Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.212
Filtrar
1.
PLoS One ; 18(1): e0268385, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36656908

RESUMO

Downy mildew is caused by Plasmopara viticola, an obligate oomycete plant pathogen, a devasting disease of grapevine. To protect plants from the disease, complex III inhibitors are among the fungicides widely used. They specifically target the mitochondrial cytochrome b (cytb) of the pathogen to block cellular respiration mechanisms. In the French vineyard, P. viticola has developed resistance against a first group of these fungicides, the Quinone outside Inhibitors (QoI), with a single amino acid substitution G143A in its cytb mitochondrial sequence. The use of QoI was limited and another type of fungicide, the Quinone inside Inhibitors, targeting the same gene and highly effective against oomycetes, was used instead. Recently however, less sensitive P. viticola populations were detected after treatments with some inhibitors, in particular ametoctradin and cyazofamid. By isolating single-sporangia P. viticola strains resistant to these fungicides, we characterized new variants in the cytb sequences associated with cyazofamid resistance: a point mutation (L201S) and more strikingly, two insertions (E203-DE-V204, E203-VE-V204). In parallel with the classical tools, pyrosequencing and qPCR, we then benchmarked short and long-reads NGS technologies (Ion Torrent, Illumina, Oxford Nanopore Technologies) to sequence the complete cytb with a view to detecting and assessing the proportion of resistant variants of P. viticola at the scale of a field population. Eighteen populations collected from French vineyard fields in 2020 were analysed: 12 showed a variable proportion of G143A, 11 of E203-DE-V204 and 7 populations of the S34L variant that confers resistance to ametoctradin. Interestingly, the long reads were able to identify variants, including SNPs, with confidence and to detect a small proportion of P. viticola with multiple variants along the same cytb sequence. Overall, NGS appears to be a promising method for assessing fungicide resistance of pathogens linked to cytb modifications at the field population level. This approach could rapidly become a robust decision support tool for resistance management in the future.


Assuntos
Fungicidas Industriais , Oomicetos , Vitis , Citocromos b/genética , Complexo III da Cadeia de Transporte de Elétrons/genética , Fazendas , Fungicidas Industriais/farmacologia , Oomicetos/genética , Doenças das Plantas/microbiologia , Estrobilurinas/farmacologia , Vitis/microbiologia
2.
Toxins (Basel) ; 15(1)2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36668865

RESUMO

Pathogenic fungi in the genera Alternaria, Aspergillus, Botrytis, Fusarium, Geotrichum, Gloeosporium, Monilinia, Mucor, Penicillium, and Rhizopus are the most common cause of pre- and postharvest diseases of fruit, vegetable, root and grain commodities. Some species are also able to produce mycotoxins, secondary metabolites having toxic effects on human and non-human animals upon ingestion of contaminated food and feed. Synthetic fungicides still represent the most common tool to control these pathogens. However, long-term application of fungicides has led to unacceptable pollution and may favour the selection of fungicide-resistant mutants. Microbial biocontrol agents may reduce the incidence of toxigenic fungi through a wide array of mechanisms, including competition for the ecological niche, antibiosis, mycoparasitism, and the induction of resistance in the host plant tissues. In recent years, the emission of volatile organic compounds (VOCs) has been proposed as a key mechanism of biocontrol. Their bioactivity and the absence of residues make the use of microbial VOCs a sustainable and effective alternative to synthetic fungicides in the management of postharvest pathogens, particularly in airtight environments. In this review, we will focus on the possibility of applying yeast VOCs in the biocontrol of mycotoxigenic fungi affecting stored food and feed.


Assuntos
Armas de Fogo , Fungicidas Industriais , Micotoxinas , Perfumes , Compostos Orgânicos Voláteis , Animais , Micotoxinas/metabolismo , Saccharomyces cerevisiae/metabolismo , Compostos Orgânicos Voláteis/farmacologia , Compostos Orgânicos Voláteis/metabolismo , Fungicidas Industriais/farmacologia , Fungos/metabolismo , Alternaria/metabolismo
3.
Molecules ; 28(2)2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36677619

RESUMO

Thirty novel diamide compounds combining pyrazolyl and polyfluoro-substituted phenyl groups into alanine or 2-aminobutyric acid skeletons were designed and synthesized with pyflubumide as the lead compound to develop potent and environmentally friendly pesticides. The preliminary bioassay results indicated that the new compounds containing the para-hexa/heptafluoroisopropylphenyl moiety exhibit fungicidal, insecticidal, and acaricidal activities. This is the first time that the para-hexa/heptafluoroisopropylphenyl group is a key fragment of the fungicidal activity of new N-phenyl amide compounds. Most of the target compounds exhibited moderate to good insecticidal activity against Aphis craccivora at a concentration of 400 µg/mL, and some showed moderate activity at a concentration of 200 µg/mL; in particular, compounds I-4, II-a-10, and III-26 displayed higher than 78% lethal rates at 200 µg/mL. Compound II-a-14 exhibited a 61.1% inhibition at 200 µg/mL for Tetranychus cinnabarinus. In addition, some of the target compounds exhibited good insecticidal activities against Plutella xylostella at a concentration of 200 µg/mL; the mortalities of compounds I-1, and II-a-15 were 76.7% and 70.0%, respectively. Preliminary analysis of the structure-activity relationship (SAR) indicated that the insecticidal and acaricidal activities varied significantly depending on the type of substituent and substitution pattern. The fungicidal activity results showed that compounds I-1, II-a-10, II-a-17, and III-26 exhibited good antifungal effects. Enzymatic activity experiments and in vivo efficacy of compound II-a-10 were conducted and discussed.


Assuntos
Acaricidas , Fungicidas Industriais , Inseticidas , Mariposas , Animais , Inseticidas/farmacologia , Diamida/farmacologia , Alanina/farmacologia , Desenho de Fármacos , Relação Estrutura-Atividade , Fungicidas Industriais/farmacologia , Estrutura Molecular
4.
Sci Rep ; 13(1): 1280, 2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36690688

RESUMO

Synthetic fungicides are necessary evil in crop production, their usage cannot be neglected or abandoned but must be alternated/supplemented with other control measures such as cultural, host resistance and biocontrol methods to reduce their detrimental effect on the environment and living organisms. A bioproduct (wood vinegar) was evaluated against oil palm seedling pathogens at CSIR-Oil Palm Research Institute, Kusi at different concentrations and compared with an inorganic fungicide at the manufacturer's recommended dosage. Disease pathogens were isolated from collected diseased leaf samples and pure cultures were established on cPDA. PDA was amended with wood vinegar ranging from 0 to 3.35% and 0.1%v/v of carbendazim as a positive control. Daily colony growth was measured in two diagonal lengths and averages of day 6 and day 7 were used to calculate the inhibition percentage for both pathogens. 11 mm/day was the lowest average growth rate recorded for 2.68% v/v of wood vinegar and 14.17 mm/day on control plate of Curvularia species. There was no significant difference between 0.1%v/v carbendazim, 2.68 and 3.35% v/v against Curvularia species whilst significantly, there was difference between 0.1%v/v carbendazim and 2.68 and 3.35%v/v of wood vinegar against Pestalotiopsis species.


Assuntos
Fungicidas Industriais , Plântula , Agricultura Orgânica , Fungicidas Industriais/farmacologia , Óleo de Palmeira
5.
PLoS One ; 18(1): e0280064, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36652427

RESUMO

Advances in biocontrol potentials and fungicide resistance are highly desirable for Trichoderma. Thus, it is profitable to use mutagenic agents to develop superior strains with enhanced biocontrol properties and fungicide tolerance in Trichoderma. This study investigates the N-methyl-n-nitro-N-nitrosoguanidine (NTG) (100 mg/L) induced mutants of Trichoderma asperellum. Six NTG (3 each from 1st & 2nd round) induced mutants were developed and evaluated their biocontrol activities and carbendazim tolerance. Among the mutant N2-3, N2-1, N1 and N2-2 gave the best antagonistic and volatile metabolite activities on inhibition of chickpea F. oxysporum f. sp. ciceri, B. cinerea and R. bataticola mycelium under in vitro condition. Mutant N2-2 (5626.40 µg/ml) showed the highest EC50 value against carbendazim followed by N2-3 (206.36 µg/ml) and N2-1 (16.41 µg/ml); and succeeded to sporulate even at 2000 µg/ml of carbendazim. The biocontrol activity of N2-2 and N2 with half-dose of carbendazim was evaluated on chickpea dry root rot under controlled environment. Disease reduction and progress of the dry root rot was extremely low in T7 (N2-2 + with half-dose of carbendazim) treatment. Further, carbendazim resistant mutants demonstrated mutation in tub2 gene of ß-tubulin family which was suggested through the 37 and 183 residue changes in the superimposed protein structures encoded by tub2 gene in N2 and N2-2 with WT respectively. This study conclusively implies that the enhanced carbendazim tolerance in N2-2 mutant did not affect the mycoparasitism and plant growth activity of Trichoderma. These mutants were as good as the wild-type with respect to all inherent attributes.


Assuntos
Cicer , Fungicidas Industriais , Trichoderma , Fungicidas Industriais/farmacologia , Cicer/genética , Melhoramento Genético , Antibiose , Trichoderma/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/prevenção & controle
6.
Int J Mol Sci ; 24(2)2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36674501

RESUMO

Botrytis cinerea, the causal agent of gray mold, is one of the most destructive pathogens of cherry tomatoes, causing fruit decay and economic loss. Fludioxonil is an effective fungicide widely used for crop protection and is effective against tomato gray mold. The emergence of fungicide-resistant strains has made the control of B. cinerea more difficult. While the genome of B. cinerea is available, there are few reports regarding the large-scale functional annotation of the genome using expressed genes derived from transcriptomes, and the mechanism(s) underlying such fludioxonil resistance remain unclear. The present study prepared RNA-sequencing (RNA-seq) libraries for three B. cinerea strains (two highly resistant (LR and FR) versus one highly sensitive (S) to fludioxonil), with and without fludioxonil treatment, to identify fludioxonil responsive genes that associated to fungicide resistance. Functional enrichment analysis identified nine resistance related DEGs in the fludioxonil-induced LR and FR transcriptome that were simultaneously up-regulated, and seven resistance related DEGs down-regulated. These included adenosine triphosphate (ATP)-binding cassette (ABC) transporter-encoding genes, major facilitator superfamily (MFS) transporter-encoding genes, and the high-osmolarity glycerol (HOG) pathway homologues or related genes. The expression patterns of twelve out of the sixteen fludioxonil-responsive genes, obtained from the RNA-sequence data sets, were validated using quantitative real-time PCR (qRT-PCR). Based on RNA-sequence analysis, it was found that hybrid histidine kinase, fungal HHKs, such as BOS1, BcHHK2, and BcHHK17, probably involved in the fludioxonil resistance of B. cinerea, in addition, a number of ABC and MFS transporter genes that were not reported before, such as BcATRO, BMR1, BMR3, BcNMT1, BcAMF1, BcTOP1, BcVBA2, and BcYHK8, were differentially expressed in the fludioxonil-resistant strains, indicating that overexpression of these efflux transporters located in the plasma membranes may associate with the fludioxonil resistance mechanism of B. cinerea. All together, these lines of evidence allowed us to draw a general portrait of the anti-fludioxonil mechanisms for B. cinerea, and the assembled and annotated transcriptome data provide valuable genomic resources for further study of the molecular mechanisms of B. cinerea resistance to fludioxonil.


Assuntos
Fungicidas Industriais , Transcriptoma , Fungicidas Industriais/farmacologia , Fungicidas Industriais/metabolismo , Perfilação da Expressão Gênica , Botrytis , Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , RNA/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Farmacorresistência Fúngica/genética
7.
Int J Mol Sci ; 24(2)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36674895

RESUMO

Calcium/calmodulin-dependent protein kinase (CaMK), a key downstream target protein in the Ca2+ signaling pathway of eukaryotes, plays an important regulatory role in the growth, development and pathogenicity of plant fungi. Three AaCaMKs (AaCaMK1, AaCaMK2 and AaCaMK3) with conserved PKC_like superfamily domains, ATP binding sites and ACT sites have been cloned from Alternaria alternata, However, their regulatory mechanism in A. alternata remains unclear. In this study, the function of the AaCaMKs in the development, infection structure differentiation and pathogenicity of A. alternata was elucidated through targeted gene disruption. The single disruption of AaCaMKs had no impact on the vegetative growth and spore morphology but significantly influenced hyphae growth, sporulation, biomass accumulation and melanin biosynthesis. Further expression analysis revealed that the AaCaMKs were up-regulated during the infection structure differentiation of A. alternata on hydrophobic and pear wax substrates. In vitro and in vivo analysis further revealed that the deletion of a single AaCaMKs gene significantly reduced the A. alternata conidial germination, appressorium formation and infection hyphae formation. In addition, pharmacological analysis confirmed that the CaMK specific inhibitor, KN93, inhibited conidial germination and appressorium formation in A. alternata. Meanwhile, the AaCaMKs genes deficiency significantly reduced the A. alternata pathogenicity. These results demonstrate that AaCaMKs regulate the development, infection structure differentiation and pathogenicity of A. alternata and provide potential targets for new effective fungicides.


Assuntos
Fungicidas Industriais , Pyrus , Pyrus/microbiologia , Virulência/genética , Alternaria , Fungicidas Industriais/farmacologia , Fungicidas Industriais/metabolismo
8.
Molecules ; 28(1)2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36615609

RESUMO

The addition of active groups of known fungicides, or systemic acquired resistance inducers, into novel compound molecules to search for potential antifungal compounds is a popular and effective strategy. In this work, a new series of N-acyl-N-arylalanines was developed and synthesized, in which 1,2,3-thiadiazol-5-ylcarbonyl or 3,4-dichloroisothiazol-5-ylcarbonyl (fragments from synthetic plant resistance activators tiadinil and isotianil, respectively) and a fragment of N-arylalanine, the toxophoric group of acylalanine fungicides. Several new synthesized compounds have shown moderate antifungal activity against fungi in vitro, such as B. cinerea, R. solani and S. sclerotiorum. In vivo tests against A. brassicicola showed that compound 1d was 92% effective at a concentration of 200 µg/mL, similar to level of tiadinil, a known inducer of systemic resistance. Thus, 1d could be considered a new candidate fungicide for further detailed study. The present results will advance research and influence the search for more promising fungicides for disease control in agriculture.


Assuntos
Fungicidas Industriais , Tiadiazóis , Fungicidas Industriais/farmacologia , Antifúngicos/farmacologia , Estrutura Molecular , Tiadiazóis/farmacologia , Plantas , Relação Estrutura-Atividade
9.
Sci Rep ; 13(1): 802, 2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36646732

RESUMO

Integrating toxic fungicide into a functional stimuli-responsive nanosystem can effectively improve the fungus control specificity and reduce the effect on non-target organisms. We report here a redox and cellulase dual-responsive multifunctional nanoparticle based on bimodal mesoporous silica (BMMs) to deliver prochloraz (Pro) for the smart management of wilt disease (Pro-AC-SS-BMMs, known as P-ASB). The surface of the nanocarrier was modified with an aminosilane coupling agent, and Pro was encapsulated by physical adsorption using 2,2'-dithiodiacetic acid as a smart bridge and disulfide (SS) cross-linked aminocellulose (AC) as gatekeepers. P-ASB nanoparticles (NPs) had a spherical structure, and the size was 531.2 ± 4.9 nm. The loading rate of Pro was 28.5%, and the NPs possessed excellent redox/cellulase dual-responsive release characteristics in the presence of glutathione (GSH) and cellulase. The nanocarrier could effectively protect Pro against photodegradation and had better foliar wettability than the Pro technical. Fluorescence tracer results showed that the nanocarriers were taken up and activated by the mycelium. P-ASB NPs had better control efficacy against Rhizoctonia solani and had no significant toxicity to cells and bacteria. This study provides a new strategy for enhancing the environmental protection and promoting the development of green agriculture.


Assuntos
Celulases , Fungicidas Industriais , Nanopartículas , Preparações de Ação Retardada/farmacologia , Fungicidas Industriais/farmacologia , Dióxido de Silício/química , Nanopartículas/química , Oxirredução , Porosidade , Doxorrubicina/química
10.
J Agric Food Chem ; 71(1): 920-933, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36534960

RESUMO

The development of new green fungicides is an effective way to solve the resistance of agricultural pathogens and plays an important role in promoting high-quality and sustainable development of modern agriculture. In this project, a series of aryloxy-, arylthio-, and arylamino-containing acethydrazide derivatives were designed, synthesized, and characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, and high-resolution mass spectrometry (HRMS). The fungicidal bioassays indicated that some compounds showed excellent and broad-spectrum fungicidal activity, and the structure-activity relationship was discussed. The in vivo fungicidal activity demonstrated that compounds C4 and D8 exhibited good preventative effects against Fusarium graminearum infecting wheat leaves, of which the preventative activity of compound D8 was almost equal to that of the positive agents. Transmission electron microscopy (TEM) observation revealed that the plasma membrane in the C4-treated F. graminearum hyphal cells was severely contracted and separated with the cell wall, coupling with the visible lysosomes and the disappeared cytoplasm and organelles, which may be the reasons for the shriveled and even ruptured hyphae observed by scanning electron microscopy (SEM). Subsequently, transcriptomics and metabolomics were performed to further elucidate the fungicidal mechanism. The regulatory networks of differential genes and metabolites in plasma membrane-related sphingolipid metabolism, linoleic acid metabolism, α-linoleic acid metabolism, and arachidonic acid metabolism were constructed and elaborated. Additionally, preliminary investigation of seeding growth suggested that compounds C4 and D8 may have different degrees of influence on the growth indicators of wheat seedlings; however, this effect may be negligible as the plant grows.


Assuntos
Fungicidas Industriais , Fungicidas Industriais/farmacologia , Fungicidas Industriais/química , Ácido Linoleico , Doenças das Plantas/prevenção & controle , Relação Estrutura-Atividade , Espectroscopia de Ressonância Magnética
11.
J Agric Food Chem ; 71(1): 174-185, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36562624

RESUMO

To discover novel fungicidal agrochemicals for treating wheat scab, 39 novel camphor sulfonohydrazide/sulfonamide derivatives 4a-4t and 6a-6s were designed and synthesized. In the in vitro antifungal/antioomycete assay, compounds 4g, 4n, and 4o displayed significant inhibitory activities against Fusarium graminearum, Botryosphaeria dothidea, and Phytophthora capsici. Among them, 4n exhibited the best antifungal activity against F. graminearum with an EC50 value of 0.41 mg/L, which was at the same level as that of pydiflumetofen. The in vivo experiment revealed that 4n presented excellent protective and curative efficacy toward F. graminearum. In the antifungal mechanism study, 4n could increase the cell membrane permeability and reduce the exopolysaccharide and ergosterol content of F. graminearum. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed that 4n could significantly damage the surface morphology and the cell ultrastructure of mycelia to interfere with the growth of F. graminearum. Furthermore, 4n exhibited potent succinate dehydrogenase (SDH) inhibitory activity in vitro with an IC50 value of 3.94 µM, which was equipotent to pydiflumetofen (IC50 = 4.07 µM). The molecular dynamics simulation and docking study suggested that compound 4n could well occupy the active site and form strong interactions with the key residues of SDH. The above-mentioned results demonstrated that the title camphor sulfonohydrazide/sulfonamide derivatives could be promising lead compounds for further succinate dehydrogenase inhibitor (SDHI) fungicide development.


Assuntos
Fungicidas Industriais , Phytophthora , Antifúngicos/farmacologia , Antifúngicos/química , Relação Estrutura-Atividade , Cânfora , Succinato Desidrogenase , Fungicidas Industriais/farmacologia , Fungicidas Industriais/química , Phytophthora/metabolismo , Simulação de Acoplamento Molecular
12.
Pestic Biochem Physiol ; 189: 105313, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36549825

RESUMO

Picolinamide and strobilurin fungicides bind to the Qi and Qo sites on cytochrome b, respectively, and target many of the same plant pathogens. Using Saccharomyces cerevisiae as a model system, we explore effects of amino acid changes at each site on sensitivity to a fungicide acting at the opposite site and examine the relationship between altered sensitivity and growth penalty. In addition, double mutants containing the G143A or F129L mutations responsible for strobilurin resistance in combination with Qi site mutations that confer resistance to picolinamides are characterized in terms of their sensitivity to QiI and QoI fungicides and growth rate. Mutants containing amino acid changes at the Qo site varied in their growth rate and sensitivity to the picolinamide CAS-649, and increased sensitivity was associated with a greater growth penalty. Conversely, changes at the Qi site affected sensitivity to azoxystrobin and also showed a correlation between increased sensitivity and reduced growth. There was no overall correlation between resistance to azoxystrobin and CAS-649 among mutants, however negative cross-resistance occurred in the case of mutations which conferred resistance to either compound and also carried a growth penalty. These results suggest the use of QoI fungicides to delay the emergence of pathogen resistance to QiIs, and vice versa. Double mutants containing G143A or F129L in combination with Qi site changes N31K, G37C/V or L198F that cause resistance to picolinamides generally exhibited lower resistance factors for both azoxystrobin and CAS-649 than corresponding resistant strains with a single mutation. Reduced growth was observed for all F129L-containing double mutants, whereas the growth rate of double mutants containing G143A was significantly reduced only by the Qi site mutations N31K and G37V that confer a larger growth penalty. Our results suggest that resistance to picolinamides in pathogens could emerge more readily in a strobilurin-sensitive genetic background than in a strobilurin-resistant one.


Assuntos
Fungicidas Industriais , Fungicidas Industriais/farmacologia , Estrobilurinas , Saccharomyces cerevisiae/genética , Mutação , Farmacorresistência Fúngica/genética
13.
J Microbiol Methods ; 204: 106653, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36503052

RESUMO

Assessment of the sensitivity of non-sporulating fungi to fungicides through amended-media assays is labor intensive. As an alternative, we developed an absorbance assay using 96-well microplates to assess the sensitivity of Clarireedia jacksonii, a non-sporulating fungus, to the fungicide propiconazole based on the change in absorbance corresponding to fungal growth. This microplate assay can allow for the assessment of multiple isolates of C. jacksonii at different concentrations of a fungicide with many technical replications in a single plate. Three methods for inoculating microplate wells were compared. The "microplug" method was the simplest to perform, requiring only a micropipette with 1 ml tips. EC50 values from this microplate assay were compared to those of a traditional amended agar assay using 30 isolates of C. jacksonii with varying sensitivity to propiconazole. The non-transformed relationship between the two assays was low but weakly significant (R2 = 0.137, p = 0.037). However, correlation of log10 transformed EC50 values from both assays revealed a stronger and highly significant relationship (R2 = 0.56, p < 0.001). Additionally, the microplate assay appears to be more sensitive in detecting resistance (EC50 > 0.1 µg/ml), and revealed five of the assessed isolates to be resistant to propiconazole that were not found as such with the amended agar assay. These results imply that EC50 results from the microplate assay were not exactly equivalent to the amended agar assay for estimating EC50 values, but it may be useful in assigning or confirming general sensitivity classifications.


Assuntos
Fungicidas Industriais , Fungicidas Industriais/farmacologia , Ágar , Bioensaio
14.
Plant Dis ; 106(4): 1167-1174, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34546773

RESUMO

Cucurbit production in Florida is impacted by downy mildew on a yearly basis. Cucurbit downy mildew (CDM), caused by Pseudoperonospora cubensis, is one of the most devastating cucurbit diseases and can lead to complete yield loss. Nearly continuous production of cucurbits occurs temporally throughout Florida, which puts extensive pressure on the pathogen population to select for individuals that are resistant to fungicides in use labeled for CDM. Loss of efficacy as a result of fungicide resistance developing is becoming a major concern for Florida cucurbit growers who rely on these products to manage CDM. This study was established to evaluate the field activity of 11 utilized fungicides by determining their duration of activity when applied at various intervals for the management of CDM in cucumber under Florida field conditions. By comparing levels of percent CDM control and area under the disease progress curve values, the fungicide's duration of field activity was established. Field activities were <1 week for dimethomorph and fluopicolide; 1 week for cymoxanil; 1 to 2 weeks for chlorothalonil and mancozeb; 2 weeks for ethaboxam; 1 to 3 weeks for propamocarb, cyazofamid, and ametoctradin + dimethomorph; and 2 to 4 weeks for oxathiapiprolin and fluazinam. Knowledge of duration of field activity can potentially improve the development of CDM management programs and slow the resistance selection.


Assuntos
Cucumis sativus , Fungicidas Industriais , Oomicetos , Peronospora , Florida , Fungicidas Industriais/farmacologia , Doenças das Plantas/prevenção & controle
15.
Zhongguo Zhong Yao Za Zhi ; 47(22): 6042-6049, 2022 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-36471928

RESUMO

The leaf spot of Belamcanda chinensis often appears in May to June and spreads rapidly during the flowering stage(July to September) in the cultivation fields, seriously affecting the yield and quality of B. chinensis. To identify and characterize the pathogens of the leaf spot, we isolated two species of Alternaria, identified them according to Koch's postulates, and tested their pathogenicity and biological characteristics. Furthermore, we determined the inhibitory effects of 6 chemical fungicides, 1 plant fungicide, and 3 microbial fungicides on the pathogens by using mycelial growth rate and plate confrontation method to select the appropriate control agents. The results showed that the two pathogens causing B. chinensis leaf spot were Alternaria tenuissima and A. alternata. The conidia of A. tenuissima often formed long chains with no or a few branches, while those of A. alternata often formed short branched chains. The optimum growth temperature of both A. tenuissima and A. alternata was 25 ℃. The two pathogens grew well in alkaline environment. The indoor fungicide screening experiments showed that 40% flusilazole had good inhibitory effects on the two pathogens, with the EC_(50) values of 12.42 mg·L~(-1) and 12.78 mg·L~(-1) for A. tenuissima and A. alternata, respectively. The results of this study provide a theoretical basis for the subsequent theoretical research and field control of B. chinensis leaf spot.


Assuntos
Fungicidas Industriais , Iris (Planta) , Fungicidas Industriais/farmacologia , Pesquisa , Esporos Fúngicos , Micélio
16.
Zhongguo Zhong Yao Za Zhi ; 47(19): 5209-5216, 2022 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-36472027

RESUMO

In summer in 2020, Pinellia ternata in many planting areas in Hubei suffered from serious southern blight, as manifested by the yellowing and wilted leaves and rotten tubers. This study aims to identify the pathogen, clarify the biological characteristics of the pathogen, and screen fungicides. To be specific, the pathogen was isolated, purified, and identified, and the pathogenicity was detected according to the Koch's postulates. Moreover, the biological characteristics of the pathogen were analyzed. Furthermore, PDA plates and seedlings were used to determine the most effective fungicides. The results showed that the mycelia of the pathogen were white and villous with silk luster, which produced a large number of white to black brown sclerotia. The pathogen was identified as Athelia rolfsii by morphological observation and molecular identification based on LSU and TEF gene sequences. The optimum growth conditions for A. rolfsii were 30 ℃ and pH 5-8, and the optimum conditions for the germination of sclerotia were 25 ℃ and pH 7-9. Bacillus subtilis, difenoconazole, and flusilazole were identified as effective fungicides with PDA, and their half maximal effective concentration(EC_(50)) was all less than 5 mg·L~(-1). The effective fungicides screened with the seedlings were hymexazol and difenoconazole. Based on the screening experiments, difenoconazole can be used as the main agent for the prevention and treatment of southern blight.


Assuntos
Fungicidas Industriais , Pinellia , Pinellia/genética , Fungicidas Industriais/farmacologia , Plântula , Bacillus subtilis , Micélio
17.
Food Res Int ; 162(Pt A): 111935, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36461193

RESUMO

Fungi and oomycetes found in vineyards cause diseases such as powdery and downy mildew. Consequently, conventional and alternative agronomical practices are widely used prior to harvest to protect grapes. Alternative products are considered more eco-friendly and environmentally sustainable in comparison to conventional chemical products. However, the effect of these alternative products on yeast ecology, from the vineyard to the winery, is poorly understood. This study compared the effect of alternative and conventional chemical antifungal compounds (copper and sulphur based) on grapes' mycobiota in the vineyard and during subsequent winery fermentation using culture-dependent and -independent approaches. Culture-dependent data indicated a treatment-dependent effect on the load and diversity of yeast populations on grapes. It was found that the population of Hanseniaspora uvarum was higher on grapes previously treated with laminarin and copper, compared to the other levels registered on grapes previously treated with the rest of antifungal products tested in this study (including the untreated and conventional treatment controls). Concerning, wine quality, the chemical composition was not correlated to the application of antifungal treatment in the vineyard. Understanding the effect of different antifungal products on grape and wine microbial communities may help in setting up guidelines for wine grape production. These guidelines, can be used to guarantee quality in the pursuit of a sustainable competitive advantage in the market.


Assuntos
Fungicidas Industriais , Vitis , Fazendas , Fungicidas Industriais/farmacologia , Antifúngicos , Cobre , Biodiversidade
18.
Pestic Biochem Physiol ; 188: 105287, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36464340

RESUMO

The application of fungicide mixture is one of the most important measures to extend the service life of highly selective fungicides. Pyraclostrobin (PYR), which has been extensively used to control plant diseases by inhibiting mitochondrial respiration of pathogenic fungi, is at a high risk of resistance development. In this study, the potential of PYR alone or in combination with cystamine, an inhibitor of microbial transglutaminase, to suppress Fusarium graminearum was tested in vitro and in vivo. A synergistic effect of PYR/CYS mixture was observed both in vitro and when applied to etiolated wheat coleoptile. The control effect of PYR/CYS mixture on F. graminearum was better than that of PYR alone, which was reflected by the increased protection effect. The discrepancies of membrane permeability and the redox-physiological state were observed between PYR and PYR/CYS treatments, suggesting that an increased PYR availability in F. graminearum mycelia could be related with the observed synergistic action. Moreover, a synergistic profile was observed between PYR and CYS in regard of massive autophagosomes in mycelia, indicating that enhanced autophagy could be involved in the mode of action of PYR/CYS mixture. The differential content of mitochondrial metabolites between PYR and PYR/CYS treatments also provided evidence for CYS contribution to the fungicidal action of PYR/CYS mixture. The results provide insight into the synergistic mechanism of action of PYR/CYS mixture and an effective way to enhance the efficiency of PYR to combat F. graminearum.


Assuntos
Cistamina , Fungicidas Industriais , Autofagia , Fungicidas Industriais/farmacologia , Permeabilidade
19.
Pestic Biochem Physiol ; 188: 105227, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36464347

RESUMO

Due to recent evidence of Aspergillus uvarum pathogenicity on wine grapes and variable fungicide sensitivity to quinone outside inhibitor (QoI) fungicides, the identity and QoI sensitivity of Aspergillus isolates from the Mid-Atlantic United States was investigated. Phylogenic analysis of 31 isolates revealed 26 as A. uvarum and 5 as A. japonicus, both of which have been previously isolated from grape. The A. uvarum isolates had variable sensitivities to the QoI azoxystrobin, and the genomic region that codes for the target of QoIs, cytochrome b, was sequenced. Translation of the cytochrome b coding sequence revealed that the most resistant isolates (termed cytb3) contained three mutations, S108A, F129L, and A194V, and the moderately sensitive isolates (termed cytb2) contained two mutations S108A and A194V. This is the first report of an amino acid variation in cytochrome b at position 108. Cytb3 isolates were significantly less inhibited than the cytb2 and wild-type isolates (cytbWT) in vitro, and were significantly less inhibited than the cytbWT isolates on detached fruit. Molecular docking analysis revealed similar differences, with azoxystrobin binding most securely in the cytbWT variant of cytochrome b than cytb2 and cytb3. As Aspergillus rot has not been a target disease of fungicide sprays in the U.S., the selection of resistant phenotypes is likely resultant from sprays for other diseases. Resistance is of concern due to the pathogenicity of A. uvarum and A. japonicus on wine grapes, and the ability of these species to be mycotoxigenic or pathogenic for humans.


Assuntos
Fungicidas Industriais , Vitis , Humanos , Estações do Ano , Citocromos b/genética , Simulação de Acoplamento Molecular , Aspergillus/genética , Fungicidas Industriais/farmacologia , Quinonas
20.
World J Microbiol Biotechnol ; 39(1): 34, 2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36469148

RESUMO

Gray blight, a fungal disease caused by Pestalotiopsis-like species, is a widespread disease affecting tea crop (Camellia sinensis (L.) Kuntze) in many tea-growing countries, including India, resulting in huge losses in tea production. In India, several studies have been conducted to understand the fungal diseases of tea crop, but gray blight has not been well described in major tea growing areas such as in North Bengal, based on its geographic distribution, molecular analysis, or pathogenicity, and even fungicide resistance. The objective of this study was to identify and characterize the causative agents of gray blight disease in symptomatic leaf sample of tea crop collected from 27 tea gardens located in North Bengal, India and to evaluate some common fungicides against them in order to understand the resistance mechanism. In this study, we characterized Pestalotiopsis-like species based on the phylogenies of DNA sequences (internal transcribed spacers) and assessment of conidial characteristics. The study revealed that out of 27 isolates of gray blight pathogens, 17 belonged to the genus Pseudopestalotiopsis (Ps.), six isolates were Neopestalotiopsis, and four were Pestalotiopsis. Two novel species, Ps. thailandica and N. natalensis were introduced through this study. The most frequently isolated genus from C. chinensis was Pseudopestalotiopsis. Pathogenicity tests showed that the isolates displayed significantly different virulence when inoculated onto wounded tea leaves and the mycelial growth rate was positively correlated with pathogenicity (P < 0.01). Based on the 13 ISSR (Inter Simple Sequence Repeat) markers used and principal coordinate analysis, it was found that isolates were very diverse. Out of 27 isolates, IND0P2, DLG0P10, and BHAT0P11 isolates were insensitive against both MBC + M3 (Carbendazim + Mancozeb) and DMI (Hexaconazole) fungicides, while isolates SANY0P18, PAHG0P19, RANG0P24, and SING0P25 were insensitive only against MBC + M3 fungicide. Further, these insensitive isolates were grouped into separate clusters by ISSR, indicating their distinctiveness. However, all the evaluated isolates were susceptible to M1 (copper oxychloride) and another DMI (propiconazole) fungicides. Therefore, to manage gray blight, fungicide resistance management strategies as recommended by Fungicide Resistance Action Committee should be implemented.


Assuntos
Camellia sinensis , Fungicidas Industriais , Xylariales , Fungicidas Industriais/farmacologia , Pestalotiopsis , Doenças das Plantas/microbiologia , Camellia sinensis/microbiologia , Chá
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...