Interaction of dietary resveratrol with animal-associated bacteria

The recent decline in the effectiveness of some azole fungicides in controlling the wheat pathogen Mycosphaerella graminicola has been associated with mutations in the CYP51 gene encoding the azole target, the eburicol 14α-demethylase (CYP51), an essential enzyme of the ergosterol biosynthesis pathway. In this study, analysis of the sterol content of M. graminicola isolates carrying different variants of the CYP51 gene has revealed quantitative differences in sterol intermediates, particularly the CYP51 substrate eburicol. Together with CYP51 gene expression studies, these data suggest that mutations in the CYP51 gene impact on the activity of the CYP51 protein.     

Phenylpyrrole Fungicides: Mitotic Instability in Aspergillus nidulans and Resistance in Botrytis cinerea

The somatic recombinogenic activity of the phenylpyrrole fungicide fludioxonil, in diploid Aspergillus nidulans was found similar to that caused by aromatic hydrocarbon and dicarboximide fungicides (AHDFs), such as iprodione, chlozolinate and tolclofos–methyl. All these fungicides not only increased the number of mitotic recombinants but also provided similar appearance, small sectors, of white and yellow mitotic recombination products. Fludioxonil highly resistant strains (resistant factor approximately 5000) of Botrytis cinerea were isolated at high frequency (1.08 × 10⁻⁵). Study of cross-resistance patterns of mutant strains to other fungicides, revealed cross-resistance of fludioxonil with dicarboximides (iprodione, procymidone, and chlozolinate) and aromatic hydrocarbons, such as tolclofos–methyl, pentachloronitrobenzene (PCNB), tecnazene and chloroneb. The positive cross-resistance relationships found between phenylpyrroles and members of the AHDFs and their ability to increase mitotic instability in diploid A. nidulans , indicate that phenylpyrroles should be included with AHDFs. A study of fitness parameters in wild-type and representative fludioxonil-resistant mutants of B. cinerea , showed that the mutation(s) leading to fludioxonil resistance may or may not affect some fitness-determining characteristics, such as sensitivity to high osmolarity, growth rate, conidial germination and germ-tube elongation. Pathogenicity tests on cucumber seedlings showed that an osmosensitive representative strain of B. cinerea , resistant to fludioxonil, was as virulent as the wild-type strain. The phenylpyrrole fungicide was ineffective, even in high concentrations, to control grey mould caused by this isolate.     

Enhanced degradation of iprodione in soil after repeated treatments for controlling Sclerotinia minor

Poor field control of lettuce collar rot by iprodione was observed in southern France and was attributed to enhanced biodegradation of the fungicide. Enhanced biodegradation was obtained in vitro after repeated applications of iprodione to non-degrading soils. Normal soils became biodegrading after mixing with degrading soils (3 vol./1 vol.). Activity of the responsible microflora seemed dependent on soil physico-chemical characteristics.     

Triazole analog 1-(1-benzyl-5-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)-2-(4-bromophenylamino)-1-(4-chlorophenyl)ethanol induces reactive oxygen species and autophagy-dependent apoptosis in both in vitro and in vivo breast cancer models

Autophagy is considered as an important cell death mechanism that closely interacts with other common cell death programs like apoptosis. Critical role of autophagy in cell death makes it a promising, yet challenging therapeutic target for cancer. We identified a series of 1,2,3-triazole analogs having significant breast cancer inhibition property. Therefore, we attempted to study whether autophagy and apoptosis were involved in the process of cancer cell inhibition. The lead molecule, 1-(1-benzyl-5-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)-2-(4-bromophenylamino)-1-(4-chlorophenyl)ethanol (T-12) induced significant cell cycle arrest, mitochondrial membrane depolarization, apoptosis and autophagy in MCF-7 and MDA-MB-231 cells. T-12 increased reactive oxygen species and its inhibition by N-acetyl-l-cysteine protected breast cancer cells from autophagy and apoptosis. Autophagy inhibitor, 3-methyladenine abolished T-12 induced apoptosis, mitochondrial membrane depolarization and reactive oxygen species generation. This suggested that T-12 induced autophagy facilitated cell death rather than cell survival. Pan-caspase inhibition did not abrogate T-12 induced autophagy, suggesting that autophagy precedes apoptosis. In addition, T-12 inhibited cell survival pathway signaling proteins, Akt, mTOR and Erk1/2. T-12 also induced significant regression of tumor with oral dose of as low as 10 mg/kg bodyweight in rat mammary tumor model without any apparent toxicity. In presence of reactive oxygen species inhibitor (N-acetyl-l-cysteine) and autophagy inhibitor (chloroquine), T-12 induced tumor regression was significantly decreased. In conclusion, T-12 is a potent inducer of autophagy-dependent apoptosis in breast cancer cells both in vitro and in vivo and can serve as an important lead in development of new anti-tumor therapy.     

Can synthetic pesticides be replaced with biologically-based alternatives?—an industry perspective

Agricultural chemical companies have invested in the discovery and development of biological pesticides to complement synthetic pesticides for the control of insects, diseases, and weeds on agronomic and horticultural crops. For plant disease control, companies envisage biological fungicides entering markets where they have the best chance of performing and which are most receptive to using biological control methods. Fewer regulatory requirements can mean faster registration for a biological than a synthetic pesticide. However, industry’s requirements for competitive performance, effective formulations, and economic production can mean significant investments in time and money for a biological pesticide, although total investment may be less than for a synthetic pesticide. One biocontrol project in which industry has invested is baculoviruses for insect control. Insect baculoviruses, genetically modified to kill insects faster than wild-type viruses, are attractive biocontrol agents because their selectivity to insect pests and safety to beneficial insects and mammals enable them to compete with synthetic insecticides. Industry is looking for similar biocontrol opportunities in disease control. Biocontrol agents for seedling disease, root rot, and postharvest disease control have been registered by the EPA and are trying to compete with synthetic fungicides for market share. To date, effective biocontrol agents have not been identified for the control of serious foliar diseases, such as grape downy mildew, potato late blight, wheat powdery mildew, and apple scab. Farmers must rely on synthetic fungicides and agronomic methods to control these diseases for the foreseeable future. Received 06 February 1997/ Accepted in revised form 01 June 1997     

Detection of Colletotrichum spp. Resistant to Benomyl by Using Molecular Techniques

Colletotrichum species is known as the major causal pathogen of red pepper anthracnose in Korea and various groups of fungicides are registered for the management of the disease. However, the consistent use of fungicides has resulted in the development of resistance in many red pepper-growing areas of Korea. Effective management of the occurrence of fungicide resistance depends on constant monitoring and early detection. Thus, in this study, various methods such as agar dilution method (ADM), gene sequencing, allele-specific polymerase chain reaction (PCR), and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were applied for the detection of benzimidazole resistance among 24 isolates of Colletotrichum acutatum s. lat. and Colletotrichum gloeosporioides s. lat. The result of the ADM showed that C. gloeosporioides s. lat. was classified into sensitive and resistant isolates to benomyl while C. acutatum s. lat. was insensitive at ≥1 μg/ml of benomyl. The sequence analysis of the β-tubulin gene showed the presence of a single nucleotide mutation at the 198th amino acid position of five isolates (16CACY14, 16CAYY19, 15HN5, 15KJ1, and 16CAYY7) of C. gloeosporioides s. lat. Allele-specific PCR and PCR-RFLP were used to detect point mutation at 198th amino acid position and this was done within a day unlike ADM which usually takes more than one week and thus saving time and resources that are essential in the fungicide resistance management in the field. Therefore, the molecular techniques established in this study can warrant early detection of benzimidazole fungicide resistance for the adoption of management strategies that can prevent yield losses among farmers.     

Influence of N-fertilization and Fungicide Strategies on Fusarium Head Blight Severity and Mycotoxin Content in Winter Wheat

Nitrogen (N) fertilization and fungicide applications are still subject to discussion concerning the influence on Fusarium head blight (FHB) and related mycotoxin accumulation. Field studies were made in 2000–2001 and 2001–2002 to investigate the effect of two N‐rates and 11 plant protection treatments on FHB severity and the content of FHB‐related mycotoxins, namely deoxynivalenol (DON) and zearalenone (ZEA) under conditions of natural infection. The treatments applied can be summarized as (i) an integrated approach using a decision support system, (ii) the use of two plant strengtheners, Bion^® (benzo [1,2,3]thiadiazole‐7‐carbothioic acid S‐methyl‐ester, BTH) and a compound based on the biomass of the cyanobacterium Spirulina platensis, (iii) the use of plant strengtheners in combination with a broad‐spectrum fungicide and (iv) common fungicide strategies against foliar diseases. Fusarium infections as well as the analysed mycotoxins were observed at low levels in both years. Disease severity was significantly increased by conventional N‐fertilization only in 2001. Neither FHB severity nor mycotoxin accumulation was significantly influenced by any of the treatments, although treatments without fungicides appeared to lead to lower disease severities. In 2002, there was a tendency towards higher disease severities when common fungicide strategies were applied. Mycotoxin contamination was found in grain samples from both years. In 2001 DON was mainly traceable, whereas in 2002 ZEA was also detected. Mycotoxin contamination was influenced by N‐fertilization rather than by the treatments. In 2001, the DON content was significantly increased due to the conventional N‐supply. Our results indicate that less intensive fungicide strategies, including plant strengtheners, are no worse than common fungicide strategies under conditions of low FHB severity and mycotoxin accumulation. Immoderate N‐fertilization however, can increase mycotoxin levels significantly even under conditions unfavourable for Fusarium spp.     

Treatment with fungicides influences phytochemical quality of blackcurrant juice

The impact of fungicide treatment on fungal infection and blackcurrant juice quality was examined in a series of field experiments over the course of 2 years. Fungicide treatment reduced the incidence of foliar disease and resulted in changes in the concentration of sugars, organic acids, polyphenols and anthocyanins in blackcurrant juice. Treatment with Signum^® (containing pyraclostrobin, a strobilurin, and boscalid, a succinate dehydrogenase inhibitor) enhanced glucose, fructose and total sugar content in one treatment year but not in another. Treatment with Signum or Filan^® (containing boscalid only) caused a reduction in the key organic acid citrate. Treatment with Signum or Platoon^® (containing pyraclostrobin only) enhanced total polyphenol and anthocyanin content of juices. The data suggest a beneficial impact of fungicide treatment not only on disease control but also on juice phytochemistry.     

Effects of 20 fungicides on the infectivity of conidia of the aphid entomopathogenic fungus Erynia neoaphidis

The effect of 20 fungicides on theinfectivity of conidia of the entomopathogenicfungus, Erynia neoaphidis, were assessedin the laboratory. After projection on broadbean leaves, conidia were treated withfungicides applied at their recommended fieldrate. Afterwards, the infectivity of theseinocula was assessed using an aphid bioassay.Four fungicides, carbendazim, kresoxym-methyl, nuarimol and thiophanate-methyl reduced the infectivity of the conidia by less than 25% and can be considered harmless for this aphid pathogen. Propiconazole was a little more toxic, with 37% reduction. Other products reducedinfectivity by between 50% and 100%. These are, from the least to the most toxic:flutriafol, prochloraz, epoxyconazole,iprodione, hexaconazole, triadimenol,azoxystrobine, cyproconazole, cyprodynil,flusilazole and tridemorph. Chlorothalonil,fenpropimorph, spiroxamine and tebuconazoletotally inhibited infectivity of the fungi. Analysis of the results according to chemicalclass showed that the benzimidazoles were theleast toxic for E. neoaphidis and themorpholines the most toxic. Effects oftriazoles and strobilurines were variable, withreduction ranging from 37% to 100% fortriazoles and from 17% to 68% forstrobilurines.