproturon, atrazine, linuron, thiamethoxam, trifluralin, carbaryl, and methyl parathion. Moreover, the aptasensor has been applied in different spiked food matrixes showing high recovery percentages. We believe that the proposed aptasensor is a promising alternative to the currently used methods for carbendazim monitoring.