ABSTRACT
Pseudomonas syringae pv. tomato is a seedborne pathogen that causes bacterial speck disease in tomato. P. syringae pv. tomato is typically detected in tomato seed using quantitative real-time PCR (qPCR) but the inability of qPCR to distinguish between viable and nonviable cells might lead to an overestimation of viable P. syringae pv. tomato cells. In the present study, a strategy involving a propidium monoazide (PMA) pretreatment followed by a qPCR (PMA-qPCR) assay was developed for quantifying viable P. syringae pv. tomato cells in contaminated tomato seed. PMA could selectively bind to the chromosomal DNA of dead bacterial cells and, therefore, block DNA amplification of qPCR. The primer pair Pst3F/Pst3R was designed based on gene hrpZ to specifically amplify and quantify P. syringae pv. tomato by qPCR. The PMA pretreatment protocol was optimized for selectively detecting viable P. syringae pv. tomato cells, and the optimal PMA concentration and light exposure time were 10 µmol liter-1 and 10 min, respectively. In the sensitivity test, the detection limit of PMA-qPCR for detecting viable cells in bacterial suspension and artificially contaminated tomato seed was 102 CFU ml-1 and 11.86 CFU g-1, respectively. For naturally contaminated tomato seed, viable P. syringae pv. tomato cells were quantified in 6 of the 19 samples, with infestation levels of approximately 102 to 104 CFU g-1. The results indicated that the PMA-qPCR assay is a suitable tool for quantifying viable P. syringae pv. tomato cells in tomato seed, which could be useful for avoiding the potential risks of primary inoculum sources from contaminated seed.
Subject(s)
Solanum lycopersicum , Azides , Propidium/analogs & derivatives , Pseudomonas syringae , Real-Time Polymerase Chain Reaction , SeedsABSTRACT
A series of novel pyrazole amide derivatives were designed and synthesized by multi-step reactions from phenylhydrazine and ethyl 3-oxobutanoate as starting materials, and their structures were characterized by NMR, MS and elemental analysis. The antifungal activity of the title compounds was determined. The results indicated that some of title compounds exhibited moderate antifungal activity. Furthermore, DFT calculations were used to study the structure-activity relationships (SAR).
Subject(s)
Acetoacetates/chemistry , Amides/chemical synthesis , Antifungal Agents/chemical synthesis , Phenylhydrazines/chemistry , Pyrazoles/chemical synthesis , Amides/pharmacology , Antifungal Agents/pharmacology , Botrytis/drug effects , Botrytis/growth & development , Drug Design , Microbial Sensitivity Tests , Molecular Structure , Phytophthora infestans/drug effects , Phytophthora infestans/growth & development , Pyrazoles/pharmacology , Pythium/drug effects , Pythium/growth & development , Quantum Theory , Rhizoctonia/drug effects , Rhizoctonia/growth & development , Structure-Activity RelationshipABSTRACT
Identification of plant-pathogenic fungi is time-consuming due to cultivation and microscopic examination and can be influenced by the interpretation of the micro-morphological characters observed. The present investigation aimed to create a simple but sophisticated method for the identification of plant-pathogenic fungi by Fourier transform infrared (FTIR) spectroscopy. In this study, FTIR-attenuated total reflectance (ATR) spectroscopy was used in combination with chemometric analysis for identification of important pathogenic fungi of horticultural plants. Mixtures of mycelia and spores from 27 fungal strains belonging to nine different families were collected from liquid PD or solid PDA media cultures and subjected to FTIR-ATR spectroscopy measurements. The FTIR-ATR spectra ranging from 4 000 to 400 cm-1 were obtained. To classify the FTIR-ATR spectra, cluster analysis was compared with canonical vitiate analysis (CVA) in the spectral regions of 3 050ï½2 800 and 1 800ï½900 cm-1. Results showed that the identification accuracies achieved 97.53% and 99.18% for the cluster analysis and CVA analysis, respectively, demonstrating the high potential of this technique for fungal strain identification.
Subject(s)
Spectroscopy, Fourier Transform Infrared , Cluster Analysis , Fungi , Mycelium , PlantsABSTRACT
Clubroot, caused by Plasmodiophora brassicae, is considered the most devastating soilborne disease in Brassica crops. It has emerged as a serious disease threatening the cruciferous crop production industry in China. Nowadays, the detection techniques for P. brassicae are laborious, time-consuming and low sensitivity. Rapid and effective detection methods are needed. The objective of this study is to develop a Fourier transform infrared spectrometer (FTIR) technique for detection of P. brassicae effectively and accurately. FTIR and Real-time PCR techniques were applied in quantitative detection of P. brassicae. Chinese cabbages were inoculated with P. brassicae. By analyzing the FTIR spectra of P. brassicae, infected clubroots and healthy roots, three specific bands 1 105, 1 145 and 1 228 cm-1 were selected. According to the correlation between the peak areas at these sensitive bands and Real-time PCR Ct value, quantitative evaluation model of P. brassicae was established based on FTIR y=34. 17 +12. 24x - 9. 81x2 - 6. 05x3, r=0. 98 (p<0. 05). To validate accuracy of the model, 10 clubroot samples were selected randomly from field, and detected by FTIR spectrum model, the results showed that the average error is 1. 60%. This demonstrated that the FTIR technology is an available one for the quantitative detection of P. brassicae in clubroot, and it provides a new method for quantitative and quickly detection of Chinese cabbage clubroot.
Subject(s)
Brassica/parasitology , Plant Diseases/parasitology , Plasmodiophorida/isolation & purification , Soil/parasitology , Spectroscopy, Fourier Transform Infrared , Crops, Agricultural/parasitology , Plant Roots/parasitologyABSTRACT
In order to investigate the biological activity of novel 1,2,4-triazole compounds, seventeen novel 1,2,4-triazole derivatives containing pyridine moiety were synthesized under microwave assistant condition by multi-step reactions. The structures were characterized by 1H NMR, MS and elemental analyses. The target compounds were evaluated for their fungicidal activities against Stemphylium lycopersici (Enjoji) Yamamoto, Fusarium oxysporum. sp. cucumebrium, and Botrytis cinerea in vivo, and the results indicated that some of the title compounds displayed excellent fungicidal activities. Theoretical calculation of the title compound was carried out with B3LYP/6-31G (d,p). The full geometry optimization was carried out using 6-31G (d,p) basis set, and the frontier orbital energy, atomic net charges were discussed, and the structure-activity relationship was also studied.
Subject(s)
Antifungal Agents/chemistry , Antifungal Agents/pharmacology , Pyridines/chemistry , Pyridines/pharmacology , Triazoles/chemistry , Triazoles/pharmacology , Antifungal Agents/chemical synthesis , Chemistry Techniques, Synthetic , Fungi/drug effects , Humans , Microwaves , Models, Molecular , Mycoses/drug therapy , Pyridines/chemical synthesis , Triazoles/chemical synthesisABSTRACT
A series of new N,N'-diacylhydrazine derivatives were designed and synthesized. Their structures were verified by 1H-NMR, mass spectra (MS) and elemental analysis. The antifungal activities of these N,N'-diacylhydrazines were evaluated. The bioassay results showed that most of these N,N'-diacylhydrazines showed excellent antifungal activities against Cladosporium cucumerinum, Corynespora cassiicola, Sclerotinia sclerotiorum, Erysiphe cichoracearum, and Colletotrichum orbiculare in vivo. The half maximal effective concentration (EC50) of one of the compounds was also determined, and found to be comparable with a commercial drug. To further investigate the structure-activity relationship, comparative molecular field analysis (CoMFA) was performed on the basis of antifungal activity data. Both the steric and electronic field distributions of CoMFA are in good agreement in this study.
Subject(s)
Antifungal Agents/chemistry , Hydrazines/chemistry , Quantitative Structure-Activity Relationship , Antifungal Agents/chemical synthesis , Antifungal Agents/pharmacology , Chlorophenols/chemistry , Fungi/drug effects , Humans , Hydrazines/chemical synthesis , Hydrazines/pharmacologyABSTRACT
Fourier transform infrared (FTIR) attenuated total reflectance (ATR) spectroscopy was used in combination with multivariate statistic analysis for identification of soil-borne fungi that causes severe economic damage to agriculture: Fusarium monili forme, Fusarium semitectum, Fusarium oxysporum, Fusarium solani, Rhizoctonia solani, Sclerotinia sclerotiorum, Pythium aphanidermatum and Phytophthora capsici. The original FTIR spectra were normalized, and the second derivatives were calculated, from which the peak wave numbers showing greatest variability were selected: 2924, 2854, 1745, 1641, 1547, 1466, 1406, 1376, 1306, 1240, 1201, 1152, 1109 and 1028 cm(-1). To discriminate different fungal strains, canonical discriminant analysis and cluster analysis were performed at these characteristic wave numbers. Results showed that the classification accuracies achieved 100% for different species of fungi, and classification accuracies for different fusarium strains achieved 95.56%, demonstrating the high potential of this technique for fungi identification.
Subject(s)
Fungi/isolation & purification , Soil Microbiology , Spectroscopy, Fourier Transform Infrared , Agriculture , Cluster Analysis , Discriminant Analysis , Fungi/classification , Fusarium , Multivariate AnalysisABSTRACT
Fourier transform infrared spectroscopy (FTIR) technique was applied in the early detection of corynespora spot on cucumber leaves while the symptom had not appeared. The cucumber leaves were inoculated with Corynespora cassiicola. By observing the changes in the FTIR spectra of infected cucumber leaves at various times of post-infection, three sensitive bands, 1 735, 1 545 and 1 240 cm(-1) were selected for the identification of cucumber corynespora leaf spot. According to the peak areas at these sensitive bands, cucumber leaf samples infected with C. cassiicola and control uninfected leaf samples could be classified correctly. Results clearly demonstrated that the FTIR technology is an available one for the early detection of corynespora spot on cucumber leaves while the symptom has not appeared and it provides a new method for the early detection of corynespora spot.
Subject(s)
Cucumis sativus/microbiology , Plant Diseases , Plant Leaves/microbiology , Spectroscopy, Fourier Transform Infrared , AscomycotaABSTRACT
Hyperspectral imaging (400-720 nm) and discriminate analysis were investigated for the detection of normal and diseased cucumber leaf samples with powdery mildew (Sphaerotheca fuliginea), angular leaf spot (Pseudomopnas syringae), downy mildew (Pseudoperonospora cubensis), and brown spot (Corynespora cassiicola). A hyperspectral imaging system was es tablished to acquire and pre-process leaf images, as well as to extract leaf spectral properties. Owing to the complexity of the original spectral data, stepwise discriminate and canonical discriminate were executed to reduce the numerous spectral information, in order to decrease the amount of calculation and improve the accuracy. By the stepwise discriminate we selected 12 optimal wavelengths from the original 55 wavelengths, and after the canonical discriminate, the 55 wavelengths were reduced to 2 canonical variables. Then the discriminate models were developed to classify the leaf samples. The result shows that the stepwise discriminate model achieved classification accuracies of 100% and 94% for the training and testing sets, respectively. For the canonical model, the classification accuracies for the training and testing sets were both 100%. These results indicated that it is feasible to identify and classify cucumber diseases using hyperspectral imaging technology and discriminate analysis. The preliminary study, which was done in a closed room with restrictions to avoid interference of the field environment, showed that there is a potential to establish an online field application in cucumber disease detection based on visible spectroscopy.
Subject(s)
Ascomycota , Cucumis sativus/microbiology , Plant Diseases , Discriminant Analysis , Plant Leaves/microbiology , Spectrum AnalysisABSTRACT
Fourier transform attenuated total reflection infrared spectroscopy (FTIR-ATR) has been a novel technical procedure to identify and classify microorganisms in recent years. In the present study, Fourier transform infrared spectroscopy(FTIR) in combination with an attenuated total reflection (ATR) unit were used to discriminate important plant-destroying fungi. Mycelia of 17 fungal strains belonging to 14 different species were grown on potato dextrose agar (PDA) plants and subjected to FTIR-ATR measurements. High-resolution and well-reproducibility infrared spectra were obtained, and significant spectral differences among these strains were observed in the wavenumber regions of 1800-1485 cm(-1), 1485-1185 cm(-1), and 1185-900 cm(-1). According to the characteristic bands in these regions, cluster analysis was executed to classify the FTIR spectra. The result showed that different fungal strains could be identified correctly, demonstrating the high potential of FTIR-ATR as a tool for fungal strain identification and classification. The method is rapid, inexpensive and reproducible, and requires minimum sample preparation.
Subject(s)
Fungi/classification , Spectroscopy, Fourier Transform Infrared , Cluster Analysis , Mycelium , Reproducibility of ResultsABSTRACT
For a reliable diagnosis of plant diseases and insect pests, spectroscopy analysis technique and mutispectral imaging technique are proposed to diagnose five cucumber diseases, namely Trichothecium roseum, Sphaerotheca fuliginea, Cladosporium cucumerinum, Corynespora cassiicola and Pseudoperonospora cubensis. In the experiment, the cucumbers' multispectral images of 14 visible lights channels, near infrared channel and panchromatic channel were captured using narrow-band multispectral imaging system under standard observation environment. And the 5 cucumber diseases, healthy leaves and reference white were classified using their multispectral information, the distance, angle and relativity. The discrimination of Trichothecium roseum, Sphaerotheca fuliginea, Cladosporium cucumerinum, and reference white was 100%, and that of Pseudoperonospora cubensis and healthy leaves was 80% and 93.33% respectively. The mean correct discrimination of diseases was 81.90% when the distance and relativity were used together. The result shows that the method realized good accuracy in the cucumber diseases diagnosis.
Subject(s)
Cucumis sativus/chemistry , Plant Diseases/classification , Spectrum Analysis/methods , Animals , Plant Leaves/chemistry , Sensitivity and SpecificityABSTRACT
A combined ecological, morphological, and molecular approach was used to examine 26 herbarium specimens and eight strains of Moesziomyces. The phylogenetic analysis resolved eight well-supported clades, of which three contained type specimens of known species of Moesziomyces. One clade contained two specimens that produced a teleomorph in the flowers of Echinochloakimberleyensis in Australia. The name Moesziomyceskimberleyensis is proposed for this smut fungus. Another clade contained specimens that produced sori in the flowers of Leersiahexandra. The name Thecaphoraglobuligera (now Moesziomycesglobuligerus) is available for this species, which is lectotypified. The teleomorph of Moesziomycesantarcticus, previously known only from Japan, is found for the first time in China, on Echinochloacrus-galli.
ABSTRACT
Okra (Abelmoschus esculentus (L.) Moench) has gained more popularity as an economically significant plant for its nutritional and medicinal value, especially in China. During 2014-2016, the root disease of okra was discovered in four okra commercial fields surveyed in China. A fungul was isolated from the infected tissues, and was identified by Verticillium dahliae based on morphological characteristics. Pathogenicity test demonstrated that the fungus was pathogenic on okra, and fulfilled Koch's postulates. The analysis of three sequences revealed 99-100% identity with the reported V. dahliae strain in GenBank. Neighbor-joining analysis of the gene sequences revealed that the representative isolates were clustered with V. dahliae. To the best of our knowledge, this is the first report of Verticillium wilt of okra in China.
ABSTRACT
Severe root rot was observed in fields of cabbages (Brassica oleracea L.) in 2015 in China. Cardinal symptoms of this disease included root rot and wilting leaves. A fungus was isolated from diseased tissues consistently. Based on the morphological features and molecular analysis of the ITS-5.8S rDNA and D1/D2 domain of the 28S rRNA gene, it was identified as Plectosphaerella cucumerina. This is the first report of P. cucumerina causing cabbage root rot in China and the world.
ABSTRACT
BACKGROUND: The increasing prevalence of multi-drug resistant fungal infections has encouraged the search for new antifungal agents. Hydrazone derivatives always exhibited diversity activities, including antifungal, anti-inflammatory, anti-oxidation, anti-cancer activity. Regarding the heterocyclic moiety, 1,2,4-triazolo[4,3-a]pyridine derivatives also display broad activities, such as antifungal activity, anticonvulsant activity, herbicidal activity, antimicrobial activity and anticancer activity. RESULTS: A series of novel 1,2,4-triazolo[4,3-a]pyridine derivatives containing hydrazone moiety were designed and synthesized from 2,3-dichloropyridine, hydrazine hydrate by multi-step reactions under microwave irradiation condition, and their structures were characterized by FT IR, (1)H NMR, (13)C NMR, (19)F NMR, MS and elemental analysis. The antifungal activities of title compounds were determined. The results indicated that some of the title compounds exhibited good antifungal activity. Furthermore, DFT calculation was carried out for studying the structure-activity relationship (SAR). CONCLUSION: A practical synthetic route to obtain 1,2,4-triazolo[4,3-a]pyridine derivatives is presented. This study suggests that the 1,2,4-triazolo[4,3-a]pyridine derivatives exhibited good antifungal activity.
ABSTRACT
A series of novel carboxamide compounds 19a-19j, 20a-20j and 22a-22d containing piperazine and arylsulfonyl moieties have been synthesized. The bioassay results showed that some compounds exhibited favorable herbicidal activities against dicotyledonous plants and many of them possessed excellent antifungal activities. Among 24 novel compounds, some showed superiority over the commercial fungicides Chlorothalonil, Dimethomorph, Thiophanate-methyl, Iprodione, and Zhongshengmycin at 500 mg/L concentration. Some compounds also exhibited high KARI inhibitory activity at 100 µg/mL concentration and could be used as new KARI lead inhibitors for further studies. Moreover, SAR of these new compounds were comprehensively investigated using different computational methods in which 3D-QSAR model obtained provided useful information for further structural optimization for the discovery of new fungicides. The results of this research will contribute to explore comprehensive biological activities of piperazine-containing compounds in different areas of chemistry.
Subject(s)
Amides/chemical synthesis , Antifungal Agents/chemical synthesis , Herbicides/chemical synthesis , Quantitative Structure-Activity Relationship , Amides/pharmacology , Antifungal Agents/pharmacology , Arylsulfonic Acids/chemistry , Herbicides/pharmacology , Piperazine , Piperazines/chemistryABSTRACT
We reconstructed the first genome-scale metabolic network of the plant pathogen Pectobacterium carotovorum subsp. carotovorum PC1 based on its genomic sequence, annotation, and physiological data. Metabolic characteristics were analyzed using flux balance analysis (FBA), and the results were afterwards validated by phenotype microarray (PM) experiments. The reconstructed genome-scale metabolic model, iPC1209, contains 2235 reactions, 1113 metabolites and 1209 genes. We identified 19 potential bactericide targets through a comprehensive in silico gene-deletion study. Next, we performed virtual screening to identify candidate inhibitors for an important potential drug target, alkaline phosphatase, and experimentally verified that three lead compounds were able to inhibit both bacterial cell viability and the activity of alkaline phosphatase in vitro. This study illustrates a new strategy for the discovery of agricultural bactericides.
Subject(s)
Genome, Bacterial , Metabolic Networks and Pathways , Pectobacterium carotovorum/isolation & purification , Pectobacterium carotovorum/metabolism , Computer Simulation , Molecular Sequence Annotation , Pectobacterium carotovorum/genetics , Phenotype , Plant Diseases/genetics , Plant Diseases/microbiology , Plants/microbiologyABSTRACT
BACKGROUND: Maleimides, both natural and synthesised, have good biological activities. In a continuous effort to discover new maleimides with good antifungal activities, the authors have synthesised a series of 3,4-dichloro-, 3-methyl and non-substituted maleimides based on previous studies. The compounds were biologically evaluated against the fungal pathogen Sclerotinia sclorotiorum. RESULTS: Of the 63 compounds evaluated, 25 compounds had interesting inhibitory potency with EC50 < 10 µg mL(-1). N-(3,5-Dichlorophenyl)-3,4-dichloromaleimide (EC50 = 1.11 µg mL(-1)) and N-octyl-3-methylmaleimide (EC50 = 1.01 µg mL(-1)) were more potent than the commercial fungicide dicloran (EC50 = 1.72 µg mL(-1)). The results showed that compounds exhibiting log P values within the range 2.4-3.0 displayed the best results in terms of fungicidal activity, and this seemed, therefore, to be the optimum range for this physicochemical parameter. CONCLUSION: The present work demonstrates that some maleimides can be used as potential lead compounds for developing novel antifungal agents against S. sclerotiorum.
Subject(s)
Fungicides, Industrial/pharmacology , Maleimides/pharmacology , Antifungal Agents/chemical synthesis , Antifungal Agents/pharmacology , Ascomycota/drug effects , Fungicides, Industrial/chemical synthesis , Maleimides/chemical synthesis , Microbial Sensitivity Tests , Structure-Activity RelationshipABSTRACT
A novel series of 1,3,4-oxadiazole derivatives containing a 5-phenyl-2-furan moiety were synthesized from the intermediates diacylhydrazine 3 and acylhydrazone 5 via an efficient approach under microwave irradiation in good yields. Their structures were characterized by IR, (1)H NMR, and elemental analysis. The antifungal tests indicated that the title compounds showed in vivo fungicidal activity against Botrytis cinerea and Rhizoctonia solanii at 500 µg/mL obviously. Some tested compounds even had a superiority effect over the commercial fungicides 40% Pyrimethanil SC and 3% Validamycin AS. The activity between the title compound and their precursors diacylhydrazine 3 and acylhydrazone 5 was also compared and discussed.
Subject(s)
Fungicides, Industrial/chemical synthesis , Fungicides, Industrial/pharmacology , Oxadiazoles/chemical synthesis , Oxadiazoles/pharmacology , Botrytis/drug effects , Hydrazines/chemistry , Hydrazones/chemistry , Microwaves , Molecular Structure , Oxadiazoles/chemistry , Rhizoctonia/drug effectsABSTRACT
A series of novel pyrazole and triazole derivatives containing 5-phenyl-2-furan functionality were designed and synthesized. Their toxicities were predicted using in silico assays and proven to be less toxic. The antitumor results showed that the activity of compounds containing 1,3,4-triazole (series II) was higher than that of pyrazole-attached derivatives (series I). Among them, IIa and IIg showed much higher activity against Bel-7402 than doxorubicin. The fungicidal tests showed that most title compounds II exhibited great selectivity against Phytophthora capsici in vivo.