Re-discovery of MS-347a as a fungicide candidate through a new drug discovery platform with a multidrug-sensitive Saccharomyces cerevisiae screening system and the introduction of a global secondary metabolism regulator, laeA gene.

We found that the culture broth of fungi showed anti-fungal activity against multidrug-sensitive budding yeast. However, we could not identify the anti-fungal compound due to the small quantity. Therefore, we attempted to increase the productivity of the target compound by the introduction of a global secondary metabolism regulator, laeA to the strain, which led to the successful isolation of ten-folds greater amount of MS-347a (1) than Aspergillus sp. FKI-5362. Compound 1 was not effective against Candida albicans and the detailed anti-fungal activity of 1 remains unverified. After our anti-fungal activity screening, 1 was found to inhibit the growth of broad plant pathogenic fungal species belonging to the Ascomycota. It is noteworthy that 1 showed little insecticidal activity against silkworms, suggesting its selective biological activity against plant pathogenic fungi. Our study implies that the combination strategy of multidrug-sensitive yeast and the introduction of laeA is useful for new anti-fungal drug discovery.

Characterizing the Palm Pathogenic Thielaviopsis Species from Florida.

Thielaviopsis paradoxa sensu lato is a soilborne fungal pathogen that causes Thielaviopsis trunk rot and heart rot in palms. The loss of structural integrity resulting from trunk rot can cause the palm trunk to collapse suddenly and poses a serious threat to life and property. Even though rudimentary knowledge about the Thielaviopsis infection process in palms is available, nothing is known about the T. paradoxa species complex in the US. The aim of this study was to characterize T. paradoxa s. lat. isolates collected from diseased palms grown in Florida. Multi-locus phylogeny using three genes, ITS, ß-tubulin, and tef1-α, revealed that the isolates separate into two distinct clades with high bootstrap support. The majority of the isolates clustered with the species T. ethacetica, while two isolates formed a separate clade, distinct from T. musarum, and might represent an undescribed Thielaviopsis species. One representative isolate from each clade, when grown on three distinct media and at four different temperatures, showed differences in gross colony morphology, as well as growth rates. The T. ethacetica isolate TP5448 and the Thielaviopsis sp. isolate PLM300 grew better at opposite ends of the temperature spectrum tested in this study, i.e., 35 °C and 10 °C, respectively. In pathogenicity assays on whole plants, the T. ethacetica isolate proved to be more aggressive than Thielaviopsis sp. isolate PLM300, as it produced larger lesions when inoculated on wounded leaflets. An unequal distribution was observed for the mating-type locus of T. ethacetica, as 12 isolates carried the MAT1-1-1 allele, while the status for four isolates remained undefined. Variation in mycelial growth in response to different fungicides was also observed between the two clades. These results demonstrate the existence of two Thielaviopsis clades that can infect palms in Florida and underscore the need for targeted sampling to help uncover the diversity of Thielaviopsis species across palm-growing regions in the US.

Fungicide Sensitivity Profile of Pyrenophora teres f. teres in Field Population.

Pyrenophora teres f. teres (Ptt) is a severe pathogen to spring barley in Northern Europe. Ptt with relevant mutations in fungicide target proteins, sterol 14α-demethylase (CYP51A), cytochrome b (Cyt b), and succinate dehydrogenase (SDH) would put efficient disease control at risk. In the growing seasons of 2021 and 2022, 193 Ptt isolates from Estonia were analysed. In this study, mutation detection and in vitro fungicide sensitivity assays of single-spore isolates were carried out. Reduced sensitivity phenotype to mefentrifluconazole was evident in Ptt isolates with a F489L mutation in CYP51A or with 129 bp insert in the Cyp51A gene-promoter region. However, sensitivity to a prothioconazole-desthio remained high regardless of these molecular changes. The Ptt population was mostly sensitive to bixafen, fluxapyroxad, pyraclostrobin, and azoxystrobin. The sensitivity of fluxapyroxad and bixafen has been affected by two mutations, C-S135R and D-H134R, found in SDH subunits. The F129L mutation in Cyt b influenced azoxystrobin but not pyraclostrobin sensitivity. In total, 30 isolates from five fields had relevant mutations in three target protein genes simultaneously. Most of these isolates had a reduced sensitivity phenotype to mefentrifluconazole, fluxapyroxad, and azoxystrobin, while sensitivity to other tested fungicides remained high. Furthermore, possible sexual reproduction may enhance the pathogen's fitness and help it adapt to fungicides.

Novel litchi-like Au-Ag nanospheres driven dual-readout lateral flow immunoassay for sensitive detection of pyrimethanil.

Pyrimethanil (PYR) is a fungicide that is harmful to consumers when present in foods at concentrations greater than maximum permitted residue levels. High-performance immunoprobes and dual-readout strategy may be useful for constructing sensitive lateral flow immunoassay (LFIA). Herein, the prepared litchi-like Au-Ag bimetallic nanospheres (LBNPs) exhibited high mass extinction coefficients and fluorescence quenching constants. Benefiting from LBNPs and dual-readout mode, the limits of detection of LBNPs-CM-LFIA and LBNPs-FQ-LFIA for PYR were 0.957 and 0.713 ng mL-1, which were 2.54- and 3.41-fold lower than that of gold nanoparticles-based LFIA, respectively. The limits of quantitation of LBNPs-CM-LFIA and LBNPs-FQ-LFIA were 3.740 and 1.672 ng mL-1, respectively. LBNPs-LFIA was applied to detect PYR in cucumber and grape samples with satisfactory recovery (90%-111%). LBNPs-LFIA showed good agreement with LC-MS/MS for the detection of PYR in the samples. Accordingly, this sensitive and accurate dual-readout LFIA based on LBNPs can be effectively applied for food safety.

A Case of Severely Impaired Consciousness and Convulsions From Attempted Suicide by Ingesting Triflumizole Emulsion: Clinical Features and Literature Review.

Triflumizole (TFZ) is a fungicide widely used in agriculture to prevent fungal infections of fruits and vegetables. Although it is considered safe for humans and animals, its toxicity profile in humans remains largely unexplored. Here, we describe a case where an individual experienced symptoms suggestive of intoxication after ingesting TFZ emulsion. A 70-year-old man ingested TFZ emulsion (Trifumin emulsionTM) and alcohol in an attempt to commit suicide. He developed a severe disturbance of consciousness, which was not explained by the estimated blood alcohol concentration, and experienced convulsions. We managed this patient with symptomatic treatment, temporary mechanical ventilation, and antiepileptic drugs. He subsequently recovered without any sequelae. We present the first case of acute oral intoxication with TFZ emulsion. Moreover, we review the literature on TFZ-induced organ dysfunction and discuss the possible mechanisms and management of this condition.

Isolation of Streptomyces inhibiting multiple-phytopathogenic fungi and characterization of lucensomycin biosynthetic gene cluster.

Soil microorganisms with diverse bioactive compounds such as Streptomyces are appreciated as valuable resources for the discovery of eco-friendly fungicides. This study isolated a novel Streptomyces from soil samples collected in the organic green tea fields in South Korea. The isolation process involved antifungal activity screening around 2400 culture extracts, revealing a strain designated as S. collinus Inha504 with remarkable antifungal activity against diverse phytopathogenic fungi. S. collinus Inha504 not only inhibited seven phytopathogenic fungi including Fusarium oxysporum and Aspergillus niger in bioassays and but also showed a control effect against F. oxysporum infected red pepper, strawberry, and tomato in the in vivo pot test. Genome mining of S. collinus Inha504 revealed the presence of the biosynthetic gene cluster (BGC) in the chromosome encoding a polyene macrolide which is highly homologous to the lucensomycin (LCM), a compound known for effective in crop disease control. Through genetic confirmation and bioassays, the antifungal activity of S. collinus Inha504 was attributed to the presence of LCM BGC in the chromosome. These results could serve as an effective strategy to select novel Streptomyces strains with valuable biological activity through bioassay-based screening and identify biosynthetic gene clusters responsible for the metabolites using genome mining approach.

Azole resistance mechanisms and population structure of the human pathogen Aspergillus fumigatus on retail plant products.

Aspergillus fumigatus is a ubiquitous saprotroph and human-pathogenic fungus that is life-threatening to the immunocompromised. Triazole-resistant A. fumigatus was found in patients without prior treatment with azoles, leading researchers to conclude that resistance had developed in agricultural environments where azoles are used against plant pathogens. Previous studies have documented azole-resistant A. fumigatus across agricultural environments, but few have looked at retail plant products. Our objectives were to determine if azole-resistant A. fumigatus is prevalent in retail plant products produced in the United States (U.S.), as well as to identify the resistance mechanism(s) and population genetic structure of these isolates. Five hundred twenty-five isolates were collected from retail plant products and screened for azole resistance. Twenty-four isolates collected from compost, soil, flower bulbs, and raw peanuts were pan-azole resistant. These isolates had the TR34/L98H, TR46/Y121F/T289A, G448S, and H147Y cyp51A alleles, all known to underly pan-azole resistance, as well as WT alleles, suggesting that non-cyp51A mechanisms contribute to pan-azole resistance in these isolates. Minimum spanning networks showed two lineages containing isolates with TR alleles or the F46Y/M172V/E427K allele, and discriminant analysis of principle components identified three primary clusters. This is consistent with previous studies detecting three clades of A. fumigatus and identifying pan-azole-resistant isolates with TR alleles in a single clade. We found pan-azole resistance in U.S. retail plant products, particularly compost and flower bulbs, which indicates a risk of exposure to these products for susceptible populations and that highly resistant isolates are likely distributed worldwide on these products.IMPORTANCEAspergillus fumigatus has recently been designated as a critical fungal pathogen by the World Health Organization. It is most deadly to people with compromised immune systems, and with the emergence of antifungal resistance to multiple azole drugs, this disease carries a nearly 100% fatality rate without treatment or if isolates are resistant to the drugs used to treat the disease. It is important to determine the relatedness and origins of resistant A. fumigatus isolates in the environment, including plant-based retail products, so that factors promoting the development and propagation of resistant isolates can be identified.

Early life stage exposure to fenbuconazole causes multigenerational cardiac developmental defects in zebrafish and potential reasons.

With the increasing use of triazole fungicides in agriculture, triazole pesticides have aroused great concern about their toxicity and ecological risk. The current study investigated the impairments of embryonic exposure to fenbuconazole (FBZ) on cardiac transgenerational toxicity and related mechanisms. The fertilized eggs were exposed to 5, 50 and 500 ng/L FBZ for 72 h, and the larvae were then raised to adulthood in clean water. The adult fish were mated with unexposed fish to produce maternal and paternal F1 and F2 embryos, respectively. The results showed that increased arrhythmia were observed in F0, F1 and F2 larvae. Transcriptome sequencing indicated that the pathway of adrenergic signaling in cardiomyocytes was enriched in F0 and F2 larvae. In both F0 and F1 adult zebrafish hearts, ADRB2 protein expression decreased, and transcription of genes related to cardiac development and Ca2+ homeostasis was downregulated. These alterations might cause cardiac developmental defects. Significantly decreased protein levels of H3K9Ac and H3K14Ac might be linked with the downregulation in transcription of cardiac development genes. Protein‒protein interaction analysis exhibited that the pathway affecting the heart was well inherited in the paternal line. These results provide new ideas for the analysis and prevention of congenital heart disease.

Modes of action and potential as a peptide-based biofungicide of a plant defensin MtDef4.

Due to rapidly emerging resistance to single-site fungicides in fungal pathogens of plants, there is a burgeoning need for safe and multisite fungicides. Plant antifungal peptides with multisite modes of action (MoA) have potential as bioinspired fungicides. Medicago truncatula defensin MtDef4 was previously reported to exhibit potent antifungal activity against fungal pathogens. Its MoA involves plasma membrane disruption and binding to intracellular targets. However, specific biochemical processes inhibited by this defensin and causing cell death have not been determined. Here, we show that MtDef4 exhibited potent antifungal activity against Botrytis cinerea. It induced severe plasma membrane and organelle irregularities in the germlings of this pathogen. It bound to fungal ribosomes and inhibited protein translation in vitro. A MtDef4 variant lacking antifungal activity exhibited greatly reduced protein translation inhibitory activity. A cation-tolerant MtDef4 variant was generated that bound to ß-glucan of the fungal cell wall with higher affinity than MtDef4. It also conferred a greater reduction in the grey mould disease symptoms than MtDef4 when applied exogenously on Nicotiana benthamiana plants, tomato fruits and rose petals. Our findings revealed inhibition of protein synthesis as a likely target of MtDef4 and the potential of its cation-tolerant variant as a peptide-based fungicide.

Asymmetries among soil fungicide residues, nitrous oxide emissions and microbiomes regulated by nitrification inhibitor at different moistures.

Carbendazim residue has been widely concerned, and nitrous oxide (N2O) is one of the dominant greenhouse gases. Microbial metabolisms are fundamental processes of removing organic pollutant and producing N2O. Nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) can change soil abiotic properties and microbial communities and simultaneously affect carbendazim degradation and N2O emission. In this study, the comprehensive linkages among carbendazim residue, N2O emission and microbial community after the DMPP application were quantified under different soil moistures. Under 90% WHC, the DMPP application significantly reduced carbendazim residue by 54.82% and reduced soil N2O emission by 98.68%. The carbendazim residue was negatively related to soil ammonium nitrogen (NH4+-N), urease activity, and ratios of Bacteroidetes, Thaumarchaeota and Nitrospirae under 90% WHC, and the N2O emission was negatively related to NH4+-N content and relative abundance of Acidobacteria under the 60% WHC condition. In the whole (60% and 90% WHC together), the carbendazim residue was negatively related to the abundances of nrfA (correlation coefficient = -0.623) and nrfH (correlation coefficient = -0.468) genes. The hao gene was negatively related to the carbendazim residue but was positively related to the N2O emission rate. The DMPP application had the promising potential to simultaneously reduce ecological risks of fungicide residue and N2O emission via altering soil abiotic properties, microbial activities and communities and functional genes. ENVIRONMENTAL IMPLICATION: Carbendazim was a high-efficiency fungicide that was widely used in agricultural production. Nitrous oxide (N2O) is the third most important greenhouse gas responsible for global warming. The 3, 4-dimethylpyrazole phosphate (DMPP) is an effective nitrification inhibitor widely used in agricultural production. This study indicated that the DMPP application reduced soil carbendazim residues and N2O emission. The asymmetric linkages among the carbendazim residue, N2O emission, microbial community and functional gene abundance were regulated by the DMPP application and soil moisture. The results could broaden our horizons on the utilizations DMPP in decreasing fungicide risks and N2O emission.

Modification of the existing maximum residue levels for fluxapyroxad in kaki/Japanese persimmons and cultivated mushrooms.

In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant BASF SE submitted two requests to the competent national authority in Spain and Ireland to modify the existing maximum residue levels (MRLs) for the active substance fluxapyroxad in kaki/Japanese persimmons and in cultivated fungi, respectively. The data submitted in support of the requests were found to be sufficient to derive MRL proposals for kaki/Japanese persimmons and cultivated fungi. Adequate analytical methods for enforcement are available to control the residues of fluxapyroxad on the commodities under consideration at the validated LOQ of 0.01 mg/kg. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the use of fluxapyroxad, according to the reported agricultural practices, is unlikely to present a risk to consumer health. The long-term consumer risk assessment is indicative, pending the submission of the confirmatory data requested under the MRL review.

Host range characterization of Phytophthora sansomeana across corn, soybean, wheat, winter cereal rye, dry bean and oats, and an in vitro assessment of seed treatment sensitivity.

Formally described in 2009, Phytophthora sansomeana is a pathogen of increasing interest in native, agricultural, and horticulturally important plant species. The objective of this study was to elucidate the symptomatic and asymptomatic host range of P. sansomeana on six agricultural crop species commonly used in field crop rotations in Michigan. In addition, sensitivity to oomicides commonly used in seed treatments including, oxathiapiprolin, mefenoxam, ethaboxam, and pyraclostrobin was performed to aid in disease management recommendations. Plant biomass, quantity of P. sansomeana DNA in roots, and reisolations were used to assess pathogenicity and virulence of eighteen isolates of P. sansomeana on each plant species using an inoculated seedling growth chamber assay. Isolates displayed varying levels of virulence to the hosts tested. Reisolations were completed for each plant species tested, and varying quantities of P. sansomeana DNA were found within all plant species root samples. Corn, wheat, soybean, dry bean, and winter cereal rye plants were symptomatic hosts with significant reduction observed in total plant biomass. No significant reduction in total plant biomass was observed in oats, and oat roots harbored the least amount of P. sansomeana DNA. No P. sansomeana isolates were insensitive to the oomicide compounds tested with mean absolute EC50 values of 7.8 x 10-2 µg/ml for mefenoxam, 1.13 x 10-1 µg/ml for ethaboxam, 2.6 x 10-2 µg/ml for oxathiapiprolin, and 3.04 x 10-1 µg/ml for pyraclostrobin. These results suggest that common crop rotations in Michigan may not be a viable option to reduce soilborne inoculum accumulation and oomicide seed treatments should be considered for early season management of P. sansomeana.

Chitosan nanoparticle and its effect on Neoscytalidium novaehollandiae, the causal agent of mulberry canker in Tehran.

Fungal pathogen "Neoscytalidium novaehollandiae" is the causal agent of trunk canker in mulberry trees. Mulberry is considered as most valuable tree for landscaping in Tehran. Here in, for the first time, chitosan nanoparticles (CSNPs) were used to inhibit canker disease causal agent of mulberry. For this purpose, CSNPs were synthesized with a yield of 86%, and after characterization of the synthesized nanoparticles, the growth inhibition rate of fungus (GI%) was evaluated. The results of in vitro assays showed that the concentration of 1500 ppm significantly (P ≤ 0.05) decreased the radial growth of the fungus in comparison with control. For in vivo experiments, 2-year-old branches from healthy randomly selected mulberry trees in the landscape, were inoculated artificially in the laboratory with mycelial plugs from a 7-day-old culture of fungus. The infected branches were then treated with 500, 1000, and 1500 ppm of CSNPs. The results indicated that the disease severity (DS%) in all the treatments and the control plants increased over time. However, the slope of the changes in DS was less in CSNPs treated compared to control. This effect was concentration dependent so that no disease progress was observed at 1500 ppm of CSNPs. The findings indicate the effectiveness of CSNPs in control of canker disease of mulberry caused by N. novaehollandiae.

Knowledge and perception of cereal farmers and extension agents on fungicide use in Northern Ghana.

BACKGROUND: Agricultural pesticide use in sub-Saharan Africa has doubled over the past three decades; with a greater relative increase for fungicides. As pesticide inputs continues to rise, so does the potential for the development of resistance. Here, we report on a survey conducted to understand pesticide resistance awareness, pesticide use knowledge and practices of growers and agricultural extension officers (AEOs) in the cereals growing-belt of Northern Ghana, with emphasis on fungicides. The results may inform development of strategies for improving pesticide literacy including resistance awareness, extension services, and crop protection outcomes. RESULTS: The survey revealed a low level of pesticide use knowledge for AEOs and growers. This was more so for growers with low education, predominantly women. Education level (and indirectly gender) influenced perceived effectiveness of fungicides and levels of adoption of cultural and agrochemical best practices. Only 28% of growers and 11% of AEOs practice crop and fungicide rotations, respectively. More than half (53%) of the respondents indicated that fungicides used in Northern Ghana are not effective. CONCLUSION: Given the low level of pesticide literacy of AEOs and growers, training programs on best practice on the use of pesticides, with targeted initiatives for female growers would improve crop protection outcomes, and safety. The limited adoptions of crop rotation and repeated use of fungicides with the same active ingredients, along with >50% of respondents reporting 'fungicides not working' suggest the potential presence of fungicide resistance cases in growers' fields in the Northern region of Ghana. Further work is needed to determine the incidence of resistance in the region. It is recommended that a key policy priority should focus on understanding broader agrochemical use practices, crop losses and household-level food security in the presence of resistance risks. This article is protected by copyright. All rights reserved.

Long-term, landscape-level assessment of aquatic pesticide exposure to identify amphibian ontological traits affecting vulnerability.

Amphibians worldwide are threatened by habitat loss, some of which is driven by a changing climate, as well as exposure to pesticides, among other causes. The timing and duration of the larval development phase vary between species, thereby influencing the relative impacts of stochastic hydroregime conditions as well as potential aquatic pesticide exposure. We describe the stages of breeding through metamorphosis for eight amphibian species, based on optimal hydroregime conditions, and use a model of pesticide fate and exposure representative of central Florida citrus groves to simulate hydrodynamics based on observed weather data over a 54-year period. Using the Pesticide in Water Calculator and Plant Assessment Tool, we estimated daily wetland depth and pyraclostrobin exposure, with label-recommended application quantities. Species' timing and duration of larval development determined the number of years of suitable hydroregime for breeding and the likelihood of exposure to peak aquatic concentrations of pyraclostrobin. Although the timing of pesticide application determined the number of surviving larvae, density-dependent constraints of wetland hydroregime also affected larval survival across species and seasons. Further defining categorical amphibian life history types and habitat requirements supports the development of screening-level assessments by incorporating environmental stochasticity at the appropriate temporal resolution. Subsequent refinement of these screening-level risk assessment strategies to include spatially explicit landscape data along with terrestrial exposure estimates would offer additional insights into species vulnerability to pesticide exposure throughout the life cycle. Computational simulation of ecologically relevant exposure scenarios, such as these, offers a more realistic interpretation of differential agrichemical risk among species based on their phenology and habits and provides a more situation-specific risk assessment perspective for threatened species. Integr Environ Assess Manag 2024;00:1-10. Published 2024. This article is a U.S. Government work and is in the public domain in the USA.

Characterization of the fludioxonil and phenamacril dual resistant mutants of Fusarium graminearum.

Fusarium graminearum is an important fungal pathogen causing Fusarium head blight (FHB) in wheat and other cereal crops worldwide. Due to lack of resistant wheat cultivars, FHB control mainly relies on application of chemical fungicides. Both fludioxonil (a phenylpyrrole compound) and phenamacril (a cyanoacrylate fungicide) have been registered for controlling FHB in China, however, fludioxonil-resistant isolates of F. graminearum have been detected in field. To evaluate the potential risk of dual resistance of F. graminearum to both compounds, fludioxonil and phenamacril dual resistant (DR) mutants of F. graminearum were obtained via fungicide domestication in laboratory. Result showed that resistance of the DR mutants to both fludioxonil and phenamacril were genetically stable after sub-cultured for ten generations or stored at 4 °C for 30 days on fungicide-free PDA. Cross-resistance assay showed that the DR mutants remain sensitive to other groups of fungicides, including carbendazim, tebuconazole, pydiflumetofen, and fluazinam. In addition, the DR mutants exhibited defects in mycelia growth, conidiation, mycotoxin deoxynivalenol (DON) production, and virulence Moreover, the DR mutants displayed increased sensitivity to osmotic stress. Sequencing results showed that amino acid point mutations S217L/T in the myosin I protein is responsible for phenamacril resistance in the DR mutants. Our results indicate that mutations leading to fludioxonil and phenamacril dual resistance could result in fitness cost for F. graminearum. Our results also suggest that the potential risk of F. graminearum developing resistance to both fludioxonil and phenamacril in field could be rather low, which provides scientific guidance in controlling FHB with fludioxonil and phenamacril.

Characterization of Fusarium species causing soybean root rot in Heilongjiang, China, and mechanism underlying the differences in sensitivity to DMI fungicides.

Soybean root rot is a worldwide soil-borne disease threatening soybean production, causing large losses in soybean yield and quality. Fusarium species are the most detrimental pathogens of soybean root rot worldwide, causing large production losses. Fusarium root rot has been frequently reported in Heilongjiang Province of China, but the predominant Fusarium species and the sensitivity of these pathogens to different fungicides remain unclear. In this study, diseased soybean roots were collected from 14 regions of Heilongjiang province in 2021 and 2022. A total of 144 isolates of Fusarium spp. were isolated and identified as seven distinct species: F. scirpi, F. oxysporum, F. graminearum, F. clavum, F. acuminatum, F. avenaceum, and F. sporotrichioide. F. scirpi and F. oxysporum had high separation frequency and strong pathogenicity. The sensitivity of Fusarium spp. to five different fungicides was determined. Mefentrifluconazole and fludioxonil showed good inhibitory effects, and the sensitivity to pydiflumetofen and phenamacril varied between Fusarium species. In particular, the activity of DMI fungicide prothioconazole was lower than that of mefentrifluconazole. Molecular docking showed that mefentrifluconazole mainly bound to CYP51C, but prothioconazole mainly bound to CYP51B. Furthermore, the sensitivity to prothioconazole only significantly decreased in ΔFgCYP51B mutant, and the sensitivity to mefentrifluconazole changed in ΔFgCYP51C and ΔFgCYP51A mutants. The results demonstrated that the predominant Fusarium species causing soybean root rot in Heilongjiang province were F. scirpi and F. oxysporum and DMI fungicides had differences in binding cavity due to the diversity of CYP51 proteins in Fusarium.

Development and implementation of a novel CAPS assay reveals high prevalence of a boscalid resistance marker and its co-occurrence with an azole resistance marker in Erysiphe necator.

Succinate dehydrogenase inhibitors (SDHIs), are frequently used against powdery mildew (PM) fungi, such as Erysiphe necator, the causal agent of grapevine PM. Fungicide resistance, however, hinders effective control. DNA-based monitoring facilitates the recognition of resistance. We aimed (i) to adapt an effective method to detect a widespread genetic marker of resistance to boscalid, a commonly used SDHI, and (ii) to study the co-occurrence of the marker with a marker of resistance to demethylase inhibitor (DMI) fungicides. Sequencing of the sdhB gene identified a non-synonymous substitution, denoted as sdhB-A794G, leading to an amino acid change (H242R) in the sdhB protein. In vitro fungicide resistance tests showed that E. necator isolates carrying sdhB-A794G were resistant to boscalid. We adopted a cleaved amplified polymorphic sequence-based method and screened more than 500 field samples collected from five Hungarian wine regions in two consecutive years. The sdhB-A794G marker was detected in all wine regions and in both years, altogether in 61.7% of samples, including 20.5% in which both sdhB-A794G and the wild-type were present. The frequency of sdhB-A794G was higher in SDHI-treated vineyards than in vineyards without any SDHI application. A significant difference in the presence of the marker was detected among wine regions; its prevalence ranged from none to 100%. We identified significant co-occurrence of sdhB-A794G with the CYP51-A495T (Y136F) mutation of the CYP51 gene, a known marker of resistance to DMIs. The monitoring of fungicide resistance is fundamental for the successful control of E. necator. Our rapid, cost-effective diagnostic method will support decision-making and fungicide resistance monitoring and management.

Global spread, genetic differentiation and selection of barley spot form of net blotch isolates.

Spot form of net blotch, caused by Pyrenophora teres f. maculata, is a significant necrotrophic disease of barley that spread world-wide in the 20th century. Genetic relationships were analysed to determine the diversity, survival and dispersal of a diverse collection of 346 isolates from Australia, Southern Africa, North America, Asia Minor and Europe. The results, based on genome-wide DArTseq data, indicated isolates from Turkey were the most differentiated with regional sub-structuring, together with individuals closely related to geographically distant genotypes. Elsewhere, population subdivision related to country of origin was evident, although low levels of admixturing was found that may represent rare genotypes or migration from unsampled populations. Canadian isolates were the next most diverged and Australian and South African the most closely related. With the exception of Turkish isolates, multiple independent Cyp51A mutation events (which confer insensitivity to demethylation inhibitor fungicides) between countries and within regions was evident, with strong selection for a transposable element insertion at the 3' end of the promoter and counter-selection elsewhere. Individuals from Western Australia shared genomic regions and Cyp51A haplotypes with South African isolates, suggesting a recent common origin.

The Use and Impact of Antibiotics in Plant Agriculture: A Review.

Growers have depended on the specificity and efficacy of streptomycin and oxytetracycline as a part of their plant disease arsenal since the middle of the twentieth century. With climate change intensifying plant bacterial epidemics, the established success of these antibiotics remains threatened. Our strong reliance on certain antibiotics for devastating diseases eventually gave way to resistance development. Though antibiotics in plant agriculture equal to less than 0.5% of overall antibiotic use in the US, it is still imperative for humans to continue to monitor usage, environmental residues, and resistance in bacterial populations. This review provides an overview of the history and use, resistance and mitigation, regulation, environmental impact, and economics of antibiotics in plant agriculture. Bacterial issues, such as the ongoing Huanglongbing (citrus greening) epidemic in Florida citrus production, may need antibiotics for adequate control. Therefore, preserving the efficacy of our current antibiotics by utilizing more targeted application methods, such as trunk injection, should be a major focus.