Yunlong Yu

Chiral pesticides often exhibit an enantioselective environmental behavior and ecological effects. Using a soil-earthworm microcosm, we investigated the dissipation and bioaccumulation of metalaxyl enantiomers and their effects on gut microbiota and antibiotic resistance genes (ARGs). R-metalaxyl dissipated rapidly (half-life 7–9 d), whereas S-metalaxyl persisted much longer (about 90 d), imposing prolonged selective pressure. Earthworms preferentially accumulated R-metalaxyl, with a maximum bioaccumulation factor of 0.42. High-concentration S-metalaxyl increased the total ARG abundance in earthworm guts by approximately 35% relative to the control. Antioxidant enzyme activities showed an enantioselective pattern of initial stimulation followed by decline over time. Metalaxyl increased Streptococcus abundance by 1–3% and reduced sensitive genera, while R-metalaxyl selectively enriched rifamycin-, multidrug-, and glycopeptide-resistance genes. Over 60% of ARGs co-occurred with plasmids, indicating an elevated horizontal gene transfer risk. These results confirm significant enantioselective effects of metalaxyl on dissipation, enrichment, microbiome structure, and antibiotic resistance transmission in earthworm guts.

This study investigates the combined effects of polystyrene nanoplastics (PS-NPs) and deltamethrin (DEL) on mice, focusing on their different impacts among organs. Mice were exposed to PS-NPs and/or DEL for 30 days. Results showed that PS-NPs alleviated DEL-induced oxidative damage in the liver and kidney by reducing its accumulation due to decreased bioaccessibility. Conversely, PS-NPs increased DEL accumulation in the intestine, leading to enhanced susceptibility to enteric infections caused by bacteria, viruses, and parasites, as indicated by transcriptomic analysis. PS-NPs delayed DEL excretion by reducing gastrointestinal motility, as evidenced by altered neurotransmitter levels, thereby contributing to greater intestinal accumulation of DEL. Moreover, 16S rDNA sequencing revealed that PS-NPs tended to decrease beneficial bacteria and increase pathogenic bacteria in the gut microbiota, further heightening susceptibility to enteric infections upon coexposure. The findings of this study shed new light on the complex health risks associated with coexposure to nanoplastics and pesticides.

From a "One Health" perspective, the global threat of antibiotic resistance genes (ARGs) is associated with modern agriculture practices including agrochemicals application. Chiral fungicides account for a considerable proportion of wildly used agrochemicals; however, whether and how their enantiomers lead to differential proliferation of antibiotic resistance in agricultural environments remain overlooked. Focused on the soil-earthworm ecosystem, we for the first time deciphered the mechanisms underlying the enantioselective proliferation of antibiotic resistance driven by the enantiomers of a typical chiral fungicide mandipropamid (i.e., R-MDP and S-MDP) utilizing a multiomic approach. Time-series metagenomic analysis revealed that R-MDP led to a significant enhancement of ARGs with potential mobility (particularly the plasmid-borne ARGs) in the earthworm intestinal microbiome. We further demonstrated that R-MDP induced a concentration-dependent facilitation of plasmid-mediated ARG transfer among microbes. In addition, transcriptomic analysis with verification identified the key aspects involved, where R-MDP enhanced cell membrane permeability, transfer ability, biofilm formation and quorum sensing, rebalanced energy production, and decreased cell mobility versus S-MDP. Overall, the findings provide novel insights into the enantioselective disruption of microbiome and resistome in earthworm gut by chiral fungicides and offer significant contributions to the comprehensive risk assessment of chiral agrochemicals in agroecosystems.

BACKGROUND: The insecticide carbosulfan is usually applied as a soil treatment or seed‐coating agent, and so may be absorbed by crops and pose dietary risks. Understanding the uptake, metabolism and translocation of carbosulfan in crops is conducive to its safe application. In this study, we investigated the distribution of carbosulfan and its toxic metabolites in maize plants at both the tissue and subcellular levels, and explored the uptake and translocation mechanism of carbosulfan.RESULTS: Carbosulfan was mainly taken up by maize roots via the apoplast pathway, was preferentially distributed in cell walls (51.2%–57.0%) and most (85.0%) accumulated in roots with only weak upward translocation. Carbofuran, the main metabolite of carbosulfan in maize plants, was primarily stored in roots. However, carbofuran could be upwardly translocated to shoots and leaves because of its greater distribution in root‐soluble components (24.4%–28.5%) compared with carbosulfan (9.7%–14.5%). This resulted from its greater solubility compared with its parent compound. The metabolite 3‐hydroxycarbofuran was found in shoots and leaves.CONCLUSION: Carbosulfan could be passively absorbed by maize roots, mainly via the apoplastic pathway, and transformed into carbofuran and 3‐hydroxycarbofuran. Although carbosulfan mostly accumulated in roots, its toxic metabolites carbofuran and 3‐hydroxycarbofuran could be detected in shoots and leaves. This implies that there is a risk in the use of carbosulfan as a soil treatment or seed coating. © 2023 Society of Chemical Industry.

BACKGROUND: Triazole resistance in the human fungal pathogen Aspergillus fumigatus has been a growing challenge in clinic treatment with triazole drugs such as itraconazole. The fast evolvement of triazole resistance in A. fumigatus in the ecosystem has drawn great attention, and there has been a possible link between the application of triazole fungicides in agriculture and triazole resistance in A . fumigatus. The change in susceptibility of A . fumigatus exposed to the new chiral triazole fungicide mefentrifluconazole was investigated in this study. RESULTS: The results indicated that triazole resistance in A. fumigatus was acquired with exposure to mefentrifluconazole at a level of greater than or equal to 2 mg L ⁻¹ in liquid medium and soil (not at 0.4 nor 1 mg L ⁻¹ ). Interestingly, stereoselectivity was found in the acquisition of triazole resistance in A. fumigatus when exposed to mefentrifluconazole. R‐mefentrifluconazole, which is very active on plant pathogens, exhibited stronger possibility in the development of the resistance in A. fumigatus than its antipode. Overexpression of cyp51A , AtrF , AfuMDR1 and AfuMDR4 were associated with the acquired resistance in A. fumigatus with hereditary stability. CONCLUSION: The results suggest that triazole resistance in A. fumigatus could be resulted from the selection of mefentrifluconazole at concentrations larger than 2 mg L ⁻¹ . Mefentrifluconazole should be applied within the dosage recommended by good agricultural practice to avoid the resistance in A. fumigatus in soil. This also may be applicable to other triazole fungicides. © 2022 Society of Chemical Industry.

Plant-pathogenic fungi form intimate interactions with their associated bacterial microbiota during their entire life cycle. However, little is known about the structure, functions and interaction mechanisms of bacterial communities associated with fungal fruiting bodies (perithecia). Here we examined the bacterial microbiome of perithecia formed by Fusarium graminearum, the major pathogenic fungus causing Fusarium head blight in cereals. A total of 111 shared bacterial taxa were identified in the microbiome of 65 perithecium samples collected from 13 geographic locations. Within a representative culture collection, 113 isolates exhibited antagonistic activity against F. graminearum, with Pantoea agglomerans ZJU23 being the most efficient in reducing fungal growth and infectivity. Herbicolin A was identified as the key antifungal compound secreted by ZJU23. Genetic and chemical approaches led to the discovery of its biosynthetic gene cluster. Herbicolin A showed potent in vitro and in planta efficacy towards various fungal pathogens and fungicide-resistant isolates, and exerted a fungus-specific mode of action by directly binding and disrupting ergosterol-containing lipid rafts. Furthermore, herbicolin A exhibited substantially higher activity (between 5- and 141-fold higher) against the human opportunistic fungal pathogens Aspergillus fumigatus and Candida albicans in comparison with the clinically used fungicides amphotericin B and fluconazole. Its mode of action, which is distinct from that of other antifungal drugs, and its efficacy make herbicolin A a promising antifungal drug to combat devastating fungal pathogens, both in agricultural and clinical settings.

BACKGROUND: The efficacy of a herbicide as soil treatment agent may be largely affected by soil characteristics. Understanding the relationship between herbicide efficacy and soil characteristics can provide decision basis for herbicide application according to local conditions. This study was aimed towards exploring the effect of soil characteristics on herbicidal activity of atrazine as a model herbicide to barnyard grass and thus to find an indicator for the herbicidal activity assessment of a herbicide against weeds.RESULTS: The herbicidal activity of atrazine to barnyard grass varied greatly among the tested soils with the medium inhibition concentration (IC₅₀), based on the amended concentration, ranging from 1.07 to 10.91 mg kg⁻¹. Uptake of atrazine by barnyard grass was negatively correlated with its adsorption onto soils, whereas it was positively related to the concentration of the herbicide in in situ pore water (C_IPW). Comparable IC₅₀ values ranging from 1.14 to 1.38 were obtained from C_IPW in the tested soils with much smaller variation coefficient compared to those based on the traditional concentration (C_soil) of this herbicide in soils determined by extraction with organic solvents.CONCLUSION: The concentration of atrazine in in situ pore water could be reliable to evaluate its bioavailability and herbicidal activity to barnyard grass. C_IPW of a herbicide in soil could be an indicator for guiding the practical application rate. © 2022 Society of Chemical Industry.