Bacillus velezensis BE2 controls wheat and barley diseases by direct antagonism and induced systemic resistance

Wheat and barley rank among the main crops cultivated on a global scale, providing the essential nutritional foundation for both humans and animals. Nevertheless, these crops are vulnerable to several fungal diseases, such as Septoria tritici blotch and net blotch, which significantly reduce yields by adversely affecting leaves and grain quality. To mitigate the effect of these diseases, chemical fungicides have proven to be genuinely effective; however, they impose a serious environmental burden. Currently, biocontrol agents have attracted attention as a sustainable alternative to fungicides, offering an eco-friendly option. The study aimed to assess the efficacy of Bacillus velezensis BE2 in reducing disease symptoms caused by Zymoseptoria tritici and Pyrenophora teres. This bacterium exhibited significant antagonistic effects in vitro by suppressing fungal development when pathogens and the beneficial strain were in direct confrontation. These findings were subsequently confirmed through microscopic analysis, which illustrated the strain's capacity to inhibit spore germination and mycelial growth in both pathogens. Additionally, the study analysed the cell-free supernatant of the bacterium using UPLC-MS (ultra-performance liquid chromatography-mass spectrometry). The results revealed that strain BE2 produces, among other metabolites, different families of cyclic lipopeptides that may be involved in biocontrol. Furthermore, the beneficial effects of strain BE2 in planta were assessed by quantifying the fungal DNA content directly at the leaf level after bacterization, using two different application methods (foliar and drenching). The results indicated that applying the beneficial bacterium at the root level significantly reduced pathogens pressure. Finally, gene expression analysis of different markers showed that BE2 application induced a priming effect within the first hours after infection. KEY POINTS: • BE2 managed Z. tritici and P. teres by direct antagonism and induced systemic resistance. • Strain BE2 produced seven metabolite families, including three cyclic lipopeptides. • Application of strain BE2 at the root level triggered plant defense mechanisms.

Novel yeast-based biosensor for environmental monitoring of tebuconazole

Due to increasing demand for high and stable crop production, human populations are highly dependent on pesticide use for growing and storing food. Environmental monitoring of these agrochemicals is therefore of utmost importance, because of their collateral effects on ecosystem and human health. Even though most current-use analytical methods achieve low detection limits, they require procedures that are too complex and costly for routine monitoring. As such, there has been an increased interest in biosensors as alternative or complementary tools to streamline detection and quantification of environmental contaminants. In this work, we developed a biosensor for environmental monitoring of tebuconazole (TEB), a common agrochemical fungicide. For that purpose, we engineered S. cerevisiae cells with a reporter gene downstream of specific promoters that are expressed after exposure to TEB and characterized the sensitivity and specificity of this model system. After optimization, we found that this easy-to-use biosensor consistently detects TEB at concentrations above 5 μg L-1 and does not respond to realistic environmental concentrations of other tested azoles, suggesting it is specific. We propose the use of this system as a complementary tool in environmental monitoring programs, namely, in high throughput scenarios requiring screening of numerous samples. KEY POINTS: • A yeast-based biosensor was developed for environmental monitoring of tebuconazole. •The biosensor offers a rapid and easy method for tebuconazole detection ≥ 5 μg L-1. •The biosensor is specific to tebuconazole at environmentally relevant concentrations.

Occurrence and risk assessment of azole fungicides during the urban water cycle: A year-long study along the Yangtze River, China

Azole fungicides (AFs) play an important role in the prevention and treatment of fungal diseases in agricultural crops. However, limited studies are addressing the fate and ecological risk of AFs in the urban water cycle at a large watershed scale. To address this gap, we investigated the spatiotemporal distribution and ecological risk of twenty AFs in the lower reaches of the Yangtze River across four seasons. Carbendazim (CBA), tebuconazole (TBA), tricyclazole (TCA), and propiconazole (PPA) were found to be the dominant compounds. Their highest concentrations were measured in January (188.3 ng/L), and November (2197.1 ng/L), July (162.0 ng/L), and November (1801.9 ng/L), respectively. The comparison between wastewater treatment plants (WWTPs) effluents and surface water suggested that industrial WWTPs are major sources of AFs in the Yangtze River. In particular, TBA and PPA were found to be the most recalcitrant AFs in industrial WWTPs, while difenoconazole (DFA) was found to be the most potent pollutant in municipal WWTPs, with an average removal rate of less than 60%. The average risk quotient (RQ) for the entire AFs was 6.45 in the fall, which was higher than in January (0.98), April (0.61), and July (0.40). This indicates that AFs in surface water posed higher environmental risks during the dry season. Additionally, the exposure risk of AFs via drinking water for sensitive populations deserves more attention. This study provides benchmark data on the occurrence of AFs in the lower reaches of the Yangtze River, and offers suggestions for better reduction of AFs.

Leaching of unexpected cyazofamid degradation products into groundwater demonstrates gaps in current pesticide risk assessment

To investigate the formation and leaching potential of degradation products N,N-dimethylsulfamide (DMS) and dimethylsulfamic acid (DMSA) from cyazofamid under real-world agricultural conditions, the fungicide cyazofamid was applied in a potato crop as part of the Danish Pesticide Leaching Assessment Programme (PLAP). Leaching of DMS, DMSA, 4-chloro-5-(4-methylphenyl)-1H-imidazole-2-carbonitrile (CCIM), and 4-chloro-5-(4-methylphenyl)-1H-imidazole-2-carboxylicacid (CTCA) was monitored in water from the variably saturated zone (suction cups) and groundwater for more than two years following the applications. In total, 424 samples were analyzed for the content of the four degradation products. An additional laboratory study was executed in parallel with the field monitoring study. Here, cyazofamid was applied to soil columns and leaching of the four degradation products was studied under controlled conditions. In the EFSA conclusion on cyazofamid, CCIM and CTCA are mentioned as major relevant metabolites; DMS is not mentioned in the risk assessment and DMSA is only included in acute oral toxicity studies and an in vitro bacterial mutation assay. In contrast to the EFSA conclusion on cyazofamid, our studies showed no leaching of the two major metabolites, CTCA and CCIM, but instead, major leaching of DMS and DMSA in both the field and laboratory studies was observed. That is, both DMS and DMSA leached to the groundwater in concentrations >0.1 μg/L for more than half a year. Based on this, we suggest improvements to the current pesticide risk assessment.

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.

Biocontrol of Alternaria alternata in cold-stored table grapes using psychrotrophic yeasts and bioactive compounds of natural sources

Alternaria alternata is a common fungal pathogen causing postharvest decay in table grapes. This study addressed the potential of autochthonous yeasts and bioactive compounds of natural sources to act as biocontrol agents (BCAs) against A. alternata in cold-stored table grapes. With this purpose, 19 yeast capable of growing at 0-1 °C were isolated from the surface of Red Globe table grapes. These isolates, along with the pre-isolated strain Metschnikowia pulcherrima RCM2, were evaluated as BCAs in wounded berries. From these results, six yeast isolates were pre-selected to be combined with bioactive compounds of natural sources, like phenolic compounds (PCs) of side streams of wine industry, including bunch stem extract (BSE) (5-25 %), and cane extract (CE) (5-25 %), and functional polysaccharides from shrimp waste such as chitosan (CH) (0.5 %). Then, the biocontrol efficacy of combined treatments beyond individual ones was compared. The results revealed that 4 yeast isolates, namely M. pulcherrima RCM2 and ULA146, and Aureobasidium pullulans FUL14 and FUL18, were the most effective. However, when combined with the natural bioactive compounds, their efficacy against A. alternata did not increase significantly. Notably, ULA146 and FUL18 demonstrated a biocontrol efficacy of 36-37 %, comparable to that of the treatment with commercial doses of SO2, which only showed a 27 % reduction in the lesion diameter. These findings highlight the potential of using psychrotrophic yeasts as BCAs against A. alternata in cold-stored table grapes. Combining these yeast strains with BSE, CE and CH did not increase BCAs efficacy against this pathogen at the concentrations tested. The development of effective biocontrol strategies for A. alternata could contribute to reducing reliance on chemically synthesized fungicides, promoting sustainable practices, aiming to improve the quality and safety of cold-stored table grapes.

Antimicrobial and anti-diabetic efficiency of Polyalthia longifolia leaf extracts and major compounds characterization

This research was performed to investigate the bactericidal and fungicidal competence of extracts (methanol and petroleum ether extract) of Polyalthia longifolia leaf. Moreover, the major active compounds present in the effective crude extract (either methanol or petroleum ether extract) was determined through initially with UV-Vis spectra, FTIR, and GC-MS analyses. The methanol extract alone showed remarkable bactericidal and fungicidal activity against the bacterial (S. pyogenes > E. coli > S. aureus > S. pneumoniae > C. difficile > P. aeruginosa) and fungal (A. clavatus > C. albicans > A. niger > A. fumigatus > C. tropicalis > C. auris) pathogens at increased concentration (12.5 mg mL-1) than petroleum ether extract. The MIC and MBC values of methanol extract were found as 10-20 mg mL-1 and 30-40 mg mL-1 respectively. The MFC value of methanol extract was found as 10-20 mg mL-1. These MIC, MBC, and MFC values of methanol extract were considerably greater than petroleum ether extract. The FTIR and GC-MS characterization studies revealed that the presence of more acre functional groups belonging to bioactive compounds such as Z)-7-Hexadecenal, Aromandendrene, α-Curcumene, Caryophyllene, Methyl 14-methyl Pentadecanoat, Methyl trans-13-Octadecenoate, 9-Octadecenoic acid (Z)-, and 2-hydroxy-1- (hydroxymethyl)ethyl. As a result of these findings, it is possible that P. longifolia leaf methanol extract contains medicinally important bioactive substances with bactericidal and fungicidal properties.

Investigating the applicability domain of the hiPSC-based PluriLum assay: an embryotoxicity assessment of chemicals and drugs

To meet the growing demand for developmental toxicity assessment of chemicals, New Approach Methodologies (NAMs) are needed. Previously, we developed two 3D in vitro assays based on human-induced pluripotent stem cells (hiPSC) and cardiomyocyte differentiation: the PluriBeat assay, based on assessment of beating differentiated embryoid bodies, and the PluriLum assay, a reporter gene assay based on the expression of the early cardiac marker NKX2.5; both promising assays for predicting embryotoxic effects of chemicals and drugs. In this work, we aimed to further describe the predictive power of the PluriLum assay and compare its sensitivity with PluriBeat and similar human stem cell-based assays developed by others. For this purpose, we assessed the toxicity of a panel of ten chemicals from different chemical classes, consisting of the known developmental toxicants 5-fluorouracil, all-trans retinoic acid and valproic acid, as well as the negative control compounds ascorbic acid and folic acid. In addition, the fungicides epoxiconazole and prochloraz, and three perfluoroalkyl substances (PFAS), PFOS, PFOA and GenX were tested. Generally, the PluriLum assay displayed higher sensitivity when compared to the PluriBeat assay. For several compounds the luminescence readout of the PluriLum assay showed effects not detected by the PluriBeat assay, including two PFAS compounds and the two fungicides. Overall, we find that the PluriLum assay has the potential to provide a fast and objective detection of developmental toxicants and has a level of sensitivity that is comparable to or higher than other in vitro assays also based on human stem cells and cardiomyocyte differentiation for assessment of developmental toxicity.

Manipulation of soil mycorrhizal fungi influences floral traits

Most plants form root hyphal relationships with mycorrhizal fungi, especially arbuscular mycorrhizal fungi (AMF). These associations are known to positively impact plant biomass and competitive ability. However, less is known about how mycorrhizas impact other ecological interactions, such as those mediated by pollinators. We performed a meta-regression of studies that manipulated AMF and measured traits related to pollination, including floral display size, rewards, visitation, and reproduction, extracting 63 studies with 423 effects. On average, the presence of mycorrhizas was associated with positive effects on floral traits. Specifically, we found impacts of AMF on floral display size, pollinator visitation and reproduction, and a positive but nonsignificant impact on rewards. Studies manipulating mycorrhizas with fungicide tended to report contrasting results, possibly because fungicide destroys both beneficial and pathogenic microbes. Our study highlights the potential for relationships with mycorrhizal fungi to play an important, yet underrecognized role in plant-pollinator interactions. With heightened awareness of the need for a more sustainable agricultural industry, mycorrhizal fungi may offer the opportunity to reduce reliance on inorganic fertilizers. At the same time, fungicides are now ubiquitous in agricultural systems. Our study demonstrates indirect ways in which plant-belowground fungal partnerships could manifest in plant-pollinator interactions.

Metabolomics approach to understand molecular mechanisms involved in fungal pathogen-citrus pathosystems

Citrus is a crucial crop with a significant economic impact globally. However, postharvest decay caused by fungal pathogens poses a considerable threat, leading to substantial financial losses. Penicillium digitatum, Penicillium italicum, Geotrichum citri-aurantii and Phyllosticta citricarpa are the main fungal pathogens, causing green mold, blue mold, sour rot and citrus black spot diseases, respectively. The use of chemical fungicides as a control strategy in citrus raises concerns about food and environmental safety. Therefore, understanding the molecular basis of host-pathogen interactions is essential to find safer alternatives. This review highlights the potential of the metabolomics approach in the search for bioactive compounds involved in the pathogen-citrus interaction, and how the integration of metabolomics and genomics contributes to the understanding of secondary metabolites associated with fungal virulence and the fungal infection mechanisms. Our goal is to provide a pipeline combining metabolomics and genomics that can effectively guide researchers to perform studies aiming to contribute to the understanding of the fundamental chemical and biochemical aspects of pathogen-host interactions, in order to effectively develop new alternatives for fungal diseases in citrus cultivation. We intend to inspire the scientific community to question unexplored biological systems, and to employ diverse analytical approaches and metabolomics techniques to address outstanding questions about the non-studied pathosystems from a chemical biology perspective.

Bacteria-mediated green synthesis of silver nanoparticles and their antifungal potentials against Aspergillus flavus

The best biocontroller Bacillus subtilis produced silver nanoparticles (AgNPs) with a spherical form and a 62 nm size through green synthesis. Using UV-vis spectroscopy, PSA, and zeta potential analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy, the properties of synthesized silver nanoparticles were determined. Silver nanoparticles were tested for their antifungicidal efficacy against the most virulent isolate of the Aspergillus flavus fungus, JAM-JKB-BHA-GG20, and among the 10 different treatments, the treatment T6 [PDA + 1 ml of NP (19: 1)] + Pathogen was shown to be extremely significant (82.53%). TG-51 and GG-22 were found to be the most sensitive groundnut varieties after 5 and 10 days of LC-MS QTOF infection when 25 different groundnut varieties were screened using the most toxic Aspergillus flavus isolate JAM- JKB-BHA-GG20, respectively. In this research, the most susceptible groundnut cultivar, designated GG-22, was tested. Because less aflatoxin (1651.15 g.kg-1) was observed, treatment T8 (Seed + Pathogen + 2 ml silver nanoparticles) was determined to be much more effective. The treated samples were examined by Inductively Coupled Plasma Mass Spectrometry for the detection of metal ions and the fungicide carbendazim. Ag particles (0.8 g/g-1) and the fungicide carbendazim (0.025 g/g-1) were found during Inductively Coupled Plasma Mass Spectrometry analysis below detectable levels. To protect plants against the invasion of fungal pathogens, environmentally friendly green silver nanoparticle antagonists with antifungal properties were able to prevent the synthesis of mycotoxin by up to 82.53%.

An electrochemical sensor for the determination of environmentally hazardous fungicide pyrimethanil in water and fruit samples

We developed a facile electroanalytical system for the rapid and sensitive detection of pyrimethanil through the modification of carbon paste electrode surface using the as-fabricated europium doped feather-type CuO nanoflowers (FT-Eu3+-CuO NF sensor). The peak current of pyrimethanil oxidation was elevated by the sensor due to the integration of appreciable electrochemical features of the modifier, which indicates the high ability of the modified electrode to enhance the sensitivity of pyrimethanil detection. The pyrimethanil sensor under the optimized setting had a broad linear dynamic range (0.001-800.0 μM) and a narrow limit of detection (0.18 nM). The practical applicability of the as-fabricated electrode was verified by sensing pyrimethanil in real samples; it also exhibited commendable specificity, stability and reproducibility.

Fitness difference between two synonymous mutations of Phytophthora infestans ATP6 gene

BACKGROUND

Sequence variation produced by mutation provides the ultimate source of natural selection for species adaptation. Unlike nonsynonymous mutation, synonymous mutations are generally considered to be selectively neutral but accumulating evidence suggests they also contribute to species adaptation by regulating the flow of genetic information and the development of functional traits. In this study, we analysed sequence characteristics of ATP6, a housekeeping gene from 139 Phytophthora infestans isolates, and compared the fitness components including metabolic rate, temperature sensitivity, aggressiveness, and fungicide tolerance among synonymous mutations.

RESULTS

We found that the housekeeping gene exhibited low genetic variation and was represented by two major synonymous mutants at similar frequency (0.496 and 0.468, respectively). The two synonymous mutants were generated by a single nucleotide substitution but differed significantly in fitness as well as temperature-mediated spatial distribution and expression. The synonymous mutant ending in AT was more common in cold regions and was more expressed at lower experimental temperature than the synonymous mutant ending in GC and vice versa.

CONCLUSION

Our results are consistent with the argument that synonymous mutations can modulate the adaptive evolution of species including pathogens and have important implications for sustainable disease management, especially under climate change.

Determinants of pesticides use among tomato farmers in the Bono and Ahafo regions of Ghana

Tomato production plays a crucial role in the livelihoods of farmers and agricultural households in the forest savanna transitional belt of Ghana. However, the success of tomato cultivation is hindered by the presence of insect pests and diseases, necessitating the use of agricultural inputs. This study aimed to identify the pesticides used in tomato farming, assess their World Health Organization (WHO) active ingredient hazard class, determine the precautionary behaviour associated with pesticide use by tomato farmers, and elucidate the socio-economic factors influencing pesticide usage in the Bono and Ahafo regions of Ghana. A multistage sampling procedure was employed to select 1009 respondents, who were administered a structured questionnaire. Descriptive statistics and logistic regression models were used to analyse the collected data. The results revealed that tomato farmers utilized 15 types of insecticides (e.g., lambda and chlorpyrifos ethyl based), 8 types of fungicides (e.g., mancozeb and sulphur + copper based), and 6 types of weedicides (mostly glyphosate based) on their crops. Notably, four insecticides and two fungicides types were found to be unregistered products. Lambda-cyhalothrin-based insecticides and mancozeb-based fungicides were predominantly used by the farmers. The assessed pesticides exhibited varying levels of hazard, ranging from slight to moderate. The study found that farmer training was a significant driver influencing insecticide use, while the educational level of farmers and average yield played important roles in determining fungicide use. Socio-economic factors such as being the head of the household, employing farm workers, the cultivated tomato variety, and farmer training influenced weedicide use. The type of tomato variety cultivated emerged as the primary socio-economic driver of pesticide use. The study recommended the establishment and implementation of a systematic monitoring regime for pesticide product marketing and use, with the aim of reducing the utilization of unregistered products by farmers. Implementing these measures supports sustainable tomato farming in the Bono and Ahafo regions of Ghana.

An azole fungicide climbazole damages the gut-brain axis in the grass carp

Azole antifungal climbazole has frequently been detected in aquatic environments and shows various effects in fish. However, the underlying mechanism of toxicity through the gut-brain axis of climbazole is unclear. Here, we investigated the effects of climbazole at environmental concentrations on the microbiota-intestine-brain axis in grass carp via histopathological observation, gene expression and biochemical analyses, and high-throughput sequencing of the 16 S rRNA. Results showed that exposure to 0.2 to 20 μg/L climbazole for 42 days significantly disrupted gut microbiota and caused brain neurotoxicity in grass carp. In this study, there was an alteration in the phylum and genus compositions in the gut microbiota following climbazole treatment, including reducing Fusobacteria (e.g., Cetobacterium) and increasing Actinobacteria (e.g., Nocardia). Climbazole disrupted intestinal microbial abundance, leading to increased levels of lipopolysaccharide and tumor necrosis factor-alpha in the gut, serum, and brain. They passed through the impaired intestinal barrier into the circulation and caused the destruction of the blood-brain barrier through the gut-brain axis, allowing them into the brain. In the brain, climbazole activated the nuclear factor kappaB pathway to increase inflammation, and suppressed the E2-related factor 2 pathway to produce oxidative damage, resulting in apoptosis, which promoted neuroinflammation and neuronal death. Besides, our results suggested that this neurotoxicity was caused by the breakdown of the microbiota-gut-brain axis, mediated by reduced concentrations of dopamine, short chain fatty acids, and intestinal microbial activity induced by climbazole.

Association of pesticide exposure with neurobehavioral outcomes among avocado farmworkers in Mexico

BACKGROUND AND AIM

To date, few studies have focused on the health effects of pesticide exposure among avocado farmworkers. We examined the association of exposure to insecticides, fungicides, and herbicides with cognitive and mental health outcomes among these avocado workers from Michoacan, Mexico.

MATERIALS AND METHODS

We conducted a cross-sectional study of 105 avocado farmworkers between May and August 2021. We collected data on self-reported pesticide use during the 12 months prior to the baseline survey and estimated annual exposure-intensity scores (EIS) using a semi-quantitative exposure algorithm. We calculated specific gravity adjusted average concentrations of 12 insecticide, fungicide, or herbicide metabolites measured in urine samples collected during two study visits (8-10 weeks apart). We assessed participants' cognitive function and psychological distress using the NIH Toolbox Cognition Battery and the Brief Symptom Inventory 18 (BSI-18), respectively. We examined individual associations of EIS and urinary pesticide metabolites with neurobehavioral outcomes using generalized linear regression models. We also implemented Bayesian Weighted Quantile Sum (BWQS) regression to evaluate the association between a pesticide metabolite mixture and neurobehavioral outcomes.

RESULTS

In individual models, after adjusting for multiple comparisons, higher concentrations of hydroxy-tebuconazole (OH-TEB, metabolite of fungicide tebuconazole) were associated with higher anxiety (IRR per two-fold increase in concentrations = 1.26, 95% CI:1.08, 1.48) and Global Severity Index (GSI) (IRR = 1.89, 95% CI:1.36, 2.75) scores, whereas higher concentrations of 3,5,6-trichloro-2-pyridinol (TCPy, metabolite of chlorpyrifos) were associated with lower GSI scores (IRR = 0.69, 95% CI: 0.56, 0.85). In BWQS analyses, we found evidence of a mixture association of urinary pesticide metabolites with higher anxiety (IRR = 1.72, 95% CrI: 1.12, 2.55), depression (IRR = 4.60, 95% CrI: 2.19, 9.43), and GSI (IRR = 1.99, 95% CrI: 1.39, 2.79) scores. OH-TEB and hydroxy-thiabendazole (metabolite of fungicide thiabendazole) combined contributed 54%, 40%, and 54% to the mixture effect in the anxiety symptoms, depression symptoms, and overall psychological distress models, respectively.

CONCLUSIONS

We found that exposure to tebuconazole and thiabendazole, fungicides whose effects have been rarely studied in humans, may be associated with increased psychological distress among avocado farmworkers. We also observed that exposure to chlorpyrifos may be associated with decreased psychological distress.

Oxidant-mediated radical reactions of the azole fungicide TEB in aquatic media: Degradation mechanism and toxicity evolution

The degradation of tebuconazole (TEB) by UV/H2O2, UV/NaClO, and ozonation was investigated in this research. The experimental findings unveiled that under the specified conditions, the degradation percentages of TEB were raised to 99% within 40 s, 5 min, and 3 min for UV/H2O2, UV/NaClO and ozonation, respectively. The mineralization percentages within 1 h were 59%, 31% and 8% for the three AOPs. UV/H2O2 and UV/NaClO technologies mainly acted through OH·, while O3 treatment primarily relied on the free radicals such as 1O2 and O2·-. UV-based AOPs achieved almost complete dechlorination within 1 h, whereas O3 treatment had a less effective dechlorination, reaching only 27.61%. Notably, UV alone achieved a dechlorination percentage of 43.07%. By identifying the TPs, we found that the three AOPs shared three similar degradation pathways. The degradation mechanism of TEB mainly entailed the removal of the benzene ring, tert-butyl group and triazolyl group. Toxicity assessment revealed an initial increase followed by a gradual decrease in toxicity for UV/NaClO and O3 treatments, whereas UV/H2O2 treatment exhibited a sustained decrease. This was due to the presence of TP278 and TP303 by UV/NaClO and TP168 and TP153 by ozonation. After estimating the costs of the three AOPs, UV/H2O2 standed out as the best choice for achieving a 90% degradation percentage and exhibiting lower toxicity performance, while O3 treatment was favored for low TOC demands. These research findings provided valuable reference for understanding the degradation mechanism and developing a new technology of the removal of TEB.

Spatial and temporal variations of currently used pesticides (CUPs) concentrations in ambient air in Wallonia, Belgium

Pesticides are among the most widely used chemicals thus contributing to a global contamination of the environment. Studies in North America and Europe have reported ambient air concentrations of Currently Used Pesticides in rural and urban locations as well as in remote areas. Monitoring pesticides in air is required for a better understanding of human exposure through inhalation and to assess potential health effects related to this exposure pathway. In this study, 46 pesticides were analyzed in ambient air in sampling stations distributed over Wallonia during a year, from May 2015 to May 2016. Different typologies were defined for sampling sites (remote areas, urban sites, agricultural sites, livestock area, and sites with other professional uses). Ambient air was sampled for 14 days with an active air sampler at a flow rate of 4 m³/h. Quartz filters and PUF/XAD-2/PUF cartridges were used to sample both gas and particulate phase pesticides. On the 46 pesticides studied, 6 insecticides, 18 herbicides and 18 fungicides were detected. Herbicides were measured in 68.3% of samples throughout the year, whereas fungicides and insecticides were measured in 62.6% and 13.2% of the samples, respectively. The highest mean concentrations for all pesticides were measured in spring-summer, whereas few pesticides were measured at low concentrations in winter. Six pesticides were measured in the remote sampling station at lower concentrations than in all other sites highlighting volatility of these pesticides. The highest number of different pesticides and the highest concentrations were measured in agricultural stations, where uses of plant protection products are higher. Finally, less volatile pesticides were only detected near application areas and at low concentrations. Together, these results provide better insight on the spatial and temporal variations of pesticides concentrations in ambient air, which were related to pesticides uses as well to atmospheric volatility and persistence.

Bacillus subtilis NBRI-W9 simultaneously activates SAR and ISR against Fusarium chlamydosporum NBRI-FOL7 to increase wilt resistance in tomato

AIMS

The study aimed to determine the pathogenicity of Fusarium species currently prevalent in tomato fields having history of chemical fungicide applications and determine the bio-efficacy of Bacillus subtilis NBRI-W9 as a potent biological control agent.

METHODS AND RESULTS

Fusarium was isolated from surface-sterilized infected tomato plants collected from fields. Pathogenicity of 30 Fusarium isolates was determined by in vitro and in vivo assays. Following Koch's postulates, F. chlamydosporum (FOL7) was identified as a virulent pathogen. The biological control of FOL 7 by B. subtilis NBRI-W9 (W9) and the colonization potential of W9 were established using spontaneous rifampicin-resistant mutants. W9 showed 82% inhibition of FOL7 on a dual-culture plate and colonization levels in tomato plants of ∼5.5, ∼3.3, and ∼2.2 log10 CFU/g in root, stem, and leaf tissue, respectively. Antagonistic activity was shown by scanning electron microscopy (SEM) and cell-wall-degradative enzymes. W9 reduced FOL7 infection in net-house and field experiments by 60% and 41%, respectively. Biochemical investigation, defence enzymes, defence gene expression analysis, SEM, and field studies provide evidence of hyperparasitism and induced resistance as the mode of biological control. The study also demonstrates that the potent biocontrol agent W9, isolated from Piper, can colonize tomato plants, control fungal disease by inducing induced systemic resistance (ISR) and systemic acquired resistance (SAR) simultaneously, and increase crop yield by 21.58% under field conditions.

CONCLUSIONS

This study concludes that F. chlamydosporum (NBRI-FOL7) is a potent, fungicide-resistant pathogen causing wilt in tomatoes. NBRI-W9 controlled FOL7 through mycoparasitism and simultaneously activated ISR and SAR in plants, providing an attractive tool for disease control that acts at multiple levels.

The impact of various forms of silver nanoparticles on the rhizosphere of wheat (Triticum aestivum L.) - Shifts in microbiome structure and predicted microbial metabolic functions

The study investigated the effects of different silver nanoparticles (AgNPs) on the soil microbiome and wheat growth. For comparison purposes, a commercial fungicide and silver nitrate (AgNO3) were used. The results revealed three distinct groups of nanoparticles based on their impacts. Small-size AgNPs (10 nm) with a negative charge, as well as fungicide had limited effects on the microbiome, similar to the no-treatment control. Bigger in size (30-60 nm) and a negative charge AgNPs showed the most beneficial effects on soil microbiota shifts. These AgNPs increased the abundance of bacteria with beneficial traits such as nitrogen-fixing, urease, protease, and lignin degradation bacteria. The third type of AgNPs had a positive charge of nanostructure and influenced specific microbial populations, increasing the abundance of anaerobic and autotrophic groups of microorganisms, which could be assessed as a harmful shift for plants growth promotions and was similar to the AgNO3 treatment. Overall, the study emphasized the potential of AgNPs in agriculture not only as biocidal. The conducted study proved that AgNPs with bigger size/negative charge, used in low concentration can have a surprisingly stimulating effect on the positive characteristics of the rhizosphere microbiome. Moreover, the surface charge of AgNPs is a significant factor affecting microbial activity of wheat rhizosphere soil, which in this treatment is significantly similar to the AgNO3 treatment.

Semisynthesis, anti-oomycete and anti-fungal activities of ursolic acid ester derivatives

Using ursolic acid (UA) as the lead compound, thirteen UA ester derivatives (3 and 7a-l) were synthesized by modifying their C-3 and C-28 positions, respectively, and their structures were well characterized by 1H NMR, 13C NMR, HRMS and melting points. Furthermore, we evaluated the anti-oomycete and anti-fungal activities of these compounds against Phytophthora capsici and Fusarium graminearum in vitro. The results showed that compound 7h exhibited prominent anti-oomycete and anti-fungal activities, and the median effective concentration (EC50) values of 7h against P. capsici and F. graminearum were 70.49 and 113.21 mg/L, respectively. This study suggested that the anti-oomycete and anti-fungal activities of esters synthesized by introducing acyloxy group at C-3 position of UA was more conspicuous than that of esters synthesized by introducing benzyloxy group at C-28 position. This result will pave the way for further modification of UA to develop potential new fungicides.

Exploring the impact of fungicide exposure and nutritional stress on the microbiota and immune response of the Cape honey bee (Apis mellifera capensis)

Honey bees (Apis mellifera) harbour a stable core microbial community within their gut, that is suggested to play a role in metabolic functioning, immune regulation, and host homeostasis. This microbiota presents a unique opportunity to observe the effects of stressors on honey bee health. We examined the effects of two common honey bee stressors: indirect fungicide contamination and nutrient limitation. These effects were observed through changes in their hind- and midgut microbiota using Automated Ribosomal Intergenic Spacer Analysis (ARISA), alongside high-throughput amplicon sequencing. Expression of the honey bees' immune response was examined through the expression of three immune-related genes, namely, immune deficiency (imd), proPhenolOxidase (proPO), and spaetzle (spz). Additionally, longevity of the honey bees was monitored through observation of the expression levels of Vitellogenin (Vg). Both treatment groups were compared to a negative control, and a diseased positive control. There was no effect on the hindgut microbiota due to the stressors, while significant changes in the midgut was observed. This was also observed in the expression of the immune-related genes within the treatment groups. The Imd pathway was substantially downregulated, with upregulation in the prophenoloxidase pathway. However, no significant effect was observed in the expression of spz, and only the pollen treatment group showed reduced longevity through a downregulation of Vg. Overall, the effect of these two common stressors indicate a compromise in honey bee immunity, and potential vulnerabilities within the immune defence mechanisms.

Biocontrol potential of endophytic Pseudomonas strain IALR1619 against two Pythium species in cucumber and hydroponic lettuce

The use of fungicides to manage disease has led to multiple environmental externalities, including resistance development, pollution, and non-target mortality. Growers have limited options as legacy chemistry is withdrawn from the market. Moreover, fungicides are generally labeled for traditional soil-based production, and not for liquid culture systems. Biocontrol agents for disease management are a more sustainable and environmentally friendly alternative to conventional agroprotectants. Pythium ultimum is a soil borne oomycete plant pathogen with a broad taxonomic host range exceeding 300 plants. Cucumber seedlings exposed to P. ultimum 1 day after a protective inoculation with bacterial endophyte accession IALR1619 (Pseudomonas sp.) recorded 59% survival; with the control assessed at 18%. When the pathogen was added 5 days post endophyte inoculation, 74% of the seedlings treated survived, compared to 36% of the control, indicating a longer-term effect of IALR1619. Under hydroponic conditions, IALR1619 treated leaf type lettuce cv. 'Cristabel' and Romaine cv. 'Red Rosie' showed 29% and 42% higher shoot fresh weight compared to their controls, respectively. Similar results with less growth decline were observed for a repeat experiment with IALR1619. Additionally, an experiment on hydroponic lettuce in pots with perlite was carried out with a mixture of P. ultimum and P. dissotocum after IALR1619 inoculation. The endophyte treated 'Cristabel' showed fresh weight gain, but the second cultivar 'Pensacola' yielded no increase. In summary, the endophyte IALR1619 provided short term as well as medium-term protection against Pythium blight in cucumber seedlings and may be used as an alternative to conventional fungicides in a greenhouse setting. This study also demonstrated the potential of ALR1619 as a biocontrol agent against Pythium blight in hydroponic lettuce.

Transcriptome profile of pecan scab resistant and susceptible trees from a pecan provenance collection

Pecan scab is a devastating disease that causes damage to pecan (Carya illinoinensis (Wangenh.) K. Koch) fruit and leaves. The disease is caused by the fungus Venturia effusa (G. Winter) and the main management practice for controlling the disease is by application of fungicides at 2-to-3-week intervals throughout the growing season. Besides disease-related yield loss, application of fungicides can result in considerable cost and increases the likelihood of fungicide resistance developing in the pathogen. Resistant cultivars are available for pecan growers; although, in several cases resistance has been overcome as the pathogen adapts to infect resistant hosts. Despite the importance of host resistance in scab management, there is little information regarding the molecular basis of genetic resistance to pecan scab.The purpose of this study was to elucidate mechanisms of natural pecan scab resistance by analyzing transcripts that are differentially expressed in pecan leaf samples from scab resistant and susceptible trees. The leaf samples were collected from trees in a provenance collection orchard that represents the natural range of pecan in the US and Mexico. Trees in the orchard have been exposed to natural scab infections since planting in 1989, and scab ratings were collected over three seasons. Based on this data, ten susceptible trees and ten resistant trees were selected for analysis. RNA-seq data was collected and analyzed for diseased and non-diseased parts of susceptible trees as well as for resistant trees. A total of 313 genes were found to be differentially expressed when comparing resistant and susceptible trees without disease. For susceptible samples showing scab symptoms, 1,454 genes were identified as differentially expressed compared to non-diseased susceptible samples. Many genes involved in pathogen recognition, defense responses, and signal transduction were up-regulated in diseased samples of susceptible trees, whereas differentially expressed genes in pecan scab resistant samples were generally down-regulated compared to non-diseased susceptible samples.Our results provide the first account of candidate genes involved in resistance/susceptibility to pecan scab under natural conditions in a pecan orchard. This information can be used to aid pecan breeding programs and development of biotechnology-based approaches for generating pecan cultivars with more durable scab resistance.

Exposure levels and health implications of fungicides, neonicotinoid insecticides, triazine herbicides and their associated metabolites in pregnant women and men

Exposure to pesticides can pose a series of advance effects on human health. However, the exposure levels and health implications of the current use pesticides and their metabolites in both men and pregnant women remain unclear. In this study, an analytical method was developed to quantify fungicides, neonicotinoid insecticides, triazine herbicides, and their metabolites in the human serum. Fifty of the 73 target pesticides and metabolites were detected in the human serum of men and pregnant women from Wuxi, China, which included 11 triazine herbicides and metabolites, 17 neonicotinoid insecticides and metabolites, and 22 fungicides. Fungicides had the highest cumulative concentration (49.5 ng/mL), followed by neonicotinoid insecticides and metabolites (6.38 ng/mL), and triazine herbicides and metabolites (5.10 ng/mL). Moreover, the estimated daily intake (EDI) of fungicides was 10.4 and 12.7 times higher than that of triazine herbicides (included their metabolites) and neonicotinoid insecticides (included their metabolites), respectively. Of the three categories of pesticides, exposure to fungicides contributed to the highest exposure risk within the hazard quotient in the range of 5.1 × 10-3-0.17. Correlation analysis revealed that the pesticide exposure levels in human serum were correlated with their maximum residue levels in vegetables and fruits. Pesticide exposure has also been correlated with the weight and Body Mass Index (BMI) of humans based on structural equation modeling. This study provides new insights into the exposure of men and pregnant women to a cocktail of fungicides, neonicotinoid insecticides, triazine herbicides and their metabolites.

Architecture and potential roles of a delta-class glutathione S-transferase in protecting honey bee from agrochemicals

The European honey bee, Apis mellifera, serves as the principle managed pollinator species globally. In recent decades, honey bee populations have been facing serious health threats from combined biotic and abiotic stressors, including diseases, limited nutrition, and agrochemical exposure. Understanding the molecular mechanisms underlying xenobiotic adaptation of A. mellifera is critical, considering its extensive exposure to phytochemicals and agrochemicals present in the environment. In this study, we conducted a comprehensive structural and functional characterization of AmGSTD1, a delta class glutathione S-transferase (GST), to unravel its roles in agrochemical detoxification and antioxidative stress responses. We determined the 3-dimensional (3D) structure of a honey bee GST using protein crystallography for the first time, providing new insights into its molecular structure. Our investigations revealed that AmGSTD1 metabolizes model substrates, including 1-chloro-2,4-dinitrobenzene (CDNB), p-nitrophenyl acetate (PNA), phenylethyl isothiocyanate (PEITC), propyl isothiocyanate (PITC), and the oxidation byproduct 4-hydroxynonenal (HNE). Moreover, we discovered that AmGSTD1 exhibits binding affinity with the fluorophore 8-Anilinonaphthalene-1-sulfonic acid (ANS), which can be inhibited with various herbicides, fungicides, insecticides, and their metabolites. These findings highlight the potential contribution of AmGSTD1 in safeguarding honey bee health against various agrochemicals, while also mitigating oxidative stress resulting from exposure to these substances.

A novel 2D-GO@WS2 electrochemical platform for the determination of thiram fungicide

In this paper, the determination of Thiram fungicide by a novel modified screen-printed carbon electrode (SPCE) fabricated modifying the working electrode (WE) with 2D-GO/WS2 nanohybrid composites, is reported. Scanning electron microscopy (SEM), Raman spectroscopy, and fluorescence analysis (PL) were used to reveal the morphological and microstructural characteristics of the 2D-GO/WS2 nanohybrids with different graphene oxide:tungsten disulphide (GO:WS2) ratio. Electrochemical characterization demonstrated that the 2D-WS2/GO nanohybrids having a GO:WS2 ratio = 2:1 shows the highest electrocatalytic activity towards oxidation of Thiram. The developed sensor permits the quantification of Thiram in the linear range 0.083-0.33 µM with a limit of detection (LOD) of 0.02 µM, which is below the legal limits for this fungicide in drinking water or foods.

Mefentrifluconazole-Resistant Risk and Resistance-Related Point Mutation in FpCYP51B of Fusarium pseudograminearum

Mefentrifluconazole, a triazole fungicide, exhibits remarkable efficacy in combating Fusarium spp. The mean EC50 value of mefentrifluconazole against 124 isolates of Fusarium pseudograminearum was determined to be 1.06 μg/mL in this study. Fungicide taming produced five mefentrifluconazole-resistant mutants with resistance factors ranging from 19.21 to 111.34. Compared to the original parental isolates, the fitness of three resistant mutants was much lower, while the remaining two mutants displayed enhanced survival fitness. There was evidence of positive cross-resistance between tebuconazole and mefentrifluconazole. Mefentrifluconazole resistance in F. pseudograminearum can be conferred by FpCYP51BL144F, which was identified in four mutants according to molecular docking and site-directed transformation experiments. Overexpression of FpCYP51s was also detected in the resistant mutants. In conclusion, mefentrifluconazole has a low-to-medium resistance risk in F. pseudograminearum, and the L144F mutation in FpCYP51B and the increased expression level of FpCYP51s may be responsible for mefentrifluconazole resistance in F. pseudograminearum.

Heavy metal status in cocoa (Theobroma cacao L.) soils and beans: the case of Abuakwa North Municipality of Eastern Region, Ghana

In recent times, public concerns over the potential accumulation of heavy metals in agricultural soils and crops due to the excessive use of agrochemicals are increasing. This study was conducted in the Abuakwa North Municipality of Eastern Region, Ghana, to assess the status of heavy metals in cocoa soils and beans. Cocoa farms aged between 10 and 20 years and have received agrochemicals for at least 5 years were selected, and their adjacent forests were used as controls. Soil samples and cocoa pods were collected randomly and processed for laboratory analysis. The study discovered that across the sampling sites, heavy metal concentrations in soil were below permissible limits. However, contamination factor and geo-accumulation index results revealed that Tontro cocoa farms were considerably contaminated and moderately polluted respectively with Cu, probably due to long-term fungicide application. The concentrations of Fe (39.3-47.1 mg kg-1) and Zn (54.8-70.0 mg kg-1) in the cocoa beans across the communities were below the FAO/WHO's safe limit of 99.4 mg kg-1 and 73.0 mg kg-1 respectively. Lead (0.03-0.06 mg kg-1) and Cd (0.12-0.20 mg kg-1) concentrations were below the EU's maximum allowable level and Codex Alimentarius Commission's limit of 1.0 mg kg-1 respectively. However, bean Cu content in the Tontro farm (51.5 mg kg-1) was slightly above the EU's recommended maximum limit of 50.0 mg kg-1, possibly due to the continuous application of copper-based fungicides. The study showed that, overall, agrochemicals used for cocoa farming in Abuakwa North Municipality of Ghana did not cause serious harm to the soils and beans, since the mean metal concentrations were not alarming and guarantee public health safety.

Silver nanoparticles improve the fungicidal properties of Rhazya stricta decne aqueous extract against plant pathogens

One of the most promising, non-toxic, and biocompatible developments for many biological activities is the green synthesis of nanoparticles from plants. In this work, we investigated the antifungal activity of silver nanoparticles (AgNPs) biosynthesized from Rhazya stricta aqueous extract against several plant pathogenic fungi. UV-visible spectroscopy, Zeta potential analysis, Fourier-transform infrared spectroscopy (FTIR), and transmitted electron microscopy (TEM) were used to analyze the biosynthesized AgNPs. Drechslera halodes, Drechslera tetramera, Macrophomina phaseolina, Alternaria alternata, and Curvularia australiensis were tested for their potential antifungal activity. Surface Plasmon Resonance (SPR) of Aq. AgNPs and Alkaline Aq. AgNPs was observed at 405 nm and 415 nm, respectively. FTIR analysis indicated hydroxyl, nitrile, amine, and ketone functional groups. Aq. AgNPs and Alka-line Aq. AgNPs had velocities of - 27.7 mV and - 37.9 mV and sizes of 21-90 nm and 7.2-25.3 nm, respectively, according to zeta potential studies and TEM. The antifungal examination revealed that all species' mycelial development was significantly inhibited, accompanied by severe ultra-structural alterations. Among all treatments, Aq. AgNPs were the most effective fungicide. M. phaseolina was statistically the most resistant, whereas A. alternata was the most vulnerable. To the best of our knowledge, this is the first report on R. stricta's antifungal activity against these species.

Exploring Factors Conditioning the Expression of Botryosphaeria Dieback in Grapevine for Integrated Management of the Disease

Species from the Botryosphaeriaceae family are the causal agents of Botryosphaeria dieback (BD), a worldwide grapevine trunk disease. Because of their lifestyle and their adaptation to a wide range of temperatures, these fungi constitute a serious threat to vineyards and viticulture, especially in the actual context of climate change. Grapevine plants from both nurseries and vineyards are very susceptible to infections by botryosphaeriaceous fungi due to several cuts and wounds made during their propagation process and their entire life cycle, respectively. When decline becomes chronic or apoplectic, it reduces the longevity of the vineyard and affects the quality of the wine, leading to huge economic losses. Given the environmental impact of fungicides, and their short period of effectiveness in protecting pruning wounds, alternative strategies are being developed to fight BD fungal pathogens and limit their propagation. Among them, biological control has been recognized as a promising and sustainable alternative. However, there is still no effective strategy for combating this complex disease, conditioned by both fungal life traits and host tolerance traits, in relationships with the whole microbiome/microbiota. To provide sound guidance for an effective and sustainable integrated management of BD, by combining the limitation of infection risk, tolerant grapevine cultivars, and biological control, this review explores some of the factors conditioning the expression of BD in grapevine. Among them, the lifestyle of BD-associated pathogens, their pathogenicity factors, the cultivar traits of tolerance or susceptibility, and the biocontrol potential of Bacillus spp. and Trichoderma spp. are discussed.

Cloud point extraction of carbendazim fungicide from strawberry samples and amperometric detection with boron doped diamond

The cloud point extraction (Tergitol® surfactant) method was used for the first time to extract and preconcentrate the fungicide carbendazim (CBZ) from strawberry samples, while electrochemical detection (boron doped diamond electrode) in association with high performance liquid chromatography (HPLC-EC) was used for the determination of CBZ. The variables of bath temperature, ultrasonic stirring time, mass of NaCl and amount of surfactant were investigated using a 24 full factorial design. Limits of detection (LOD, S/N = 3) and quantification (LOQ) of 3.42 × 10-8 mol/L (or 6.54 µg/L) and 6.84 × 10-8 mol/L (or 13.1 µg/L), respectively, were obtained for the CPE processes, considering the value of the preconcentration factor obtained (9.12). The method was validated based on linearity, intra-day and inter-day recovery tests, accuracy and precision. The proposed method was applied to strawberry samples from local commercial establishments and different procedures for washing and sanitizing strawberry fruits were also evaluated.

Polyphenols-Rich Extract of Calotropis procera Alone and in Combination with Trichoderma Culture Filtrate for Biocontrol of Cantaloupe Wilt and Root Rot Fungi

Fungal diseases have always been a major problem for cantaloupe crops; however, synthetic fungicides are hazardous to humans and the environment. Consequently, a feasible alternative to fungicides without side effects could be by using bio agents and naturally occurring plants with antibacterial potential. This study has achieved a novel procedure for managing wilt and root rot diseases by potentially using Trichoderma sp. culture filtrates in consortium with plant extract of Calotropis procera, Rhizoctonia solani, Fusarium oxysporum, and Pythium ultimum, which were isolated from infected cantaloupe roots with identified root rot symptoms. The antagonistic activity of four Trichoderma isolates and analysis of antibiotics and filtrate enzymes of the most active Trichoderma isolate were determined as well as phytochemical analysis of C. procera plant extract using HPLC-UV. The obtained results showed that all Trichoderma isolates considerably lowered the radial growth of P. ultimum, R. solani, and F. oxysporum in varying degrees. The scanning electron micrographs illustrate the mycoparasitic nature of Trichoderma sp. on F. oxysporum. The phytochemical analysis of C. procera indicated that phenolic contents were the major compounds found in extracts, such as vanillin (46.79%), chlorogenic acid (30.24%), gallic acid (8.06%), and daidzein (3.45%) but including only a low amount of the flavonoid compounds rutin, naringenin, and hesperetin. The Pot experiment's findings showed that cantaloupe was best protected against wilting and root rot diseases when it was treated with both Trichoderma sp. culture filtrates (10%) and C. procera extract of (15 mg/mL), both alone and in combination. This study demonstrates that the application of bio agent Trichoderma spp. filtrate with C. procera phenol extract appears useful for controlling wilting and root rot disease in cantaloupe. This innovative approach could be used as an alternative to chemical fungicide for the control of wilting and rot root diseases.

Fungi increases kelp (Ecklonia radiata) remineralisation and dissolved organic carbon, alkalinity, and dimethylsulfoniopropionate (DMSP) production

Fungi are key players in terrestrial organic matter (OM) degradation, but little is known about their role in marine environments. Here we compared the degradation of kelp (Ecklonia radiata) in mesocosms with and without fungicides over 45 days. The aim was to improve our understanding of the vital role of fungal OM degradation and remineralisation and its relevance to marine biogeochemical cycles (e.g., carbon, nitrogen, sulfur, or volatile sulfur). In the presence of fungi, 68 % of the kelp detritus degraded over 45 days, resulting in the production of 0.6 mol of dissolved organic carbon (DOC), 0.16 mol of dissolved inorganic carbon (DIC), 0.23 mol of total alkalinity (TA), and 0.076 mol of CO2, which was subsequently emitted to the atmosphere. Conversely, when fungi were inhibited, the bacterial community diversity was reduced, and only 25 % of the kelp detritus degraded over 45 days. The application of fungicides resulted in the generation of an excess amount of 1.5 mol of DOC, but we observed only 0.02 mol of DIC, and 0.04 mol of TA per one mole of kelp detritus, accompanied by a CO2 emission of 0.081 mol. In contrast, without fungi, remineralisation of kelp detritus to DIC, TA, dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP) and methanethiol (MeSH) was significantly reduced. Fungal kelp remineralisation led to a remarkable 100,000 % increase in DMSP production. The observed substantial changes in sediment chemistry when fungi are inhibited highlight the important biogeochemical role of fungal remineralisation, which likely plays a crucial role in defining coastal biogeochemical cycling, blue carbon sequestration, and thus climate regulation.

Assessment of Candidate Reference Genes for Gene Expression Studies Using RT-qPCR in Colletotrichum fructicola from Litchi

Litchi (Litchi chinensis Sonn.) is a tropical fruit originating from southern China that is currently cultivated in subtropical and tropical regions worldwide. Litchi anthracnose, caused by Colletotrichum fructicola, a dominant species of Colletotrichum spp., is an important disease of litchi that damages the fruits in fields and in post-harvest storage. Real-time quantitative PCR (RT-qPCR) is a common technique with which to detect the expression of and function of target genes quickly and precisely, and stable reference genes are crucial. However, there is no comprehensive information on suitable reference genes of C. fructicola present. Here, we designed eight candidate genes (GAPDH, α-tubulin, 18S, β-tubulin, EF1a, TATA, RPS5, and EF3) using RefFinder software (programs: geNorm, ΔCt, BestKeeper, and NormFinder) to investigate their reliability in the detection of C. fructicola under five different treatments (fungal development stage, temperature, UV, culture medium, and fungicide). The results showed the optimal reference genes under different conditions: EF1a and α-tubulin for developmental stage; α-tubulin and β-tubulin for temperature; α-tubulin and RPS5 for UV treatment; RPS5 and α-tubulin for culture medium; α-tubulin, GAPDH, and TATA for fungicide treatments. The corresponding expression patterns of HSP70 (Heat shock protein 70) were significantly different when the most and the least stable reference genes were selected when treated under different conditions. Our study provides the first detailed list of optimal reference genes for the analysis of gene expression in C. fructicola via RT-qPCR, which should be useful for future functional studies of target genes in C. fructicola.

Taxonomy-guided selection of Paraburkholderia busanensis sp. nov.: a versatile biocontrol agent with mycophagy against Colletotrichum scovillei causing pepper anthracnose

IMPORTANCE

Traditional control methods for postharvest diseases rely on fungicides, which cause human health and environmental concerns. This study introduces a taxonomy-guided strategy for selecting biocontrol agents. By focusing on Paraburkholderia group, which harbors diverse plant-beneficial strains, the inadvertent selection of harmful strains was circumvented, thereby obviating the need for laborious in vitro screening assays. A highly promising candidate, strain P39, has been identified, exhibiting remarkable biocontrol activity against Colletotrichum scovillei. Through comprehensive genomic, physiological, and biochemical analyses, P39 was characterized as a novel species within the Paraburkholderia genus and designated Paraburkholderia busanensis. Moreover, these findings deepen our understanding of bacterial-fungal interactions, as they elucidate a potential pathway for the utilization of fungal chitin, thereby enhancing our understanding of bacterial mycophagy. P. busanensis is a promising source of antifungal volatiles and putative novel secondary metabolites.

Double-stranded RNA prevents and cures infection by rust fungi

Fungal pathogens that impact perennial plants or natural ecosystems require management strategies beyond fungicides and breeding for resistance. Rust fungi, some of the most economically and environmentally important plant pathogens, have shown amenability to double-stranded RNA (dsRNA) mediated control. To date, dsRNA treatments have been applied prior to infection or together with the inoculum. Here we show that a dsRNA spray can effectively prevent and cure infection by Austropuccinia psidii (cause of myrtle rust) at different stages of the disease cycle. Significant reductions in disease coverage were observed in plants treated with dsRNA targeting essential fungal genes 48 h pre-infection through to 14 days post-infection. For curative treatments, improvements in plant health and photosynthetic capacity were seen 2-6 weeks post-infection. Two-photon microscopy suggests inhibitory activity of dsRNA on intercellular hyphae or haustoria. Our results show that dsRNA acts both preventively and curatively against myrtle rust disease, with treated plants recovering from severe infection. These findings have immediate potential in the management of the more than 10-year epidemic of myrtle rust in Australia.

Protecting-group free synthesis of glycoconjugates displaying dual fungicidal and plant defense-eliciting activities

A straightforward synthesis of carbohydrate templated isoxazolidines is described, by reaction of unprotected glycosylhydroxylamines (operating as 1,3-dipoles) with methyl acrylate using microwave activation. Rhamno- and erythro-isoxazolidines are recognized by plant cells, resulting in a strong ROS-production as a plant immune response, and exert a high antifungal activity against Botrytis cinerea.

New 2,4-dihydro-1H-1,2,4-triazole-3-selones and 3,3'-di(4H-1,2,4-triazolyl)diselenides. Synthesis, biological evaluation, and in silico studies as antibacterial and fungicidal agents

The reaction of aromatic ring-substituted isoselenocyanates with 2-thiopheacetic and 4-pyridinecarboxylic acid hydrazides yielded selenosemicarbazides which were further converted into previously unknown 1,2,4-triazole-3-selones and 3,3'-di(4H-1, 2,4-triazolyl)diselenides. The structures of the obtained compounds were studied by NMR spectroscopy, IR spectroscopy, and high-resolution mass spectroscopy (HR-MS). The bactericidal and fungicidal activity of some obtained compounds was evaluated in molecular modeling studies such as docking and simulation studies. The compound 3ba was reported as the most promising compound to show robust binding energy with different antibacterial and antifungal compounds. The compounds were observed in strong hydrophilic and hydrophobic interactions and remained in stable binding conformation with the receptor enzymes. Furthermore, the interatomic interaction energies were dominated by Van der Waals and electrostatic energies indicating the formation of stable complexes.

Intensive vegetable production under plastic mulch: A field study on soil plastic and pesticide residues and their effects on the soil microbiome

Intensive agriculture relies on external inputs to reach high productivity and profitability. Plastic mulch, mainly in the form of Low-Density Polyethylene (LDPE), is widely used in agriculture to decrease evaporation, increase soil temperature and prevent weeds. The incomplete removal of LDPE mulch after use causes plastic contamination in agricultural soils. In conventional agriculture, the use of pesticides also leaves residues accumulating in soils. Thus, the objective of this study was to measure plastic and pesticide residues in agricultural soils and their effects on the soil microbiome. For this, we sampled soil (0-10 cm and 10-30 cm) from 18 parcels from 6 vegetable farms in SE Spain. The farms were under either organic or conventional management, where plastic mulch had been used for >25 years. We measured the macro- and micro-light density plastic debris contents, the pesticide residue levels, and a range of physiochemical properties. We also carried out DNA sequencing on the soil fungal and bacterial communities. Plastic debris (>100 μm) was found in all samples with an average number of 2 × 103 particles kg-1 and area of 60 cm2 kg-1. We found 4-10 different pesticide residues in all conventional soils, for an average of 140 μg kg-1. Overall, pesticide content was ∼100 times lower in organic farms. The soil microbiomes were farm-specific and related to different soil physicochemical parameters and contaminants. Regarding contaminants, bacterial communities responded to the total pesticide residues, the fungicide Azoxystrobin and the insecticide Chlorantraniliprole as well as the plastic area. The fungicide Boscalid was the only contaminant to influence the fungal community. The wide spread of plastic and pesticide residues in agricultural soil and their effects on soil microbial communities may impact crop production and other environmental services. More studies are required to evaluate the total costs of intensive agriculture.

Occurrence of Aspergillus fumigatus azole resistance in soils from Switzerland

Aspergillus fumigatus is a fungal species causing diverse diseases in humans. The use of azoles for treatments of A. fumigatus diseases has resulted in azole resistance. Azoles are also widely used in the environment for crop protection, which resulted in azole resistance. Resistance is primarily due to mutations in cyp51A, which encodes the target protein for azoles. Here we addressed the occurrence of azole resistance in soils from a vast part of Switzerland. We aimed to associate the use of azoles in the environment with the occurrence of azole resistance. We targeted sample sites from different agricultural environments as well as sites with no agricultural practice (natural sites and urban sites). Starting from 327 sites, 113 A. fumigatus isolates were recovered (2019-2021), among which 19 were azole-resistant (15 with TR34/L98H and four with TR46/Y121F/T289A resistance mutations in cyp51A). Our results show that azole resistance was not associated with a specific agricultural practice. Azoles could be chemically detected in investigated soils, however, their presence was not associated with the occurrence of azole-resistant isolates. Interestingly, genetic markers of resistance to other fungicides were detected but only in azole-resistant isolates, thus reinforcing the notion that A. fumigatus cross-resistance to fungicides has an environmental origin. In conclusion, this study reveals the spreading of azole resistance in A. fumigatus from the environment in Switzerland. The proximity of agricultural areas to urban centers may facilitate the transmission of resistant strains to at-risk populations. Thus, vigilant surveillance is required to maintain effective treatment options for aspergillosis.

A Loop-Mediated Isothermal Amplification Assay for the Identification of Botrytis fragariae in Strawberry

Gray mold in strawberry is caused by multiple species of Botrytis, including Botrytis cinerea, B. pseudocinerea, B. fragariae, and B. mali. The species B. cinerea and B. fragariae are widespread in production regions of the eastern United States and Germany, and their distinction is important for disease management strategies. Currently, the only way to differentiate these species in field samples is by PCR, which is time consuming, labor intensive, and costly. In this study, a loop-mediated isothermal amplification (LAMP) technique was developed based on species-specific NEP2 gene nucleotide sequences. The designed primer set specifically amplified B. fragariae DNA and no other Botrytis spp. (B. cinerea, B. mali, and B. pseudocinerea) or plant pathogens. The LAMP assay was able to amplify fragments from DNA extracted from infected fruit using a rapid DNA extraction protocol, confirming its ability to detect low amounts of B. fragaria DNA from field-infected fruit. In addition, a blind test was performed to identify B. fragariae in 51 samples collected from strawberry fields in the eastern United States using the LAMP technique. The B. fragariae samples were identified with a reliability of 93.5% (29 of 32), and none of the B. cinerea, B. pseudocinerea, or B. mali samples included in the test were amplified in 10 min. Our results show that the LAMP technique is a specific and reliable method for the detection of B. fragariae from infected fruit tissue and can help to control this important disease in the field.

Meta-Analytic Modeling of the Severity-Yield Relationships in Soybean Frogeye Leaf Spot Epidemics

Frogeye leaf spot (FLS), caused by Cercospora sojina, is an important foliar disease affecting soybean in the United States. A meta-analytic approach including 39 fungicide trials conducted from 2012 to 2021 across eight states (Alabama, Arkansas, Illinois, Iowa, Kentucky, Louisiana, Mississippi, Tennessee) was used to assess the relationship between FLS severity and soybean yield. Correlation and regression analyses were performed separately to determine Fisher's transformation of correlation coefficients (Zr), intercept (β0) and slope (β1). Disease pressure (low severity, ≤34.5; high severity, >34.5%) and yield class (low, ≤3,352; high, >3,352 kg/ha) were included as categorical moderators. Pearson's [Formula: see text], obtained from back-transforming the [Formula: see text]r estimated by an overall random-effects model, showed a significant negative linear relationship between FLS severity and yield ([Formula: see text] = -0.60). The [Formula: see text]r was affected by disease pressure (P = 0.0003) but not by yield class (P = 0.8141). A random-coefficient model estimated a slope of -19 kg/ha for each percent severity for a mean attainable yield of 3,719.9 kg/ha. Based on the overall mean (95% CI) of the intercept and slope estimated by the random-coefficients model, the estimated overall relative damage coefficient was 0.51% (0.36 to 0.69), indicating that a percent increase in FLS severity reduced yield by 0.51%. The best model included yield class as a covariate, and population-average intercepts differed significantly between low (3,455.1 kg/ha) and high (3,842.7 kg/ha) yield classes. This highlights the potential impact of FLS on soybean yield if not managed and may help in disease management decisions.

Major Fusarium species and mycotoxins associated with freshly harvested maize grain in Uruguay

Fusarium species are common fungal pathogens of maize. Fusarium graminearum and Fusarium verticillioides, among others, can cause maize ear rot, and they are also mycotoxin producers. The aims of this work were to determine the frequency and diversity of Fusarium species in Uruguayan maize kernels, evaluate the toxigenic potential of the isolates, determine toxin contamination levels on freshly harvested grain, and assess the sensitivity of main Fusarium species against fungicides. Fusarium verticillioides was the most frequent species isolated, followed by Fusarium graminearum sensu stricto. Of F. verticillioides isolates studied for fumonisin production, 72% produced fumonisin B1 and 32% fumonisin B2. Considering in vitro toxin production by F. graminearum sensu stricto isolates, deoxynivalenol was the main toxin produced, followed by zearalenone and nivalenol. Fumonisins were the most frequently found toxins on freshly harvested maize samples (98% in 2018 and 86% in 2019), and also, fumonisin B1 was the toxin with highest concentration in both years studied (4860 µg/kg in 2018 and 1453 µg/kg in 2019). Deoxynivalenol and zearalenone were also found as contaminants. Metconazole and epoxiconazole were the most effective fungicides tested on F. verticillioides isolates. Fusarium graminearum sensu stricto isolates also were more sensitive to metconazole compared to other fungicides; nevertheless, epoxiconazole was less efficient in controlling this species. This is the first study that reports Fusarium species and mycotoxin contamination levels associated with maize grain in Uruguay. Its detection is the main step to develop management strategies in order to minimize fungal infection in maize crops.

Disease decreases variation in host community structure in an old-field grassland

Disease may drive variation in host community structure by modifying the interplay of deterministic and stochastic processes that shape communities. For instance, deterministic processes like ecological selection can benefit species less impacted by disease. When communities have higher levels of disease and disease consistently selects for certain host species, this can reduce variation in host community composition. On the other hand, when host communities are less impacted by disease and selection is weaker, stochastic processes (e.g., drift, dispersal) may play a bigger role in host community structure, which can increase variation among communities. While effects of disease on host community structure have been quantified in field experiments, few have addressed the role of disease in modulating variation in structure among host communities. To address this, we conducted a field experiment spanning three years, using a tractable system: foliar fungal pathogens in an old-field grassland community dominated by the grass Lolium arundinaceum, tall fescue. We reduced foliar fungal disease burden in replicate host communities (experimental plots in intact vegetation) in three fungicide regimens that varied in the seasonal duration of fungicide treatment and included a fungicide-free control. We measured host diversity, biomass, and variation in community structure among replicate communities. Disease reduction generally decreased plant richness and increased aboveground biomass relative to communities experiencing ambient levels of disease. These changes in richness and aboveground biomass were consistent across years despite changes in structure of the plant communities over the experiment's three years. Importantly, disease reduction amplified host community variation, suggesting that disease diminished the degree to which host communities were structured by stochastic processes. These results of experimental disease reduction both highlight the potential importance of stochastic processes in plant communities and reveal the potential for disease to regulate variation in host community structure.

Honey bees and bumble bees may be exposed to pesticides differently when foraging on agricultural areas

In an agricultural environment, where crops are treated with pesticides, bees are likely to be exposed to a range of chemical compounds in a variety of ways. The extent to which different bee species are affected by these chemicals, largely depends on the concentrations and type of exposure. We quantified the presence of selected pesticide compounds in the pollen of two different entomophilous crops; oilseed rape (Brassica napus) and broad bean (Vicia faba). Sampling was performed in 12 sites in Ireland and our results were compared with the pollen loads of honey bees and bumble bees actively foraging on those crops in those same sites. Detections were compound specific, and the timing of pesticide application in relation to sampling likely influenced the final residue contamination levels. Most detections originated from compounds that were not recently applied on the fields, and samples from B. napus fields were more contaminated compared to those from V. faba fields. Crop pollen was contaminated only with fungicides, honey bee pollen loads contained mainly fungicides, while more insecticides were detected in bumble bee pollen loads. The highest number of compounds and most detections were observed in bumble bee pollen loads, where notably, all five neonicotinoids assessed (acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam) were detected despite the no recent application of these compounds on the fields where samples were collected. The concentrations of neonicotinoid insecticides were positively correlated with the number of wild plant species present in the bumble bee-collected pollen samples, but this relationship could not be verified for honey bees. The compounds azoxystrobin, boscalid and thiamethoxam formed the most common pesticide combination in pollen. Our results raise concerns about potential long-term bee exposure to multiple residues and question whether honey bees are suitable surrogates for pesticide risk assessments for all bee species.

Moving past neonicotinoids and honeybees: A systematic review of existing research on other insecticides and bees

Synthetic pesticides (e.g. herbicides, fungicides and insecticides) are used widely in agriculture to protect crops from pests, weeds and disease. However, their use also comes with a range of environmental concerns. One key concern is the effect of insecticides on non-target organisms such as bees, who provide pollination services for crops and wild plants. This systematic literature review quantifies the existing research on bees and insecticides broadly, and then focuses more specifically on non-neonicotinoid insecticides and non-honeybees. We find that articles on honeybees (Apis sp.) and insecticides account for 80% of all research, with all other bees combined making up 20%. Neonicotinoids were studied in 34% of articles across all bees and were the most widely studied insecticide class for non-honeybees overall, with almost three times as many studies than the second most studied class. Of non-neonicotinoid insecticide classes and non-honeybees, the most studied were pyrethroids and organophosphates followed by carbamates, and the most widely represented bee taxa were bumblebees (Bombus), followed by leaf-cutter bees (Megachile) and mason bees (Osmia). Research has taken place across several countries, with the highest numbers of articles from Brazil and the US, and with notable gaps from countries in Asia, Africa and Oceania. Mortality was the most studied effect type, while sub-lethal effects such as on behaviour were less studied. Few studies tested how the effect of insecticides were influenced by multiple pressures, such as climate change and co-occurring pesticides (cocktail effects). As anthropogenic pressures do not occur in isolation, we suggest that future research also addresses these knowledge gaps. Given the changing global patterns in insecticide use, and the increasing inclusion of both non-honeybees and sub-lethal effects in pesticide risk assessment, there is a need for expanding research beyond its current state to ensure a strong scientific evidence base for the development of risk assessment and associated policy.

Selection and Validation of Reference Genes for Reverse-Transcription Quantitative PCR Analysis in Sclerotium rolfsii

Reference genes are important for the accuracy of gene expression profiles using reverse-transcription quantitative PCR (RT-qPCR). However, there are no available reference genes reported for Sclerotium rolfsii; it actually has a pretty diverse and wide host range. In this study, seven candidate reference genes (UBC, β-TUB, 28S, 18S, PGK, EF1α and GAPDH) were validated for their expression stability in S. rolfsii under conditions of different developmental stages, populations, fungicide treatments, photoperiods and pHs. Four algorithm programs (geNorm, Normfinder, Bestkeeper and ΔCt) were used to evaluate the gene expression stability, and RefFinder was used to integrate the ranking results of four programs. Two reference genes were recommended by RefFinder for RT-qPCR normalization in S. rolfsii. The suitable reference genes were GAPDH and UBC across developmental stages, PGK and UBC across populations, GAPDH and PGK across fungicide treatments, EF1α and PGK across photoperiods, β-TUB and EF1α across pHs and PGK and GAPDH across all samples. Four target genes (atrB, PacC, WC1 and CAT) were selected for the validation of the suitability of selected reference genes. However, using one or two reference genes in combination to normalize the expression of target genes showed no significant difference in S. rolfsii. In short, this study provided reliable reference genes for studying the expression and function of genes in S. rolfsii.

Evaluation of a high-throughput H295R homogenous time resolved fluorescence assay for androgen and estrogen steroidogenesis screening

The H295R test guideline assay evaluates the effect of test substances on synthesis of 17β-estradiol (E2) and testosterone (T). The objective of this study was to leverage commercial immunoassay technology to develop a more efficient H295R assay to measure E2 and T levels in 384-well format. The resulting Homogenous Time Resolved Fluorescence assay platform (H295R-HTRF) was evaluated against a training set of 36 chemicals derived from the OECD inter-laboratory validation study, EPA guideline 890.1200 aromatase assay, and azole fungicides active in the HT-H295R assay. Quality control performance criteria were met for all conditions except E2 synthesis inhibition where low basal hormone synthesis was observed. Five proficiency chemicals were active for both the E2 and T endpoints, consistent with guideline classifications. Of the nine OECD core reference chemicals, 9/9 were concordant with outcomes for E2 and 7/9 for T. Likewise, 9/13 and 11/13 OECD supplemental chemicals were concordant with anticipated effects for E2 and T, respectively. Of the 10 azole fungicides screened, 7/10 for E2 and 8/10 for T exhibited concordant outcomes for inhibition. Generally, all active chemicals in the training set demonstrated equivalent or greater potency in the H295R-HTRF assay, supporting the sensitivity of the platform. The adaptation of HTRF technology to the H295R model provides an efficient way to evaluate E2 and T modulators in accordance with guideline specifications.

Advances in understanding the mechanism of resistance to anthracnose and induced defence response in tea plants

The tea plant (Camellia sinensis) is susceptible to anthracnose disease that causes considerable crop loss and affects the yield and quality of tea. Multiple Colletotrichum spp. are the causative agents of this disease, which spreads quickly in warm and humid climates. During plant-pathogen interactions, resistant cultivars defend themselves against the hemibiotrophic pathogen by activating defence signalling pathways, whereas the pathogen suppresses plant defences in susceptible varieties. Various fungicides have been used to control this disease on susceptible plants, but these fungicide residues are dangerous to human health and cause fungicide resistance in pathogens. The problem-solving approaches to date are the development of resistant cultivars and ecofriendly biocontrol strategies to achieve sustainable tea cultivation and production. Understanding the infection stages of Colletotrichum, tea plant resistance mechanisms, and induced plant defence against Colletotrichum is essential to support sustainable disease management practices in the field. This review therefore summarizes the current knowledge of the identified causative agent of tea plant anthracnose, the infection strategies and pathogenicity of C. gloeosporioides, anthracnose disease resistance mechanisms, and the caffeine-induced defence response against Colletotrichum infection. The information reported in this review will advance our understanding of host-pathogen interactions and eventually help us to develop new disease control strategies.