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Plant pathogenic fungi pose a major threat to global food security, ecosystem services, and human livelihoods. Effective and broad-spectrum fungicides are needed to combat these pathogens. In this study, a novel antifungal 2-oxyacetate hydrazide quinoxaline scaffold as a simple analogue was designed and synthesized. Their antifungal activities were evaluated against Botrytis cinerea ( B. cinerea ), Altemaria solani ( A. solani ), Gibberella zeae ( G. zeae ), Rhizoctonia solani ( R. solani ), Colletotrichum orbiculare ( C. orbiculare ), and Alternaria alternata ( A. alternata ). These results demonstrated that most compounds exhibited remarkable inhibitory activities and possessed better efficacy than ridylbacterin, such as compound 15 (EC 50 = 0.87 μg/mL against G. zeae , EC 50 = 1.01 μg/mL against C. orbiculare ) and compound 1 (EC 50 = 1.54 μg/mL against A. alternata , EC 50 = 0.20 μg/mL against R. solani ). The 3D-QSAR analysis of quinoxaline-2-oxyacetate hydrazide derivatives has provided new insights into the design and optimization of novel antifungal drug molecules based on quinoxaline.

This study evaluates the antibacterial and antifungal activities of petroleum ether, acetic ether, n-butanol and aqueous extracts from Anoectochilus roxburghii. The in vitro antibacterial and antifungal effects against three bacterial strains (Escherichia coli, Bacillus subtilis, Bacillus thuringiensis) and three fungal species (Exserohilum turcicum (Pass.) Leonard et Suggs, Botrytis cinerea Pers., Fusahum graminearum Sehw.) were assayed by the dilution and disc-diffusion methods. All of the polar extracts expressed dose-dependent antimicrobial activity against all tested microorganisms. The most active extract was aqueous extract, with a minimum inhibitory concentration below 0.625mg/ml in both bacteria and fungi. The results suggest that new chemical classes of natural antimicrobial substances (such as A. roxiburghii extracts) can be selectively exploited for the chemotherapy and control of infectious diseases.

Five new polyphenolic derivatives, sepiumols A-E (1-5), were isolated from the root barks of Periploca sepium. Their structures were elucidated by interpretation of NMR spectroscopic and mass spectrometric data. Compounds 1, 3 and 5 were found to exhibit significant antifungal activity, particularly for 3 with the remarkable activity against Gibberella saubinetii and Alternaria longipes with MIC values of 1.56 and 3.13 μg/mL (ketoconazole: 0.78 μg/mL), respectively. In addition, compounds 1, 3 and 5 also displayed significant antibacterial activity against methicillin-resistant Staphylococcus aureu with MIC values of 12.50-25 μg/mL (ciprofloxacin: 0.78 μg/mL)., (Copyright © 2019. Published by Elsevier B.V.)

Diflumetorim is a member of pyrimidinamine fungicides that possess excellent antifungal activities. Nevertheless, as reported that the activity of diflumetorim to corn rust (Puccinia sorghi) was not ideal (EC 50  = 53.26 mg/L). Herein, a series of novel pyrimidinamine derivatives containing phenyl-thiazole/oxazole moiety were designed based on our previous study and the structural characteristics of diflumetorim, synthesized and bioassayed to discover novel fungicides with excellent antifungal activities. Among these compounds, T18 gave the optimal fungicidal activity, which respectively offers control effects with EC 50 values of 0.93 mg/L against P. sorghi and 1.24 mg/L against E. graminis, significantly superior to commercial fungicides diflumetorim, tebuconazole, and flusilazole. Cell cytotoxicity results suggested that compound T18 has lower toxicities than diflumetorim. Furthermore, DFT calculation indicated that the phenyl-thiazole/oxazole moiety plays an unarguable role in the improvement of activity, which will contribute to designing and developing more potent compounds in the future., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A series of novel Mannich base derivatives of flavone containing benzylamine moiety was synthesized using the Mannich reaction. The results of antifungal activity are not ideal, but its antifungal effect has a certain increase compared to flavonoids. After that, four bacteria were used to test antibacterial experiments of these compounds; compound 5g (MIC = 0.5, 0.125 mg/L) showed significant inhibitory activity against Staphylococcus aureus and Salmonella gallinarum compared with novobiocin (MIC = 2, 0.25 mg/L). Compound 5s exhibited broad spectrum antibacterial activity (MIC = 1, 0.5, 2, 0.05 mg/L) against four bacteria. The selected compounds 5g and 5s exhibit potent inhibition against Topo II and Topo IV with IC 50 values (0.25-16 mg/L). Molecular docking model showed that the compounds 5g and 5s can bind well to the target by interacting with amino acid residues. It will provide some valuable information for the commercial antibacterial agents.

In this paper, a series of 6-O-imidazole-based quaternary ammonium chitosan derivatives via 6-O-chloroacetyl chitosan (CAClC) were successfully designed and synthesized. Detailed structural characterization was carried out by means of FT-IR and 1 H NMR spectroscopy, and elemental analysis. Furthermore, the antioxidant property against hydroxyl radicals, superoxide radicals, and DPPH radicals was evaluated in vitro. 2-(N,N,N-trimethyl)-6-O-(2-aminobenzimidazole)acetyl chitosan chloride (2NPhMC) and 2-(N,N,N-trimethyl)-6-O-(1-butylimidazole)acetyl chitosan chloride (NBMC) showed more than 90% scavenging indices at 1.6 mg/mL. Besides, the antifungal activity against Botrytis cinerea and Gibberella zeae was estimated using in vitro MIC and hypha measurements. Most of the quaternized chitosan derivatives especially with the long length alkyl chain and primary amino group showed an inhibitory index of > 85% at 1.0 mg/mL against Botrytis cinerea. Besides, the cytotoxicity of chitosan and all the quaternized chitosan derivatives was evaluated in vitro on HaCaT cells and all the quaternized chitosan derivatives bearing 6-O-imidazole exhibited low cytotoxicity. These results suggested that chitosan derivatives bearing 6-O-imidazole-based quaternary ammonium salts may be used as good biomaterials., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

In this paper, a highly copper-resistant fungal strain NT-1 was characterized by morphological, physiological, biochemical, and molecular biological techniques. Physiological response to Cu(II) stress, effects of environmental factors on Cu(II) biosorption, as well as mechanisms of Cu(II) biosorption by strain NT-1 were also investigated in this study. The results showed that NT-1 belonged to the genus Gibberella, which exhibited high tolerance to both acidic conditions and Cu(II) contamination in the environment. High concentrations of copper stress inhibited the growth of NT-1 to various degrees, leading to the decreases in mycelial biomass and colony diameter, as well as changes in morphology. Under optimal conditions (initial copper concentration: 200 mg L -1 , temperature 28 °C, pH 5.0, and inoculum dose 10%), the maximum copper removal percentage from solution through culture of strain NT-1 within 5 days reached up to 45.5%. The biosorption of Cu(II) by NT-1 conformed to quasi-second-order kinetics and Langmuir isothermal adsorption model and was confirmed to be a monolayer adsorption process dominated by surface adsorption. The binding of NT-1 to Cu(II) was mainly achieved by forming polydentate complexes with carboxylate and amide group through covalent interactions and forming Cu-nitrogen-containing heterocyclic complexes via Cu(II)-π interaction. The results of this study provide a new fungal resource and key parameters influencing growth and copper removal capacity of the strain for developing an effective bioremediation strategy for copper-contaminated acidic orchard soils.

A novel type of O-carboxymethyl chitosan Schiff bases (O-CSPX) was synthesized via a condensation reaction. After the coordination reaction of cupric ions, zinc ions and nickel ions, metal complexes (O-CSPX-M) were achieved. The theoretical structure of O-CSPX-M calculated by Gaussian 09 reveals that the copper ions and nickel ions underwent dsp 2 hybridization, the zinc ions underwent sp 3 hybridization, and they all coordinated by the carbon atom in the p-π conjugate group. Then, the structures were confirmed by FT-IR, 1 H NMR, CP-MAS 13 C NMR, elemental analysis, DSC and XRD. The antifungal properties of O-CSPX-M against Phytophthora capsici (P. capsici), Gibberella zeae (G. zeae), Fusarium oxysporum (F. oxysporum) and Botrytis cinerea (B. cinerea) were evaluated at concentrations ranging from 0.05mg/mL to 0.40mg/mL. The experiments indicated that the derivatives have significantly enhanced antifungal activity after metal ions complexation compared with the original chitosan. Moreover, it was shown that 0.20mg/mL of O-CSPX-Cu can 100% inhibit the growth of P. capsici and 0.20mg/mL of O-CSPX-Ni can 87.5% inhibit the growth of B. cinerea. In addition, the phytotoxicity assay and cell viability assay were also evaluated. The experimental results may provide a novel direction for the development of metal fungicides., (Copyright © 2017. Published by Elsevier B.V.)

A novel type of O-carboxymethyl chitosan Schiff bases (O-CSPX) was synthesized via a condensation reaction. After the coordination reaction of cupric ions, Cu(II) complexes (O-CSPX-Cu) were achieved. The theoretical structure of O-CSPX-Cu calculated by Gaussian 09 reveals that the copper ions underwent dsp 2 hybridization, coordinated by the carbon atom in the p-π conjugate group and the oxygen atoms in the acetate ion. Then, the structures were confirmed by FT-IR, 1 H NMR, CP-MAS 13 C NMR, elemental analysis, DSC and XRD. The antifungal properties of O-CSPX-Cu against Phytophthora capsici (P. capsici), Gibberella zeae (G. zeae) and Glomerella cingulata (G. cingulata) were evaluated at concentrations ranging from 0.05mg/mL to 0.20mg/mL. The experiments indicated that the derivatives have significantly enhanced antifungal activity after copper ion complexation compared with the original chitosan. Moreover, it was shown that 0.20mg/mL of O-CSP3-Cu and O-CSP4-Cu can 100% inhibit the growth of P. capsici. The experimental results reveal that the antifungal efficiency is related to the space steric hindrance on the benzene ring, which may provide a novel direction for the development of copper fungicides., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In this study, three pyrimethanil grafted chitosan (PML-g-CS) derivatives were obtained. The structures of the conjugates were confirmed by FT-IR, (1)H NMR, and EA. The grafting ratios were measured by HPLC. Antifungal properties of pyrimethanil grafted chitosan (PML-g-CS) derivatives against the plant pathogenic fungi Rhizoctonia solani and Gibberella zeae were investigated at concentrations of 100, 200, and 400 mg/L. The PML-g-CS derivatives showed enhanced antifungal activity in comparison with chitosan. The PML-g-CS-1 showed the best antifungal activity against R. solani, whose antifungal index was 58.32%. The PML-g-CS-2 showed the best antifungal activity against G. zeae, whose antifungal index was 53.48%. The conjugation of chitosan and pyrimethanil showed synergistic effect. The PML-g-CS derivatives we developed showed potential for further study and application in crop protection.

In the present study, using chalcone as a lead compound, a series of its derivatives (compounds 1-30) were designed and synthesised. Their activity of anti-pathogenic fungi of plants has been evaluated. It is found that these compounds have good antifungal activity against Sclerotinia sclerotiorum, Helminthosprium maydis, Botrytis cinerea, Rhizoctonia solani and Gibberella zeae. Among them, the inhibition of growth for compound 30 against S. sclerotiorum showed 89.9%, with the median effective concentrations (EC50) of 15.4 μg mL(-1). The inhibition of growth for compounds 28, 29 and 30 at a concentration of 100 μg mL(-1) against H. maydis is 90.3%, 90.7% and 91.1%, with EC50 of 15.1, 18.3 and 18.1μg mL(-1), respectively.

Background: Carbendazim has been used in the control of Fusarium head blight (FHB) for more than 30 years in China. Thus, carbendazim-resistant (Car(R) ) populations of Gibberella zeae have developed in some areas. In this study, 9341 G. zeae isolates were collected from the ten main wheat-producing regions of China in the period from 2008 to 2012, and sensitivity to carbendazim was detected., Results: A high frequency of Car(R) isolates was observed in Zhejiang and Jiangsu provinces. Car(R) isolates were recovered from Anhui and Henan provinces in 2009 and 2012, respectively, but were not detected in the other six regions. Available (F167Y, E198Q and F200Y) and newly developed (E198L and E198K) allele-specific PCR assays were used to genotype field Car(R) isolates. The β-tubulin variants harbouring point mutation F167Y or E198Q accounted for >95% in Car(R) populations. Quantitative allele-specific real-time PCR assays were developed to determine the frequencies of five different β-tubulin variants present in populations of perithecia sampled from rice stubble., Conclusion: Car(R) populations of G. zeae develop rapidly under the selection pressure of carbendazim. Real-time PCR assays detecting the resistance frequencies in populations of perithecia would provide useful information for FHB control and management of resistance., (© 2013 Society of Chemical Industry.)

Seven known metabolites, dianhydro-aurasperone C (1), isoaurasperone A (2), fonsecinone A (3), asperpyrone A (4), asperazine (5), rubrofusarin B (6) and (R)-3-hydroxybutanonitrile (7), were isolated from the culture of Aspergillus sp. KJ-9, a fungal endophyte isolated from Melia azedarach and identified by spectroscopic methods. All isolates were evaluated in vitro against several phytopathogenic fungi (Gibberella saubinetti, Magnaporthe grisea, Botrytis cinerea, Colletotrichum gloeosporioides and Alternaria solani) and pathogenic bacteria (Escherichia coli, Bacillus subtilis, Staphyloccocus aureus and Bacillus cereus). Compounds 3 and 7 were active against almost all phytopathogenic fungi tested with minimum inhibitory concentration (MIC) range of 6.25-50 μM. Moreover, compound 3 was active against all pathogenic bacteria with MIC in the range of 25-100 μM. Compound 7 is a rare new natural product isolated from a natural source for the first time, and the detailed NMR data of 1 were first assigned.

Nine known metabolites, 6,8,1'-tri-O-methyl averantin (1), 6,8-di-O-methyl averufnin (2), 6,8-di-O-methyl averufanin (3), aversin (4), 1,3-dihydroxy-6,8-dimethoxy-9,10-anthraquinone (5), 6,8-di-O-methylnidurufin (6), 6,8-di-O-methyl versiconol (7), 5-methyoxysterigmatocystin (8) and (S)-ornidazole (9), were isolated from the extracts of Penicillium purpurogenum, and their structures were elucidated by using spectroscopic methods. The brine shrimp toxicity, anti-phytopathogenic and phytotoxic effects of these compounds were evaluated. Among them, compounds 1 and 8 exhibited the strongest toxicity against brine shrimp (Artemia salina), with lethality rates of 100% at a low concentration of 10 μM, comparable to the positive control toosendanin. Compounds 1, 4 and 7 moderately inhibited the growth of Botrytis cinerea. Moreover, 4 displayed moderate antifungal effects on Gibberella saubinettii. In addition, compounds 6, 7 and 9 produced the phytotoxic effects on radish seedlings at 100 μM. This is the first report on the isolation of these metabolites from this organism.

Two new α-pyrones (=2H-pyran-2-ones), ficipyrones A and B (1 and 2, resp.), and two new α-furanones (=2H-furan-2-ones), ficifuranones A and B (3 and 4, resp.), together with three known metabolites, antibiotic F 0368 (5), hydroxyseiridin (6), and hydroxyisoseiridin (7), were isolated from solid cultures of the plant endophytic fungus Pestalotiopsis fici. Their structures were elucidated primarily by NMR spectroscopy, and the absolute configuration of 1 was deduced from the circular-dichroism (CD) data. Compound 1 showed antifungal activity against the plant pathogen Gibberella zeae (CGMCC 3.2873) with an IC50 value of 15.9 μM., (Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.)

Twenty-seven novel (E)-3-[2-arylideneaminoethyl]-2-[4-(trifluoromethoxy)anilino]-4(3H)-quinazolinone derivatives were synthesized by reacting various aromatic aldehydes with intermediate 6. The target compounds were characterized by (1)H NMR, (3)C NMR, IR, and elemental analysis. Bioassay results revealed that some of the compounds have strong antifungal activities against six fungi ( Gibberella zeae , Fusarium oxysporum , Clematis mandshurica , Paralepetopsis sasakii , Phytophthora infestans , and Sclerotinia sclerotiorum ) and three bacteria ( Xanthomonas oryzae , tomato bacterial wilt, and tobacco bacterial wilt). Notably, these compounds exhibited the highest activity against tomato bacterial wilt and X. oryzae, with 50% effective concentration (EC50) values ranging from 45.96 to 93.31 μg/mL and from 20.09 to 21.33 μg/mL, respectively, which are superior to those of the commercial antibacterial agents thiodiazole-copper (99.80 μg/mL) and bismerthiazol (92.61 μg/mL). These results indicate that novel arylimine derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco bacterial wilt, tomato bacterial wilt, and X. oryzae. Evaluation of their bactericidal properties in field studies as well as the mechanisms underlying their enhanced antibacterial activity should be interesting topics for future investigations.

Background: Fusarium head blight caused by Gibberella zeae is an important disease of wheat and barley because it reduces grain yield and quality and results in the contamination of grain with mycotoxins. Recent studies have shown that carbendazim resistance in field strains of G. zeae is not caused by mutation of the β-tubulin gene (β₁ tub), which is the case with other filamentous fungi, but that fungicide resistance is greatly increased by deletion of β₁ tub. The aim of the present study was to clarify the function of β₁ tub and its role in carbendazim resistance in G. zeae by artificial gene operation., Results: Deletion of β₁ tub reduced vegetative growth and pathogenicity but increased asexual reproduction in G. zeae. All the mutants were more resistant to carbendazim than parent strains. A three-dimensional model of β₁ tub was constructed, and the possible carbendazim binding site was analysed., Conclusion: β₁ tub is not an essential gene in G. zeae, but it affects the sensitivity of the fungus to carbendazim., (Copyright © 2012 Society of Chemical Industry.)

Sclerotiorin 1, first isolated from Penicillium sclerotiorum, has weak antifungal activity and belongs to the azaphilone-type family of natural products. Several series of sclerotiorin analogues were designed and synthesized with the aim of discovering novel fungicides with improved activity. The syntheses involved two key steps, cycloisomerization and then oxidation, and used a simple and efficient Sonogashira cross-coupling reaction to construct the required functionalized precursor. With sclerotiorin as a control, the activities of the newly synthesized analogues were evaluated against seven fungal pathogens, and several promising candidates (compounds 3a₁, 3d₂, 3e₂, 3f₂ and 3k₂) with greater activity and simpler structures than sclerotiorin were discovered. In addition, preliminary structure-activity relationships were studied, which revealed that not only the chlorine or bromine substituent at the 5-position of the nucleus but also the phenyl group at the 3-position and the substituent pattern on it contributed crucially to the observed antifungal activity. Analogues with a methyl substituent at the 1-position have reduced levels of activity, while those with a free hydroxyl group in place of acetoxy at the quaternary center of the bicyclic ring system retain activity.

Sixteen novel pyrazole acyl thiourea derivatives 6 were synthesized from monomethylhydrazine (phenylhydrazine) and ethyl acetoacetate. The key 5-chloro-3-methyl-1-substituted-1H-pyrazole-4-carbonyl chloride intermediates 4 were first generated in four steps through cyclization, formylation, oxidation and acylation. Thess were then reacted with ammonium thiocyanate in the presence of PEG-400 to afford 5-chloro-3-methyl-1-substituted-1H-pyrazole-4-carbonyl isothiocyanates 5. Subsequent reaction with fluorinated aromatic amines resulted in the formation of the title compounds. The synthesized compound were unequivocally characterized by IR, ¹H-NMR, ¹³C-NMR and elemental analysis and some of the synthesized compounds displayed good antifungal activities against Gibberella zeae, Fusarium oxysporum, Cytospora mandshurica and anti-TMV activity in preliminary antifungal activity tests.

The objective of the study was to identify the lipopetides associated with three Bacillus subtilis strains. The strains are antagonists of Gibberella zeae, and have been shown to be effective in reducing Fusarium head blight in wheat. The lipopeptide profile of three B. subtilis strains (AS43.3, AS43.4, and OH131.1) was determined using mass spectroscopy. Strains AS43.3 and AS43.4 produced the anti-fungal lipopeptides from the iturin and fengycin family during the stationary growth phase. All three strains produced the lipopeptide surfactin at different growth times. Strain OH131.1 only produced surfactin under these conditions. The antifungal activity of the culture supernatant and individual lipopeptides was determined by the inhibition of G. zeae. Cell-free supernatant from strains AS43.3 and AS43.4 demonstrated strong antibiosis of G. zeae, while strain OH131.1 had no antibiosis activity. These results suggest a different mechanism of antagonism for strain OH131.1, relative to AS43.3 and AS43.4.

Background: The efficacy of benzimidazole fungicides is often limited by resistance, and this is the case with the use of carbendazim for controlling Fusarium head blight caused by Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum). Recent studies have shown that carbendazim resistance in field strains of G. zeae is associated with mutations in the β(2)-tubulin gene. The aims of the present study were to validate this mechanism and research the binding sites of carbendazim on β(2)-tubulin., Results: This work used site-directed mutagenesis followed by gene replacement to change the β(2)-tubulin gene of a carbendazim-sensitive field strain of G. zeae at residues 50, 167, 198 or 200. The transformants were confirmed and tested for their sensitivity to carbendazim. All the mutants were resistant to carbendazim, but the level of resistance differed depending on the mutation. Biological characteristics did not differ between the field strain and the site-directed mutants. A three-dimensional model of β(2)-tubulin was constructed, and the possible carbendazim binding site was analysed., Conclusion: Mutations at codons 50, 167, 198 and 200 of G. zeae β(2)tub could cause resistance to carbendazim, and these codons may form a binding pocket., (Copyright © 2010 Society of Chemical Industry.)

ABSTRACT Wheat head blight caused by Gibberella zeae (anamorph: Fusarium graminearum) is a threat to food safety in China because of mycotoxin contamination of the harvested grain, the frequent occurrence of the disease, and the failure of chemical control in some areas due to benzimidazole resistance in the pathogen population. The molecular resistance mechanism, however, of G. zeae to benzimidazole fungicides (especially carbendazim; active ingredient: methyl benzimidazol-2-yl carbamate [MBC]) is poorly understood. DNA sequences of a beta-tubulin gene (beta(2)tub) (GenBank access number FG06611.1) in G. zeae were analyzed. Mutations in beta(2)tub in moderately resistant strains (MBC(MR)) included TTT (Phe)-->TAT (Tyr) at codon 167 or TTC (Phe)-->TAC (Tyr) at codon 200. A highly resistant strain (MBC(HR)) had two point mutations, one at codon 73, CAG (Gln)-->CGG (Arg), and the other at codon 198, GAG (Glu)-->CTG (Leu). To confirm that mutations in the beta(2)tub confer resistance to benzimidazole fungicides, the entire beta(2)tub locus was deleted from MBC(MR) and MBC(HR) strains of G. zeae. The resulting Deltabeta(2)tub mutants from both MBC(MR) and MBC(HR) strains grew normally on MBC-free potato dextrose agar medium and were supersensitive to MBC. Complementation of the Deltabeta(2)tub mutants by transformation with a copy of the intact beta(2)tub locus from their parent strains exhibited less resistance than the original strains, and complementation of the Deltabeta(2)tub mutants by transformation with a copy of the intact beta(2)tub locus from sensitive strains restored MBC sensitivity. The results indicated that the mutations in the beta(2)tub gene conferred resistance of G. zeae to benzimidazole fungicides and this gene can be used as a genetic marker in G. zeae.

The methanolic extract of the fruiting bodies of the mushroom Armillariella tabescens was found to show antifungal activity against Gibberella zeae. The active compound was isolated from the fruiting bodies of A. tabescens by bioassay-guided fractionation of the extract and identified as armillarisin B. Armillarisin B eventually corresponds to 2-hydroxy-2-phenylpropanediamide and its structure was confirmed on the basis of spectroscopic studies including 2D NMR experiments.

A series of novel analogues of pyrrolnitrin containing a thiophene moiety were designed and synthesized by a facile method, and their structures were characterized by (1)H nuclear magnetic resonance (NMR) and high-resolution mass spectrometry. The isomers IV-h and V-h were isolated, and their structures were identified by 2D NMR, including heteronuclear multiple-quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC), and nuclear Overhauser effect spectrometry (NOESY) spectra. Their fungicidal activities against five fungi were evaluated, and the results indicated that some of the title compounds showed excellent fungicidal activities in vitro against Alternaria solani , Gibberella zeae , Physalospora piricola , Fusarium omysporum , and Cercospora arachidicola at the dosage of 50 microg mL(-1). Some compounds shown moderate activity at low dosage. Compound V-h could be considered as a leading structure for further design of agricultural fungicides.

Strain MY75 is a gram-positive, aerobic, endospore-forming bacterium that can secrete high levels of extracellular chitinase (4.645 U/ml) when chitin powder exists as an inducer. This strain was identified as Bacillus licheniformis using the Biolog MicroLog microbial identification system and sequence analysis of 16S rDNA, gyrA and rpoB genes. Strain MY75 has the ability to inhibit the growth of Gibberella saubinetii and Aspergillus niger, two major pathogenic fungi in agriculture, and to restrain their spore germination completely. The chitinase was proved to play an important role in the strain's antifungal activity.

Pestalachlorides A-C (1-3), three new chlorinated benzophenone derivatives, have been isolated from cultures of an isolate of the plant endophytic fungus Pestalotiopsis adusta. The structures of these compounds were determined mainly by NMR spectroscopy, and the structures of 1 and 3 were further confirmed by X-ray crystallography. Pestalachloride A (1) was obtained as a mixture of two inseparable atropisomers (1a and 1b), whereas pestalachloride C (3) was found to be a racemic mixture. Compounds 1 and 2 displayed significant antifungal activities against three plant pathogens.

A simple, efficient, and general method has been developed for the synthesis of various 3-alkylquinazolin-4-one derivatives from quinazolin-4-one treated with alkyl bromides under phase transfer catalysis condition. The structures of the compounds were characterized by elemental analysis, IR, (1)H-NMR and (13)C-NMR spectra. Title compound 6-bromo-3-propylquinazolin-4-one (3h) was found to possess good antifungal activity.

Bacillus subtilis JA antagonized the growth of Gibberella zeae. In order to reduce growth of this fungi pathogen to a greater extent, low-energy ion beam implantation was applied in mutant breeding. We studied the effects of different energies and different doses of nitrogen ion implantation. The mutant strain designated as JA026 was obtained showing higher inhibition activity in the screening plate. Its inhibition zone against indicator organism increased by 14.3% compared to the original strain. The electrospray ionization mass spectrometry (ESI/MS) analysis indicated that the antifungal lipopeptides produced by the mutant were identical to those produced by the wild-type strain. The mutant strain exhibited favorable properties including the high yield of antifungal lipopeptides production and faster growth over the parent strain, which suggested that this strain would be a promising biocontrol candidate in agriculture.

A series of 2-oxocycloalkylsulfonylureas (2) have been synthesized in a six-step, three-pot reaction sequence from readily available cyclododecanone, cycloheptanone, and cyclohexanone. Their structures were confirmed by IR, 1H NMR, and elemental analysis. The bioassay indicated that some of them possess certain fungicidal activity against Gibberella zeae Petch. In general, compounds containing a 12-membered ring (2A) are more active than those containing a 6- or 7-membered ring (2B, 2C). In the series 2A, the compounds in which R is a disubstituted phenyl or pyrimidyl showed better activity than those in which R is a monosubstituted phenyl or pyrimidyl, and aryl-substituted compounds have somewhat higher activity than those substituted by pyrimidyl. The further bioassay showed that the representative of 2A, 2A15, has good fungicidal activities against not only G. zeae Petch but also Botrytis cinerea Pers, Colletotrichum orbiculare Arx, Pythium aphanidermatum Fitzp, Fusarium oxysporum Schl. f. sp. Vasinfectum, etc.

The importance of six theoretically calculated molecular parameters in the antigibberellin (retardant) activity of quaternary ammonium salts is studied using regression analysis. A bioassay system based on cell culture of fungus Gibberella fujikuroi is used to determine the activity. In the case of N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium chloride (choline) and N,N,N-triethyl-N-(2-hydroxyethyl)ammonium chloride (N,N,N-triethylcholine) derivatives with linear structure, the polarizability, proton acceptor activity, and lipophilicity of these compounds exert the largest effect on the antigibberellin activity. The antigibberellin activity of more sterically hindered N,N-dialkylpiperidinium salts was mainly defined by the steric parameter, while the polarizability, proton acceptor activity, and (through them) lipophilicity exert a lesser effect. Other parameters are of minor importance for the three groups of compounds studied. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.

The mutants of wild-type Gibberella zeae resistance to carbendazim were generated in laboratory by ultra-violet (UV) irradiating and fungicide taming. Two levels of resistance (low, LR; high, HR) were identified among these mutants. LR mutants could grow at the critical concentration of 1.4 +/- microg/mL of carbendazim while completely inhibited above 10 microg/ mL concentration, but this phenotype of isolates was not detected in the field. HR mutants could grow at 100 microg/mL and showed negative cross-resistance with N-phenylcarbamate fungicides, such as N-( 3,5-dichlorophenyl) carbamate (MDPC) whereas the LR mutants were not. Moderate resistant (MR) mutants which could grow fast at 10 microg/mL, but completely inhibited at 100 microg/mL, were not generated in laboratory. HR mutants of field MR isolate were also generated by fungicide taming on 100 microg/mL of carbendazim, but these mutants did not express negative cross-resistance to MDPC. The genetic study suggested that the carbendazim-resistance in these mutants could be steadily inherited by asexual and selfed reproduction, and the resistance was controlled by the same single major gene both in laboratory mutants and field resistant isolates, the different levels of resistance or the same resistant level in different strains maybe conferred by mutations at different sites or one site with different allelic mutations. The gene compensates for the sensitivity to MDPC was allelic to that governs the carbendazim resistance, but the mutation for increasing sensitivity to MDPC in this gene could get the pathogen highly resistant to carbendazim.

Whole beta-tubulin genes from wild carbendazim(MBC)-sensitive isolate, field MBC-resistant isolate and induced MBC-resistant mutant of Gibberella zeae were cloned and sequenced with 3 pairs of primers. These genes have 1631bp length, including 3 introns, encoding 447 amino acid. The homology of amino acid tubulin gene of G. zeae with that of other common plant pathogenic filamentous fungi is from 95.12% approximately 99.30%. Sequence comparison among MBCs, field MBCR and induced MBCR isolates revealed there was no mutation, even one. So it can be concluded that the mechanism of MBC-resistance to G. zeae is different from other filamentous fungi caused by point mutation at amino acid position 198 or other position of beta-tubulin gene.

According to the ability of the field isolates of Gibberella zeae to grow on the PSA with varying carbendazim(MBC) concentrations, three sensitivity levels of isolates were determined in vitro. The sensitive isolates(S) could grow at 0.5 microgram/ml, but were completely inhibited at 1.4 micrograms/ml. The moderate resistant isolates (MR) could grow fast at 1.4 micrograms/ml and slow at 50 micrograms/ml, but could not grow at 100 micrograms/ml. The high resistant isolates(HR) could grow faster than R at 50 micrograms/ml, and also could grow at 100 micrograms/ml. No low resistant isolates, that could grow fast at 1.4 micrograms/ml but could not grow at 50 micrograms/ml, were found among the field isolates. The genetics of resistance to carbendazim in G. zeae was investigated by analyzing the sensitivity of sexual outcrossed progeny to MBC. The nitrate non-utilizing mutant (nit) as an another added genetic marker was used to select the out-crossed perithecium from self-crossed perithecia. Seven crosses were tested in all, including cross between S x S, MR x S, MR x MR, HR x S, as well as HR x MR. The results showed that no recombinant phenotype was found among all progeny of seven crosses. Progeny segregation of crosses between the parents with different sensitive levels(i.e. MR x S, HR x S, HR x MR) clearly fit a 1:1 ratio of two parental phenotypes, and no segregation was found in the crosses of S x S and MR x MR. So it can be concluded that the two levels of MBC resistance in G. zeae are conferred by two loci mutations or one locus with different allelic mutations that constitute a polymorphic series in a single Mendelian gene. In these isolates, the MBC resistance is not affected by modifying genes or cytoplasmic components.

Two antifungal peptides, named EAFP1 and EAFP2, have been purified from the bark of Eucommia ulmoides Oliv. Each of the sequences consists of 41 residues with a N-terminal blockage by pyroglutamic acid determined by automated Edman degradation in combination with the tandem mass spectroscopy and the C-terminal ladder sequencing analysis. The primary structurs all contain 10 cysteines, which are cross-linked to form five disulfide bridges with a pairing pattern (C1-C5, C2-C9, C3-C6, C4-C7, C8-C10). This is the first finding of a plant antifungal peptide with a five-disulfide motif. EAFP1 and EAFP2 show characteristics of hevein domain and exhibit chitin-binding properties similar to the previously identified hevein-like peptides. They exhibit relatively broad spectra of antifungal activities against eight pathogenic fungi from cotton, wheat, potato, tomato and tobacco. The inhibition activity of EAFP1 and EAFP2 can be effective on both chitin-containing and chitin-free fungi. The values of IC(50) range from 35 to 155 microg/ml for EAFP1 and 18 to 109 microg/ml for EAFP2. Their antifungal effects are strongly antagonized by calcium ions.

Sterols, carotenoids and gibberellins are synthesized after the reduction of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) to mevalonate in different subcellular compartments of the fungus Gibberella fujikuroi. Lovastatin inhibits growth in many organisms, presumably because of the inhibition of the synthesis of essential terpenoids. However, in G. fujikuroi growth of the mycelia and sterol and carotenoid content were not affected by the presence of lovastatin. Nevertheless, lovastatin did inhibit the accumulation of gibberellins in the culture medium; this inhibition, however, was counteracted by the addition of mevalonate to the medium. The conversion of HMG-CoA to mevalonate in cell-free extracts was inhibited by 10 nM lovastatin. Since G. fujikuroi apparently possesses a single gene for HMG-CoA reductase, as shown by Southern hybridization and PCR amplification, it was concluded that the biosynthesis of sterols, carotenoids and gibberellins shares a single HMG-CoA reductase, but the respective subcellular compartments are differentially accessible to lovastatin.

Fumonisins are a group of structurally related mycotoxins produced by Gibberella fujikuroi. The fungus produced fumonisin B1 (FB1) as early as 18 hour in a defined medium containing 1.25 mM or 2.5 mM ammonium phosphate, whereas fumonisin B1 production was repressed for 75 hour and 125 hour when mycelia were resuspended in media containing ammonium phosphate at 10 mM or 20 mM, respectively. Although total fumonisin B1 production was greater in resuspension cultures grown in higher concentrations of ammonium phosphate, the accumulation was independent of the inoculum size and carbon/nitrogen ratio. The addition of ammonium phosphate to cracked corn cultures also repressed fumonisin B1 production by 97%, and persisted for at least three weeks. Thus, biosynthesis of fumonisin B1 is regulated by a mechanism involving nitrogen metabolite repression, suggesting that control strategies that target the regulatory elements of nitrogen metabolism may be effective at reducing the risk of fumonisin contamination in food.

Gibberella pulicaris, a causal agent of potato dry rot, infects potato tubers via wounds, where it is exposed to the phytoalexins rishitin and lubimin. Incubation of mycelium on agar supplemented with phytoalexins transiently induced the transcription of a polyubiquitin gene consisting of four ubiquitin units arranged head to tail; the fourth unit contains a 54-bp intron and an additional glutamine at the C-terminus of the encoded protein. Southern analysis of the G. pulicaris genome revealed one copy of the isolated polyubiquitin gene and one or two copies of other ubiquitin genes. Increased transcription of the gene was detectable above a threshold of 100 microg/ml of rishitin and at elevated temperatures, which indicates that exposure to phytoalexins causes a stress reaction of hyphal cells similar to that after heat shock.

Gibberellin production in Gibberella fujikuroi starts upon exhaustion of the nitrogen source. To determine the role of nitrate and ammonium in the regulation of gibberellin biosynthesis we have isolated mutants that cannot use nitrate as a nitrogen source. Nitrate inhibited partially the production of gibberellins in mutants devoid of nitrate reductase activity. The inhibition occurred whether nitrate was added before or after the onset of gibberellin production. Addition of tungstate to the wild type mimicked the results with nitrate reductase mutants. We conclude that nitrate inhibits gibberellin biosynthesis by itself, independently of the intracellular signal that conveys nitrogen availability.

The gibberellin (GA) biosynthetic pathway includes four apparent cytochrome P450-mediated steps that convert kaurene to 7 alpha-hydroxykaurenoic acid. One of these reactions, the hydroxylation of kaurenoic acid to 7 alpha-hydroxykaurenoic acid, is mediated by kaurenoic acid hydroxylase. This reaction can be catalyzed in vitro by microsomal preparations from the fungus Gibberella fujikuroi (Saw.) Wr. and monitored by HPLC. Cultures grown in the presence of 84 microM AMO-1618 (an inhibitor of kaurene synthesis) had reduced levels of GA3 in fungal filtrates and decreased cell-free kaurenoic acid hydroxylase activity. However, the level of hydroxylase activity from AMO-1618-treated cultures could be induced several-fold by growing cultures in the presence of 350 microM kaurene. Since transcripts related to GA biosynthesis might be decreased in AMO-1618-treated cultures, a subtractive hybridization procedure was used to enrich cDNA fragments corresponding to messages that are more abundant in untreated than treated cultures. A fungal cDNA library was screened with the subtraction products and a clone was isolated that corresponds to two down-regulated transcripts in AMO-1618-treated cultures. This cDNA does not encode a cytochrome P450 but may be associated with GA biosynthesis.

N-methyl-N'-nitro-N-nitrosoguanidine (nitrosoguanidine) and to a lesser extent UV radiation are very mutagenic for Gibberella microconidia. The recommended nitrosoguanidine doses lead to much higher frequencies of mutants than are found in other microorganisms. The frequency of mutants among the survivors increases linearly with the nitrosoguanidine dose (molar concentration X time); the absolute number of viable mutants in a given population reaches a maximum for a dose of ca. 0.7 M X s. The microconidia are uninucleate. The onset of germination brings about increased lethality of nitrosoguanidine, but it does not modify the action of UV radiation. Mycelia are more resistant than spores to both agents. Visible illumination effectively prevents lethality when given immediately after UV radiation. Auxotrophs and color mutants are very easily obtained. Pink adenine auxotrophs and several classes of color mutants are affected in the biosynthesis of the carotenoid pigment, neurosporaxanthin.