Glufosinate-ammonium: a review of the current state of knowledge

Forensic toxicological studies of acute glufosinate poisoning: A case series

Glufosinate is a widely and increasingly used non-selective, broad-spectrum herbicide. Although cases of glufosinate poisoning are frequently reported, they are rarely documented in forensic case reports, particularly in fatal instances. The present study examined six cases of glufosinate poisoning, including a fatal case involving a 25-year-old female found deceased by the roadside, with an empty 1000 mL bottle labeled "glufosinate" by her side. Biological specimens such as plasma or cardiac blood, gastric contents, and liver tissues were collected for quantitative analysis of glufosinate levels using LC-MS/MS. In five cases of acute glufosinate poisoning, glufosinate plasma concentrations ranged from 0.62 to 3.92 μg/mL. In the fatal case, the concentrations of glufosinate in cardiac blood, gastric contents, and liver tissues were 8.41 μg/mL, 31.25 μg/mL, and 66.1 μg/g, respectively. The pathological autopsy concluded that the cause of death was acute cardio-respiratory failure due to glufosinate poisoning, characterized by multi-organ congestion without specific pathological findings. The toxicological data provided in this study aim to serve as a critical reference for future clinical treatment and forensic validation of glufosinate poisoning-related deaths.

Integrative omics analyses of tea (Camellia sinensis) under glufosinate stress reveal defense mechanisms: A trade-off with flavor loss

Extensively applied glufosinate (GLU) will trigger molecular alterations in nontarget tea plants (Camellia sinensis), which inadvertently disturbs metabolites and finally affects tea quality. The mechanistic response of tea plants to GLU remains unexplored. This study investigated GLU residue behavior, the impact on photosynthetic capacity, specialized metabolites, secondary pathways, and transcript levels in tea seedlings. Here, GLU mainly metabolized to MPP and accumulated more in mature leaves than in tender ones. GLU catastrophically affected photosynthesis, leading to leaf chlorosis, and decreased Fv/Fm and chlorophyll content. Physiological and biochemical, metabolomics, and transcriptomics analyses were integrated. Showing that GLU disrupted the photosynthetic electron transport chain, triggered ROS and antioxidant system, and inhibited photosynthetic carbon fixation. GLU targeted glutamine synthetase (GS) leading to the accumulation of ammonium and the inhibition of key umami L-theanine, causing a disorder in nitrogen metabolism, especially for amino acids synthesis. Interestingly, biosynthesis of primary flavonoids was sacrificed for defensive phenolic acids and lignin formulation, leading to possible losses in nutrition and tenderness in leaves. This study revealed the defense intricacies and potential quality deterioration of tea plants responding to GLU stress. Valuable insights into detoxification mechanisms for non-target crops post-GLU exposure were offered.

Herbicidal proteins from Bacillus wiedmannii isolate ZT selectively inhibit ryegrass (Lolium temulentum L.)

BACKGROUND

The widespread use of chemical herbicides and the growing issue of weed resistance pose significant challenges in agriculture. To address these problems, there is a pressing need to develop biological herbicides based on bacterial metabolites.

RESULTS

In this study, we investigated the impact of the cell-free culture filtrate (CFCF) from the ZT isolate, a bacilliform bacterium obtained from diseased wheat seeds, on the germination and seedling growth of various plant species, including wild oat, ryegrass, redroot, wheat, and chickpea. The results revealed that CFCF had a detrimental effect on the fresh and dry weight of stems and roots in most of the studied plants, except chickpeas. The CFCF was further subjected to separation into aqueous and organic phases using chloroform, followed by the division of the aqueous phase into 13 fractions using an alumina column. Notably, both the aqueous phase (20%) and all 13 fractions (ranging from 50% to 83%) displayed the ability to reduce the root length of ryegrass, a monocotyledonous weed. Liquid chromatography-mass spectrometry (LC-MS) analysis identified that fractions 3 and 7, which were effective against ryegrass but not redroot, contained Cry family proteins, including Cry10 Aa, Cry4 Ba, and Cry4 Aa. Additionally, 16s rRNA gene sequencing revealed that the ZT isolate is closely related (98.27%) to Bacillus wiedmannii.

CONCLUSION

Conclusively, metabolites from the ZT bacterium hold promise for monocotyledonous weed-targeted herbicides, providing a constructive strategy to confront agricultural issues tied to chemical herbicides and weed resistance. © 2024 Society of Chemical Industry.

One-Pot Two-Stage Biocatalytic Cascade to Produce l-Phosphinothricin by Two Enantioselective Complementary Aminotransferases at High Substrate Loading via a Deracemization Process

The bioderacemization of racemic phosphinothricin (D, L-PPT) is a promising route for the synthesis of l-phosphinothricin (L-PPT). However, the low activity and tolerance of wild-type enzymes restrict their industrial applications. Two stereocomplementary aminotransferases with high activity and substrate tolerance were identified in a metagenomic library, and a one-pot, two-stage artificial cascade biocatalytic system was developed to produce L-PPT through kinetic resolution and asymmetric amination. We observed that 500 mM D, L-PPT (100 g/L) could be converted into L-PPT with 94% final conversion and >99.9% enantiomeric excess (e.e.) within 24 h, with only 0.02 eq amino acceptor pyruvate and 1.2 eq amino donor l-aspartate required. The process could be scaled up to 10 L under sufficient oxygen and stirring. The superior catalytic performance of this system provides an eco-friendly and sustainable approach to the industrial deracemization of D, L-PPT to L-PPT.

Sensitive fluorescence detection of glyphosate and glufosinate ammonium pesticides by purine-hydrazone-Cu2+ complex

Organophosphorus pesticides play an important role as broad-spectrum inactivating herbicides in agriculture. Developing a method for rapid and efficient organophosphorus pesticides detection is still urgent due to the increasing concern on food safety. An organo-probe (ZDA), synthesized by purine hydrazone derivative and 2,2'-dipyridylamine derivative, was applied in sensitive recognition of Cu2+ with detection limit of 300 nM. Mechanism study via density functional theory (DFT) and job's plot experiment revealed that ZDA and Cu2+ ions form a 1:2 complex quenching the fluorescence emission. Moreover, this fluorescent complex ZDA-Cu2+ was applicable for detecting glyphosate and glufosinate ammonium following fluorescence enhancement mechanism, with detection limits of 11.26 nM and 11.5 nM, respectively. Meanwhile, ZDA-Cu2+ was effective and sensitive when it is used for pesticide detection, reaching the maximum value and stabilizing in 1 min. Finally, the ZDA-Cu2+ probe could also be tolerated in cell assay environment, implying potential bio-application.

Cellular and Genomic Instability Induced by the Herbicide Glufosinate-Ammonium: An In Vitro and In Vivo Approach

Glufosinate-ammonium (GLA), an organophosphate herbicide, is released at high concentrations in the environment, leading to concerns over its potential genotoxic effects. However, few articles are available in the literature reporting the possible cellular and nuclear effects of this compound. We assessed, by in vitro and in vivo micronucleus assays, the genotoxicity of GLA on cultured human lymphocytes and Lymnaea stagnalis hemocytes at six concentrations: 0.010 (the established acceptable daily intake value), 0.020, 0.050, 0.100, 0.200, and 0.500 µg/mL. In human lymphocytes, our results reveal a significant and concentration-dependent increase in micronuclei frequency at concentrations from 0.100 to 0.500 μg/mL, while in L. stagnalis hemocytes, significant differences were found at 0.200 and 0.500 μg/mL. A significant reduction in the proliferation index was observed at all tested concentrations, with the only exception of 0.010 μg/mL, indicating that the exposure to GLA could lead to increased cytotoxic effects. In L. stagnalis, a significant reduction in laid eggs and body growth was also observed at all concentrations. In conclusion, we provided evidence of the genomic and cellular damage induced by GLA on both cultured human lymphocytes and a model organism's hemocytes; in addition, we also demonstrated its effects on cell proliferation and reproductive health in L. stagnalis.

Chromatographic Methods for the Determination of Glyphosate in Cereals Together with a Discussion of Its Occurrence, Accumulation, Fate, Degradation, and Regulatory Status

The European Union's recent decision to renew the authorization for the use of glyphosate until 15 December 2033 has stimulated scientific discussion all around the world regarding its toxicity or otherwise for humans. Glyphosate is a chemical of which millions of tons have been used in the last 50 years worldwide to dry out weeds in cultivated fields and greenhouses and on roadsides. Concern has been raised in many areas about its possible presence in the food chain and its consequent adverse effects on health. Both aspects that argue in favor of toxicity and those that instead may indicate limited toxicity of glyphosate are discussed here. The widespread debate that has been generated requires further investigations and field measurements to understand glyphosate's fate once dispersed in the environment and its concentration in the food chain. Hence, there is a need for validated analytical methods that are available to analysts in the field. In the present review, methods for the analytical determination of glyphosate and its main metabolite, AMPA, are discussed, with a specific focus on chromatographic techniques applied to cereal products. The experimental procedures are explained in detail, including the cleanup, derivatization, and instrumental conditions, to give the laboratories involved enough information to proceed with the implementation of this line of analysis. The prevalent chromatographic methods used are LC-MS/MS, GC-MS/SIM, and GC-MS/MS, but sufficient indications are also given to those laboratories that wish to use the better performing high-resolution MS or the simpler HPLC-FLD, HPLC-UV, GC-NPD, and GC-FPD techniques for screening purposes. The concentrations of glyphosate from the literature measured in wheat, corn, barley, rye, oats, soybean, and cereal-based foods are reported, together with its regulatory status in various parts of the world and its accumulation mechanism. As for its accumulation in cereals, the available data show that glyphosate tends to accumulate more in wholemeal flours than in refined ones, that its concentration in the product strictly depends on the treatment period (the closer it is to the time of harvesting, the higher the concentration), and that in cold climates, the herbicide tends to persist in the soil for a long time.

Defense and senescence interplay in legume nodules

Immunity and senescence play a crucial role in the functioning of the legume symbiotic nodules. The miss-regulation of one of these processes compromises the symbiosis leading to death of the endosymbiont and the arrest of the nodule functioning. The relationship between immunity and senescence has been extensively studied in plant organs where a synergistic response can be observed. However, the interplay between immunity and senescence in the symbiotic organ is poorly discussed in the literature and these phenomena are often mixed up. Recent studies revealed that the cooperation between immunity and senescence is not always observed in the nodule, suggesting complex interactions between these two processes within the symbiotic organ. Here, we discuss recent results on the interplay between immunity and senescence in the nodule and the specificities of this relationship during legume-rhizobium symbiosis.

A review of organophosphonates, their natural and anthropogenic sources, environmental fate and impact on microbial greenhouse gases emissions - Identifying knowledge gaps

Organophosphonates (OPs) are a unique group of natural and synthetic compounds, characterised by the presence of a stable, hard-to-cleave bond between the carbon and phosphorus atoms. OPs exhibit high resistance to abiotic degradation, excellent chelating properties and high biological activity. Despite the huge and increasing scale of OP production and use worldwide, little is known about their transportation and fate in the environment. Available data are dominated by information concerning the most recognised organophosphonate - the herbicide glyphosate - while other OPs have received little attention. In this paper, a comprehensive review of the current state of knowledge about natural and artificial OPs is presented (including glyphosate). Based on the available literature, a number of knowledge gaps have been identified that need to be filled in order to understand the environmental effects of these abundant compounds. Special attention has been given to GHG-related processes, with a particular focus on CH4. This stems from the recent discovery of OP-dependent CH4 production in aqueous environments under aerobic conditions. The process has changed the perception of the biogeochemical cycle of CH4, since it was previously thought that biological methane formation was only possible under anaerobic conditions. However, there is a lack of knowledge on whether OP-associated methane is also formed in soils. Moreover, it remains unclear whether anthropogenic OPs affect the CH4 cycle, a concern of significant importance in the context of the increasing rate of global warming. The literature examined in this review also calls for additional research into the date of OPs in waste and sewage and in their impact on environmental microbiomes.

Preliminary data on glyphosate, glufosinate, and metabolite contamination in Italian honey samples

Glyphosate and glufosinate are among the most widely used pesticides in agriculture worldwide. Their extensive use leads to the presence of their residues on crops and in the surrounding environment. Beehives, bees, and apiculture products can represent potential sources for the accumulation of these substances and their metabolites, and the consequences for bee health, as well as the level of risk to human health from consuming contaminated food, are still unclear. Furthermore, information on the contamination levels of honey and other beehive products by these compounds remains poorly documented. This study is part of a broader research effort aimed at developing specific analytical methods for monitoring the level of these contaminants in bee products. The methodology employed enabled the acquisition of preliminary information concerning the levels of glyphosate and glufosinate contamination in honey samples obtained from various retailers in Italy to assess compliance with the limits established by Regulation 293/2013. The liquid chromatography tandem mass spectrometry analysis of the 30 honey samples revealed quantifiable levels of glyphosate in eight samples, with contamination ranging from 5.4 to 138.5 ng/g. Notably, one sample of the wild-flower type showed residue levels nearly three times the maximum residue limit. Additionally, trace levels of glyphosate contamination were detected in another ten samples. It is noteworthy that glufosinate and its metabolites were not detected in any of the analyzed samples within the established method's detection ranges.

Identification of a novel thermostable transaminase and its application in L-phosphinothricin biosynthesis

Transaminase (TA) is a crucial biocatalyst for enantioselective production of the herbicide L-phosphinothricin (L-PPT). The use of enzymatic cascades has been shown to effectively overcome the unfavorable thermodynamic equilibrium of TA-catalyzed transamination reaction, also increasing demand for TA stability. In this work, a novel thermostable transaminase (PtTA) from Pseudomonas thermotolerans was mined and characterized. The PtTA showed a high specific activity (28.63 U/mg) towards 2-oxo-4-[(hydroxy)(methyl)phosphinoyl]butyric acid (PPO), with excellent thermostability and substrate tolerance. Two cascade systems driven by PtTA were developed for L-PPT biosynthesis, including asymmetric synthesis of L-PPT from PPO and deracemization of D, L-PPT. For the asymmetric synthesis of L-PPT from PPO, a three-enzyme cascade was constructed as a recombinant Escherichia coli (E. coli G), by co-expressing PtTA, glutamate dehydrogenase (GluDH) and D-glucose dehydrogenase (GDH). Complete conversion of 400 mM PPO was achieved using only 40 mM amino donor L-glutamate. Furthermore, by coupling D-amino acid aminotransferase (Ym DAAT) from Bacillus sp. YM-1 and PtTA, a two-transaminase cascade was developed for the one-pot deracemization of D, L-PPT. Under the highest reported substrate concentration (800 mM D, L-PPT), a 90.43% L-PPT yield was realized. The superior catalytic performance of the PtTA-driven cascade demonstrated that the thermodynamic limitation was overcome, highlighting its application prospect for L-PPT biosynthesis. KEY POINTS: • A novel thermostable transaminase was mined for L-phosphinothricin biosynthesis. • The asymmetric synthesis of L-phosphinothricin was achieved via a three-enzyme cascade. • Development of a two-transaminase cascade for D, L-phosphinothricin deracemization.

Trimethylation Enhancement Using Diazomethane (TrEnDi) Enables Enhanced Detection of Glufosinate and 3-(Methylphosphinico)propionic Acid from Complex Canola Samples

Over the past century, agriculture practices have transitioned from manual cultivation to the use of an array of chemical herbicides for weed control including phosphinothricin, or glufosinate (GLUF). Consequently, the potential for long-term residual GLUF exposure in the food chain has increased, highlighting the need for improved analytical strategies for its detection, as well as the detection of its main breakdown product 3-(methylphosphinico)propionic acid (MPPA). Chemical derivatization strategies have been developed to improve the detection of GLUF and MPPA via liquid chromatography tandem mass spectrometry analyses. Herein, we employ trimethylation enhancement using diazomethane (TrEnDi) for the first time as a means to confer analytical advantages via quantitatively derivatizing these analytes into permethylated GLUF ([GLUFTr]+) and MPPA ([MPPATr+H]+). Comparing [GLUFTr]+ and [MPPATr+H]+ to underivatized counterparts, TrEnDi yields 2.8-fold and 1.7-fold improvements in reversed-phase chromatographic retention, respectively, while MS-based sensitivity is enhanced 4.1-fold and 11.0-fold, respectively. Successful analyte derivatization (with >99% yields) was further demonstrated on a commercial herbicide solution imparting consistent analytical enhancements. To investigate the benefits of TrEnDi in a bona fide agricultural scenario, simple aqueous extractions from distinct parts of field-grown canola plants were performed to quantify GLUF and MPPA before and after TrEnDi derivatization. In their underivatized forms, GLUF and MPPA were undetectable in all field samples, whereas [GLUFTr]+ and [MPPATr+H]+ were readily quantifiable using the same analysis conditions. Our results demonstrate that TrEnDi continues to be a useful tool to enhance the analytical characteristics of organic molecules that are traditionally difficult to detect.

Nano-Agrochemicals as Substitutes for Pesticides: Prospects and Risks

This review delves into the mesmerizing technology of nano-agrochemicals, specifically pesticides and herbicides, and their potential to aid in the achievement of UN SDG 17, which aims to reduce hunger and poverty globally. The global market for conventional pesticides and herbicides is expected to reach USD 82.9 billion by 2027, growing 2.7% annually, with North America, Europe, and the Asia-Pacific region being the biggest markets. However, the extensive use of chemical pesticides has proven adverse effects on human health as well as the ecosystem. Therefore, the efficacy, mechanisms, and environmental impacts of conventional pesticides require sustainable alternatives for effective pest management. Undoubtedly, nano-agrochemicals have the potential to completely transform agriculture by increasing crop yields with reduced environmental contamination. The present review discusses the effectiveness and environmental impact of nanopesticides as promising strategies for sustainable agriculture. It provides a concise overview of green nano-agrochemical synthesis and agricultural applications, and the efficacy of nano-agrochemicals against pests including insects and weeds. Nano-agrochemical pesticides are investigated due to their unique size and exceptional performance advantages over conventional ones. Here, we have focused on the environmental risks and current state of nano-agrochemicals, emphasizing the need for further investigations. The review also draws the attention of agriculturists and stakeholders to the current trends of nanomaterial use in agriculture especially for reducing plant diseases and pests. A discussion of the pros and cons of nano-agrochemicals is paramount for their application in sustainable agriculture.

Molecular Targets of Herbicides and Fungicides─Are There Useful Overlaps for Fungicide Discovery?

New fungicide modes of action are needed for fungicide resistance management strategies. Several commercial herbicide targets found in fungi that are not utilized by commercial fungicides are discussed as possible fungicide molecular targets. These are acetyl CoA carboxylase, acetolactate synthase, 5-enolpyruvylshikimate-3-phosphate synthase, glutamine synthase, phytoene desaturase, protoporphyrinogen oxidase, long-chain fatty acid synthase, dihydropteroate synthase, hydroxyphenyl pyruvate dioxygenase, and Ser/Thr protein phosphatase. Some of the inhibitors of these herbicide targets appear to be either good fungicides or good leads for new fungicides. For example, some acetolactate synthase and dihydropteroate inhibitors are excellent fungicides. There is evidence that some herbicides have indirect benefits to certain crops due to their effects on fungal crop pathogens. Using a pesticide with both herbicide and fungicide activities based on the same molecular target could reduce the total amount of pesticide used. The limitations of such a product are discussed.

Developmental synapse pathology triggered by maternal exposure to the herbicide glufosinate ammonium

Environmental and genetic factors influence synapse formation. Numerous animal experiments have revealed that pesticides, including herbicides, can disturb normal intracellular signals, gene expression, and individual animal behaviors. However, the mechanism underlying the adverse outcomes of pesticide exposure remains elusive. Herein, we investigated the effect of maternal exposure to the herbicide glufosinate ammonium (GLA) on offspring neuronal synapse formation in vitro. Cultured cerebral cortical neurons prepared from mouse embryos with maternal GLA exposure demonstrated impaired synapse formation induced by synaptic organizer neuroligin 1 (NLGN1)-coated beads. Conversely, the direct administration of GLA to the neuronal cultures exhibited negligible effect on the NLGN1-induced synapse formation. The comparison of the transcriptomes of cultured neurons from embryos treated with maternal GLA or vehicle and a subsequent bioinformatics analysis of differentially expressed genes (DEGs) identified "nervous system development," including "synapse," as the top-ranking process for downregulated DEGs in the GLA group. In addition, we detected lower densities of parvalbumin (Pvalb)-positive neurons at the postnatal developmental stage in the medial prefrontal cortex (mPFC) of offspring born to GLA-exposed dams. These results suggest that maternal GLA exposure induces synapse pathology, with alterations in the expression of genes that regulate synaptic development via an indirect pathway distinct from the effect of direct GLA action on neurons.

Sub-acute toxicity of the herbicide glufosinate-ammonium exposure in adult red swamp crayfish (Procambarus clarkii)

Glufosinateammonium (GLA) is one of the most widely used agricultural herbicides. It is frequently detected in surface waters near farmland and may pose a risk to non-target aquatic species. This study aimed to explore the toxicity of subacute GLA exposure in crayfish. Adult red swamp crayfish were exposed to GLA (0, 1, 10, and 100 mg/L) for 21 days. Bioaccumulation, oxidative stress, nonspecific immunity, and the expression of genes encoding xenobiotic detoxification-related enzymes were examined. The results showed GLA accumulation and hepatopancreatic histopathological changes (dilation of hepatic tubules and vacuolation of hepatocytes) in the exposed crayfish. GLA exposure induced ROS production, inhibited glutathione expression, and catalase activity in the crayfish hepatopancreas, as well as inhibited immunoenzyme expression (acid phosphatase, alkaline phosphatase, and lysozyme) in the hemolymph. In addition, the total hemocyte number decreased, and the proportion of hemocyte subsets changed significantly. Superoxide dismutase first increased and then decreased with increasing GLA dosage. GLA promoted the expression of biotransformation enzymes (cypb5, gst) in the hepatopancreas. Our results suggest that subacute GLA exposure caused structural damage to the hepatopancreatic tissue and decreased antioxidant capacity and non-specific immunity in crayfish. These findings provide insight into the toxicity of herbicides on non-target organisms.

Heterologous expression of a deacetylase and its application in L-glufosinate preparation

With potent herbicidal activity, biocatalysis synthesis of L-glufosinate has drawn attention. In present research, NAP-Das2.3, a deacetylase capable of stereoselectively resolving N-acetyl-L-glufosinate to L-glufosinate mined from Arenimonas malthae, was heterologously expressed and characterized. In Escherichia coli, NAP-Das2.3 activity only reached 0.25 U/L due to the formation of inclusive bodies. Efficient soluble expression of NAP-Das2.3 was achieved in Pichia pastoris. In shake flask and 5 L bioreactor fermentation, NAP-Das2.3 activity by recombinant P. pastoris reached 107.39 U/L and 1287.52 U/L, respectively. The optimum temperature and pH for N-acetyl-glufosinate hydrolysis by NAP-Das2.3 were 45 °C and pH 8.0, respectively. The Km and Vmax of NAP-Das2.3 towards N-acetyl-glufosinate were 25.32 mM and 19.23 μmol mg-1 min-1, respectively. Within 90 min, 92.71% of L-enantiomer in 100 mM racemic N-acetyl-glufosinate was converted by NAP-Das2.3. L-glufosinate with high optical purity (e.e.P above 99.9%) was obtained. Therefore, the recombinant NAP-Das2.3 might be an alternative for L-glufosinate biosynthesis.

Eleusine indica Cytochrome P450 and Glutathione S-Transferase Are Linked to High-Level Resistance to Glufosinate

Eleusine indica has become a global nuisance weed and has evolved resistance to glufosinate. The involvement of target-site resistance (TSR) in glufosinate resistance in E. indica has been elucidated, while the role of nontarget-site resistance (NTSR) remains unclear. Here, we identified a glufosinate-resistant (R) population that is highly resistant to glufosinate, with a resistance index of 13.5-fold. Molecular analysis indicated that the resistance mechanism of this R population does not involve TSR. In addition, pretreatment with two known metabolic enzyme inhibitors, the cytochrome P450 (CYP450) inhibitor malathion and the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl), increased the sensitivity of the R population to glufosinate. The results of subsequent RNA sequencing (RNA-seq) and quantitative real-time PCR (RT-qPCR) suggested that the constitutive overexpression of a GST gene (GSTU3) and three CYP450 genes (CYP94s and CYP71) may play an important role in glufosinate resistance. This study provides new insights into the resistance mechanism of E. indica.

Development of an aminotransferase-driven biocatalytic cascade for deracemization of d,l-phosphinothricin

2-oxo-4-[(hydroxy)(methyl)phosphinoyl]butyric acid (PPO) is the essential precursor keto acid for the asymmetric biosynthesis of herbicide l-phosphinothricin (l-PPT). Developing a biocatalytic cascade for PPO production with high efficiency and low cost is highly desired. Herein, a d-amino acid aminotransferase from Bacillus sp. YM-1 (Ym DAAT) with high activity (48.95 U/mg) and affinity (Km  = 27.49 mM) toward d-PPT was evaluated. To circumvent the inhibition of by-product d-glutamate (d-Glu), an amino acceptor (α-ketoglutarate) regeneration cascade was constructed as a recombinant Escherichia coli (E. coli D), by coupling Ym d-AAT, d-aspartate oxidase from Thermomyces dupontii (TdDDO) and catalase from Geobacillus sp. CHB1. Moreover, the regulation of the ribosome binding site was employed to overcome the limiting step of expression toxic protein TdDDO in E. coli BL21(DE3). The aminotransferase-driven whole-cell biocatalytic cascade (E. coli D) showed superior catalytic efficiency for the synthesis of PPO from d,l-phosphinothricin (d,l-PPT). It revealed the production of PPO exhibited high space-time yield (2.59 g L-1  h-1 ) with complete conversion of d-PPT to PPO at high substrate concentration (600 mM d,l-PPT) in 1.5 L reaction system. This study first provides the synthesis of PPO from d,l-PPT employing an aminotransferase-driven biocatalytic cascade.

Identification and Expression Analysis of EPSPS and BAR Families in Cotton

Weeds seriously affect the yield and quality of crops. Because manual weeding is time-consuming and laborious, the use of herbicides becomes an effective way to solve the harm caused by weeds in fields. Both 5-enolpyruvyl shikimate-3-phosphate synthetase (EPSPS) and acetyltransferase genes (bialaphos resistance, BAR) are widely used to improve crop resistance to herbicides. However, cotton, as the most important natural fiber crop, is not tolerant to herbicides in China, and the EPSPS and BAR family genes have not yet been characterized in cotton. Therefore, we explore the genes of these two families to provide candidate genes for the study of herbicide resistance mechanisms. In this study, 8, 8, 4, and 5 EPSPS genes and 6, 6, 5, and 5 BAR genes were identified in allotetraploid Gossypium hirsutum and Gossypium barbadense, diploid Gossypium arboreum and Gossypium raimondii, respectively. Members of the EPSPS and BAR families were classified into three subgroups based on the distribution of phylogenetic trees, conserved motifs, and gene structures. In addition, the promoter sequences of EPSPS and BAR family members included growth and development, stress, and hormone-related cis-elements. Based on the expression analysis, the family members showed tissue-specific expression and differed significantly in response to abiotic stresses. Finally, qRT-PCR analysis revealed that the expression levels of GhEPSPS3, GhEPSPS4, and GhBAR1 were significantly upregulated after exogenous spraying of herbicides. Overall, we characterized the EPSPS and BAR gene families of cotton at the genome-wide level, which will provide a basis for further studying the functions of EPSPS and BAR genes during growth and development and herbicide stress.

Effects of Biological Nitrogen Metabolism on Glufosinate-Susceptible and -Resistant Goosegrass (Eleusine indica L.)

Glufosinate is a broad-spectrum herbicide used to control most weeds in agriculture worldwide. Goosegrass (Eleusine indica L.) is one of the top ten malignant weeds across the world, showing high tolerance to glufosinate via different mechanisms that are not yet fully understood. This study revealed that nitrogen metabolism could be a target-resistant site, providing clues to finally clarify the mechanism of glufosinate resistance in resistant goosegrass populations. Compared to susceptible goosegrass (NX), the resistant goosegrass (AUS and CS) regarding the stress of glufosinate showed stronger resistance with lower ammonia contents, higher target enzyme GS (glutamine synthetase) activity, and lower GOGAT (glutamine 2-oxoglutarate aminotransferase) activity. The GDH (glutamate dehydrogenase) activity of another pathway increased, but its gene expression was downregulated in resistant goosegrass (AUS). Analyzing the transcriptome and proteome data of goosegrass under glufosinate stress at 36 h showed that the KEGG pathway of the nitrogen metabolism was enriched in glufosinate-susceptible goosegrass (NX), but not in glufosinate-resistant goosegrass (CS and AUS). Several putative target genes involved in glufosinate stress countermeasures were identified. This study provides specific insights into the nitrogen metabolism of resistant goosegrass, and gives a basis for future functional verification of glufosinate-tolerance genes in plants.

Visible light irradiated photocatalytic C(sp3)-H phosphorylation of xanthenes and 9,10-dihydroacridines with P(O)-H compounds

Photocatalytic C(sp3)-H phosphorylation of xanthenes and 9,10-dihydroacridines with P(O)-H compounds under the irradiation of 18 W blue LEDs at room temperature using fluorescein as the photocatalyst and molecular oxygen (O2) as the sole oxidant has been achieved. The newly developed reaction provides direct access to 9-phosphorylated xanthene derivatives with good functional group compatibility.

Deep Learning-Based Automatic Duckweed Counting Using StarDist and Its Application on Measuring Growth Inhibition Potential of Rare Earth Elements as Contaminants of Emerging Concerns

In recent years, there have been efforts to utilize surface water as a power source, material, and food. However, these efforts are impeded due to the vast amounts of contaminants and emerging contaminants introduced by anthropogenic activities. Herbicides such as Glyphosate and Glufosinate are commonly known to contaminate surface water through agricultural industries. In contrast, some emerging contaminants, such as rare earth elements, have started to enter the surface water from the production and waste of electronic products. Duckweeds are angiosperms from the Lemnaceae family and have been used for toxicity tests in aquatic environments, mainly those from the genus Lemna, and have been approved by OECD. In this study, we used duckweed from the genus Wolffia, which is smaller and considered a good indicator of metal pollutants in the aquatic environment. The growth rate of duckweed is the most common endpoint in observing pollutant toxicity. In order to observe and mark the fronds automatically, we used StarDist, a machine learning-based tool. StarDist is available as a plugin in ImageJ, simplifying and assisting the counting process. Python also helps arrange, manage, and calculate the inhibition percentage after duckweeds are exposed to contaminants. The toxicity test results showed Dysprosium to be the most toxic, with an IC50 value of 14.6 ppm, and Samarium as the least toxic, with an IC50 value of 279.4 ppm. In summary, we can provide a workflow for automatic frond counting using StarDist integrated with ImageJ and Python to simplify the detection, counting, data management, and calculation process.

Sensing of organophosphorus pesticides by fluorescent complexes based on purine-hydrazone receptor and copper (II) and its application in living-cells imaging

In this study, we used purine hydrazone derivatives and coumarin aldehyde to synthesize a novel fluorescent sensor (EDTP) by Schiff base reaction, which exhibited significant selective fluorescence quenching of Cu²⁺, and a distinct change from brilliant yellow to red is present along with the solution color. The detection limit of EDTP for Cu²⁺ was 109.52 nM. Job's plot experiment, density flooding theory (DFT) and ¹H NMR titration experiments revealed the possible binding mechanism of EDTP to Cu²⁺, the probe EDTP could achieve highly detection of Cu²⁺ through forming a 1:1 complex. Additionally, this new fluorescent sensor EDTP-Cu²⁺ can be further applied in the rapid and selective detection of pesticide residues in solutions. When the EDTP-Cu²⁺ system was subsequently exposed to organophosphorus pesticides (glyphosate and glufosinate-ammonium), it was observed that the fluorescence was recovered and accompanied by a red to yellow color change. This may be attributed to the strong chelation of glyphosate and glufosinate-ammonium with Cu²⁺, leading to the dissociation of the EDTP-Cu²⁺ system and thus triggering the fluorescence recovery effect. The detection limits of the EDTP-Cu²⁺ system is 2.48 nM for glyphosate and 17.23 nM for glufosinate-ammonium, respectively. Finally, the developed sensor system has been successfully utilized image glyphosate and glufosinate-ammonium fluorescence in living cells. Purine fluorescence probes are a potential fluorescent probe for the detection of metal ions and pesticides due to their good characteristics. This study opens up a new way for the detection of fluorescent probes in pesticides.

Evaluation of the cytotoxicity and genotoxicity of glufosinate-ammonium at technical and commercial grades in HepG2 cells

Exposure to genotoxic agents is associated with the development of cancer and related diseases. For this reason, assessing the genotoxicity of chemical compounds is necessary. In this line, information about the genotoxic effect of glufosinate-ammonium (GLA) has been reported only for the technical grade. However, humans are frequently exposed to commercial formulations of pesticides. Commercial formulations are characterized by using inner agents that increase toxicity compared to pesticides in technical grade. This study aimed to determine the cytotoxic and genotoxic effects of GLA on HepG2 cells. MTT and comet assays were performed to evaluate cell viability and DNA damage, respectively. HepG2 cells were exposed for 24 h to different concentrations of GLA (at 0.01 µg/mL; 0.04 µg/mL; 0.1 µg/mL; 0.24 µg/mL; 0.52 µg/mL; 1.25 µg/mL; 2.62 µg/mL and 13.12 µg/mL) in commercial- (Finale Ultra®) or technical-grade (GLAT). The results indicated that only Finale Ultra® induced a reduction in cell viability at 13.12 µg/mL. Furthermore, exposure to Finale Ultra® or GLAT was associated with increased DNA damage at concentrations from 0.52-13.12- µg/mL. This study shows the genotoxic effect of GLA on HepG2 cells.

Discovery of Antimicrobial Phosphonopeptide Natural Products from Bacillus velezensis by Genome Mining

Phosphonate natural products are renowned for inhibitory activities which underly their development as antibiotics and pesticides. Although most phosphonate natural products have been isolated from Streptomyces, bioinformatic surveys suggest that many other bacterial genera are replete with similar biosynthetic potential. While mining actinobacterial genomes, we encountered a contaminated Mycobacteroides data set which included a biosynthetic gene cluster predicted to produce novel phosphonate compounds. Sequence deconvolution revealed that the contig containing this cluster, as well as many others, belonged to a contaminating Bacillus and is broadly conserved among multiple species, including the epiphyte Bacillus velezensis. Isolation and structure elucidation revealed a new di- and tripeptide composed of l-alanine and a C-terminal l-phosphonoalanine which we name phosphonoalamides E and F. These compounds exhibit broad-spectrum antibacterial activity, including strong inhibition against the agricultural pests responsible for vegetable soft rot (Erwinia rhapontici), onion rot (Pantoea ananatis), and American foulbrood (Paenibacillus larvae). This work expands our knowledge of phosphonate metabolism and underscores the importance of including underexplored microbial taxa in natural product discovery. IMPORTANCE Phosphonate natural products produced by bacteria have been a rich source of clinical antibiotics and commercial pesticides. Here, we describe the discovery of two new phosphonopeptides produced by B. velezensis with antibacterial activity against human and plant pathogens, including those responsible for widespread soft rot in crops and American foulbrood. Our results provide new insight on the natural chemical diversity of phosphonates and suggest that these compounds could be developed as effective antibiotics for use in medicine or agriculture.

Identification and characterization of a phosphinothricin N-acetyltransferase from Enterobacter LSJC7

Phosphinothricin (PPT) is a widely used and non-selective herbicide. PPT-resistance genes, especially PPT N-acetyltransferase genes, have been used in the development of transgenic PPT-resistant crops. However, there are only a limited number of available PPT-resistance genes for use in plant biotechnology. In this study, we found that Enterobacter LSJC7 is highly resistant to PPT and can acetylate PPT to N-acetyl phosphinothricin (Ac-PPT). Furthermore, a novel PPT N-acetyltransferase gene, named LsarsN, was identified from LSJC7. When LsarsN was expressed in E. coli AW3110, it confered resistance to PPT. Ac-PPT was detected in both the culture medium and cells of AW3110 expressing the LsarsN-pET22b plasmid. The purified LsArsN protein also showed strong N-acetylation ability in vitro, and its enzymatic kinetic curve was fitted with the Michaelis-Mentan equation. Compared with wild-type LsArsN, both R72A and R74A mutants showed significantly lower PPT N-acetylation ability. In summary, our results systematically characterized LsArsN with strong ability for PPT N-acetylation, which lays the groundwork for future research into the use of this novel gene, LsarsN, to create PPT-resistant crops.

Monitoring weed mechanical and chemical damage stress based on chlorophyll fluorescence imaging

Currently, mechanical and chemical damage is the main way to carry out weed control. The use of chlorophyll fluorescence (CF) technology to nondestructively monitor the stress physiological state of weeds is significant to reveal the damage mechanism of mechanical and chemical stresses as well as complex stresses. Under simulated real field environmental conditions, different species and leaf age weeds (Digitaria sanguinalis 2-5 leaf age, and Erigeron canadensis 5-10 leaf age) were subjected to experimental treatments for 1-7 days, and fluorescence parameters were measured every 24 h using a chlorophyll fluorometer. The aim of this study was to investigate the changes in CF parameters of different species of weeds (Digitaria sanguinalis, Erigeron canadensis) at their different stress sites under chemical, mechanical and their combined stresses. The results showed that when weeds (Digitaria sanguinalis and Erigeron canadensis) were chemically stressed in different parts, their leaf back parts were the most severely stressed after 7 days, with photosynthetic inhibition reaching R=75%. In contrast, mechanical stress differs from its changes, and after a period of its stress, each parameter recovers somewhat after 1 to 2 days of stress, with heavy mechanical stress R=11%. Complex stress had the most significant effect on CF parameters, mainly in the timing and efficiency of changes in Fv/Fm, Fq'/Fm', ETR, Rfd, NPQ and Y(NO), with R reaching 71%-73% after only 3-4 days of complex stress, and its changes in complex stress were basically consistent with the pattern of changes in its chemical stress. The results of the study will help to understand the effects of mechanical and chemical stresses and combined stresses on CF parameters of weeds and serve as a guide for efficient weed control operations and conducting weed control in the future.

Soil management affects carbon and nitrogen concentrations and stable isotope ratios in vine products

Weeds reduce vineyard productivity and affect grape quality by competing with grapevines (Vitis vinifera L.) for water and nutrients. The increased banning of herbicides has prompted the evaluation of alternative soil management strategies. Cover cropping seems to be the best alternative for weed management. However, it may impact vine growth, grape yield, and quality. Quantitative studies on these changes are scarce. Our study aimed to investigate the combined effect of grass cover and water availability on vines of three cultivars, the white Chasselas and Petite Arvine and the red Pinot noir field-grown under identical climatic and pedological conditions and grafted onto the same rootstock. Soil management and irrigation experiments were performed during the 2020-2021 seasons. Two extreme soil management practices were established in the vineyard, based on 100 % bare soil (BS) by the application of herbicides with glufosinate or glyphosate as active ingredients and 100 % grass-covered soil (GS) by cover cropping with a mixture of plant species. Two water statuses were imposed by drip irrigation (DI) and no irrigation (NI). The level of vine-weed competition for water and nitrogen (N) was assessed in the vine, must, and wine solid residues (WSRs) by comparing measurements, i.e., the yeast assimilable N content, C/N_WSR, carbon and N isotope ratios (δ¹³C_grape-sugars, δ¹³C_WSR, and δ¹⁵N_WSR) among the different treatments (BS-DI, BS-NI, GS-DI, GS-NI). The increase in the δ¹³C_grape-sugars and δ¹³C_WSR values with increasing plant water deficit mimicked the observations in irrigation experiments on BS. The N_WSR content and δ¹⁵N_WSR values decreased with water stress and much more strongly in vines on GS. The dramatic N deficit in rainfed vines on GS could be alleviated with irrigation. The present study provides insights from chemical and stable isotope analyses into the potential impact of cover cropping in vineyards in the context of the banning of herbicides in a time of global water scarcity due to climate change.

The Arabidopsis Target of Rapamycin (TOR) kinase regulates ammonium assimilation and glutamine metabolism

In eukaryotes, Target of Rapamycin (TOR) is a well conserved kinase that controls cell metabolism and growth in response to nutrients and environmental factors. Nitrogen (N) is an essential element for plants, and TOR functions as a crucial N and amino acid sensor in animals and yeast. However, knowledge on the connections between TOR and the overall N metabolism and assimilation in plants is still limited. In this study, we investigated the regulation of TOR in Arabidopsis (Arabidopsis thaliana) by the N source as well as the impact of TOR deficiency on N metabolism. Inhibition of TOR globally decreased ammonium uptake while triggering a massive accumulation of amino acids, such as Gln, but also of polyamines. Consistently, TOR complex mutants were hypersensitive to Gln. We also showed that the glutamine synthetase inhibitor glufosinate abolishes Gln accumulation resulting from TOR inhibition and improves the growth of TOR complex mutants. These results suggest that a high level of Gln contributes to the reduction in plant growth resulting from TOR inhibition. Glutamine synthetase activity was reduced by TOR inhibition while the enzyme amount increased. In conclusion, our findings show that the TOR pathway is intimately connected to N metabolism and that a decrease in TOR activity results in glutamine synthetase-dependent Gln and amino acid accumulation.

Insights into the effects of sublethal doses of pesticides glufosinate-ammonium and sulfoxaflor on honey bee health

Insect pollinators are threatened worldwide, being the exposure to multiple pesticides one of the most important stressor. The herbicide Glyphosate and the insecticide Imidacloprid are among the most used pesticides worldwide, although different studies evidenced their detrimental effects on non-target organisms. The emergence of glyphosate-resistant weeds and the recent ban of imidacloprid in Europe due to safety concerns, has prompted their replacement by new molecules, such as glufosinate-ammonium (GA) and sulfoxaflor (S). GA is a broad-spectrum and non-selective herbicide that inhibits a key enzyme in the metabolism of nitrogen, causing accumulation of lethal levels of ammonia; while sulfoxaflor is an agonist at insect nicotinic acetylcholine receptors (nAChRs) and generates excitatory responses including tremors, paralysis and mortality. Although those molecules are being increasingly used for crop protection, little is known about their effects on non-target organisms. In this study we assessed the impact of chronic and acute exposure to sublethal doses of GA and S on honey bee gut microbiota, immunity and survival. We found GA significantly reduced the number of gut bacteria, and decreased the expression of glucose oxidase, a marker of social immunity. On the other hand, S significantly increased the number of gut bacteria altering the microbiota composition, decreased the expression of lysozyme and increased the expression of hymenoptaecin. These alterations in gut microbiota and immunocompetence may lead to an increased susceptibility to pathogens. Finally, both pesticides shortened honey bee survival and increased the risk of death. Those results evidence the negative impact of GA and S on honey bees, even at single exposition to a low dose, and provide useful information to the understanding of pollinators decline.

Molecular targets of insecticides and herbicides - Are there useful overlaps?

New insecticide modes of action are needed for insecticide resistance management strategies. The number of molecular targets of commercial herbicides and insecticides are fewer than 35 for both. Few commercial insecticide targets are found in plants, but ten targets of commercial herbicides are found in insects. For several of these commonly held targets, some compounds kill both plants and insects. For example, herbicidal inhibitors of p-hydroxyphenylpyruvate dioxygenase are effective insecticides on blood-fed insects. The glutamine synthetase-inhibiting herbicide glufosinate is insecticidal by the same mechanism of action, inhibition of glutamine synthetase. These and other examples of shared activities of commercial herbicides with insecticides through the same target site are discussed. Compounds with novel herbicide targets shared by insects that are not commercialized as pesticides (such as statins) are also discussed. Compounds that are both herbicidal and insecticidal can be used for insect pests not associated with crops or with crops made resistant to the compounds.

Glyphosate and Glufosinate Residues in Honey and Other Hive Products

Hive products have numerous beneficial properties; however, the hive’s health is affected by the surrounding environment. The widespread use of herbicides in agriculture, such as glyphosate and glufosinate, has raised alarm among consumers, beekeepers, and environmentalists due to their potential to harm bees and humans through the consumption of bee products. This review aims to provide a comprehensive overview of the presence of glyphosate, glufosinate, and their metabolites in hive products, collecting and comparing available data from peer-reviewed research and surveys conducted across several countries. Moreover, it analyzes and discusses the potential impacts of these substances on human and bee health, analytical aspects, and recent regulatory developments. The data has revealed that these substances can be present in the different matrices tested, but the concentrations found are usually lower than the maximum residue limits set. However, the use of different methodologies with non-uniform analytical performances, together with an incomplete search for regulated analytes, leads to heterogeneity and makes comparisons challenging. In addition to the completion of studies on the toxicology of herbicide active ingredients, further monitoring actions are necessary, harmonizing analytical methodologies and data management procedures.

Sulfadiazine and phosphinothricin selection systems optimised for the transformation of tobacco BY-2 cells

We extended the applicability of the BY-2 cell line as a model by introducing two new selection systems. Our protocol provides guidelines for optimising Basta selection in other recalcitrant models. Tobacco BY-2 cell line is the most commonly used cytological model in plant research. It is uniform, can be simply treated by chemicals, synchronised and easily transformed. However, only a few selection systems are available that complicate advanced studies using multiple stacked transgenes and extensive gene editing. In our work, we adopted for BY-2 cell line two other selection systems: sulfadiazine and phosphinothricin (PPT, an active ingredient of Basta herbicide). We show that sulfadiazine can be used in a wide range of concentrations. It is suitable for co-transformation and subsequent double selection with kanamycin or hygromycin, which are standardly used for BY-2 transformation. We also have domesticated the sulfadiazine resistance for the user-friendly GoldenBraid cloning system. Compared to sulfadiazine, establishing selection on phosphinothricin was considerably more challenging. It did not work in any concentration of PPT with standardly cultured cells. Since the selection is based on blocking glutamine synthetase and consequent ammonium toxicity and deficiency of assimilated nitrogen, we tried to manipulate nitrogen availability. We found that the PPT selection reliably works only with nitrogen-starved cells with reduced nitrate reserves that are selected on a medium without ammonium nitrate. Both these adjustments prevent the release of large amounts of ammonium, which can toxify the entire culture in the case of standardly cultured cells. Since high nitrogen reserves can be a common feature of in vitro cultures grown on MS media, nitrogen starvation could be a key step in establishing phosphinothricin resistance in other plant models.

The trend of ammonia levels in patients with glufosinate ammonium poisoning with respect to neurotoxicity

Since glufosinate irreversibly inhibits glutamine synthetase, leading to intracellular accumulation of ammonia, hyperammonemia is considered one of the main mechanisms of glufosinate ammonium toxicity in humans. However, whether hyperammonemia causes neurotoxicity has not yet been studied. Therefore, the purpose of this study was to determine whether the serum ammonia level is elevated before the development of neurotoxicity. In this retrospective observational study, we analyzed data from consecutive patients diagnosed with acute glufosinate ammonium poisoning. The primary outcome was the development of neurotoxicity following the poisoning. Patients who developed neurotoxicity were characterized by higher initial ammonia levels compared to patients without neurotoxicity (121.0 µg/dL [87.0; 141.0] vs 83.0 µg/dL [65.0; 119.0], p < 0.01). However, there was no increase in ammonia levels over time in both the asymptomatic and neurotoxicity groups when serial serum ammonia levels were examined from emergency department admission to hospital discharge. In addition, there was no statistically significant difference between the peak ammonia levels in the asymptomatic group and the peak ammonia levels before symptom onset in the neurotoxicity group (135.0 µg/dL [109.0; 158.0] vs 144.0 µg/dL [120.0; 189.0], p = 0.15). Following the onset of neurotoxicity, the serum ammonia level increased significantly (125.0 [111.0; 151.0] µg/dL to 148.0 [118.0; 183.0] µg/dL, p < 0.01). In conclusion, hyperammonemia cannot be assumed as the cause of neurotoxicity in glufosinate ammonium poisoning and further research is needed to examine the exact mechanism of GA poisoning.

Comparison of the chronic and multigenerational toxicity of racemic glufosinate and l-glufosinate to Caenorhabditis elegans at environmental concentrations

Glufosinate-ammonium, the second largest transgene crop resistant herbicide, is classified as a mobile persistent pollutant by the U.S. Environmental Protection Agencybecause of its slow decomposition and easy mobile transfer in a water environment. The chronic and multigeneration toxicity of this compound to environmental organisms are alarming. In this study, racemic glufosinate-ammonium and the effective isomer, l-glufosinate-ammonium, were used as the test agents. The developmental, neurotoxic and reproductive toxicities of Caenorhabditis elegans to their parents and progeny were studied by continuous exposure in water at concentrations of 0.1, 1, 10 and 100 μg/L. The causes of toxicity differences were analysed from oxidative stress and transcription levels. Through oxidative stress of C. elegans, racemic glufosinate-ammonium and l-glufosinate-ammonium both mediated the developmental toxicity (shortened developmental cycle, reduced body length and width, promoted ageingand decreased longevity), neurotoxicity (inhibited head swinging, body bending frequency and acetylcholinesterase [AchE] activity) and reproductive toxicity (significant reductions in the number of eggs and offspring in vivo and induced apoptosis of gonadal cells). These phenomena caused oxidative damage (protein and membrane lipid peroxidation) and further induced apoptosis. The changes in various indicators caused by racemic glufosinate-ammonium exposure were more significant than those caused by l-glufosinate-ammonium exposure, and the reproduction-related indicators were more significant than the developmental and neurological indicators. A continuous accumulation of toxicity was observed after multiple generations of continuous exposure. These research results provide a data reference for the ecotoxicological evaluation and risk assessment of glufosinate-ammonium and contribute to the revision and improvement of the related environmental policies of glufosinate-ammonium.

Urinary concentrations and determinants of glyphosate and glufosinate in pregnant Canadian participants in the MIREC study

BACKGROUND

Glyphosate is the most widely applied herbicide in agriculture. Glufosinate is a broad spectrum herbicide used to manage glyphosate-resistant weeds. Despite the widespread use of these herbicides, biomonitoring data - which inform risk assessment and management - are sparse.

OBJECTIVES

To identify determinants of urinary concentrations of these herbicides and their metabolites in pregnancy.

METHODS

We measured urinary concentrations of glyphosate, glufosinate, and their primary metabolites aminomethylphosphonic acid (AMPA) and 3-methylphosphinicopropionic acid (3-MPPA) in a single spot urine specimen collected during the first trimester of pregnancy from the Maternal-Infant Research on Environmental Chemicals (MIREC) study. MIREC recruited about 2000 pregnant women from 10 Canadian cities between 2008 and 2011. We used UItra-Performance Liquid Chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) with sensitive limits of detection to quantify analyte concentrations. We examined urinary concentrations according to maternal sociodemographics, sample collection characteristics, reported pesticide use, and consumption of fruits, vegetables, legumes, and grain products. We used ANOVA models with specific gravity-standardized chemical concentrations as the dependent variable to determine associations with maternal and sample determinants.

RESULTS

Among women with biobanked urine samples (n = 1829-1854), 74% and 72% had detectable concentrations of glyphosate and AMPA, respectively. In contrast, one and six percent of women had detectable concentrations of glufosinate and 3-MPPA, respectively. The specific gravity-standardized geometric mean (95% CI) concentrations of glyphosate and AMPA were 0.112 (0.099-0.127) μg/L and 0.159 (0.147-0.172) μg/L, respectively. We observed a dose-response relationship between consumption of whole grain bread and higher urinary glyphosate concentrations. Season of urine collection and self-reported pesticide use were not associated with increased concentrations of any analyte.

CONCLUSIONS

We detected glyphosate and AMPA in the majority of pregnant women from this predominantly urban Canadian cohort. Diet was a probable route of exposure.

Improved Method for the Detection of Highly Polar Pesticides and Their Main Metabolites in Foods of Animal Origin: Method Validation and Application to Monitoring Programme

The application of polar pesticides in agricultural production has been of great interest due to their low costs and their high effectiveness. For this reason, the possibility of their transfer to foods of animal origin is of great concern for human health. The manuscript describes the implementation and validation of an analytical method to detect polar pesticides, at regulatory levels, in three foods of animal origin, including bovine fat, chicken eggs, and cow milk. The method was fully validated to detect glyphosate, glufosinate, and their respective metabolites in the above-mentioned foods obtaining fit-for-purpose sensitivity, recoveries (76–119%), repeatability (≤20%), within-laboratory reproducibility (≤20%), and experimental measurement uncertainty less than 50% as required by the SANTE/11312/2021 criteria. Given the satisfactory results, the applicability of the method to additional molecules belonging to the same category (AMPA, cyanuric acid, ethephon, fosetyl aluminum, HEPA, maleic hydrazide, and N-acetyl-glyphosate) was also evaluated in order to meet possible future requests. Finally, the implemented method was applied to analyse samples over the period of March 2021 to August 2022 from two Italian regions (Umbria and Marche) within the national monitoring programme. In agreement with previously available data, none of the samples analysed showed the presence of glyphosate and glufosinate at levels above the legal limit.

Modern Approaches for the Development of New Herbicides Based on Natural Compounds

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective.

Convergent and divergent biosynthetic strategies towards phosphonic acid natural products

The phosphonate class of natural products have received significant interests in the post-genomic era due to the relative ease with which their biosynthetic genes may be identified and the resultant final products be characterized. Recent large-scale studies of the elucidation and distributions of phosphonate pathways have provided a robust landscape for deciphering the underlying biosynthetic logic. A recurrent theme in phosphonate biosynthetic pathways is the interweaving of enzymatic reactions across different routes, which enables diversification to elaborate chemically novel scaffolds. Here, we provide a few vignettes of how Nature has utilized both convergent and divergent biosynthetic strategies to compile pathways for production of novel phosphonates. These examples illustrate how common intermediates may either be generated or intercepted to diversify chemical scaffolds and provides a starting point for both biotechnological and synthetic biological applications towards new phosphonates by similar combinatorial approaches.

Role of voltage-sensitive Ca2+ channels in the in vivo dopamine release induced by the organophosphorus pesticide glufosinate ammonium in rat striatum

The possible role of voltage-sensitive calcium channels (VSCC) activation in the glufosinate ammonium (GLA)-induced dopamine release was investigated using selective VSCC blockers and the dopamine levels were measured by HPLC from samples obtained by in vivo cerebral microdialysis. While pretreatment with 10 μM flunarizine (T-type VSCC antagonist) or nicardipine (L-type VSCC antagonist) had no statistically significant effect on dopamine release induced by 10 mM GLA, pretreatment with 100 μM of both antagonists, or 20 μM ω-conotoxin MVIIC (non-selective P/Q-type VSCC antagonist) significantly decreased the GLA-induced dopamine release over 72.2%, 73%, and 70.2%, respectively. Administration of the specific antagonist of neuronal N-type VSCCs, the ω-conotoxin GVIA (20 μM), produced an almost complete blockade of in vivo dopamine release induced by GLA. These results show that GLA-induced dopamine release could be produced by the activation of a wide range of striatal VSCC located at the synaptic terminals and axons of striatal dopaminergic neurons, especially N-type VSCC.

Evaluation of the phytotoxic and antifungal activity of C17 -sesquiterpenoids as potential biopesticides

BACKGROUND

Natural products are a promising source for the development of new pesticides with alternative mechanisms of action. In this study, we evaluated the phytotoxic and antifungal activity of a novel family of natural C₁₇ -sesquiterpenoids and performed a study of the effect caused by the elimination of the α-methylene-γ-butyrolactone system and its importance to their biological activity.

RESULTS

Many tested compounds exhibited a strong phytotoxic activity. Lappalone and pertyolide B were the most potent molecules from the tested group. Lappalone displayed a strong inhibition profile against selected weed species, reaching a half-maximal inhibitory concentration (IC₅₀ ) value of 5.0 μm against Echinochloa crus-galli L. shoot and 5.7 μm against the germination rate of Amaranthus viridis L., as well as a good stimulation of the germination of Phelipanche ramosa L. Pertyolide B demonstrated excellent inhibition against Amaranthus viridis L. (IC₅₀ : 56.7, 70.3 and 24.0 μm against the root and shoot growth, and germination rate, respectively) and Allium cepa L. (representative of the Liliaceae family, with IC₅₀ values of 25.3 and 64.4 μm against root and shoot growth). Regarding the antifungal activity, pertyolide B presented significant activity against Colletotrichum fragareae and Fusarium oxysporum with a minimum inhibitory concentration of 6.6 μg μL^-1 .

CONCLUSION

The bioassays revealed that frequently the presence of the α-methylene-γ-butyrolactone system is not essential for the bioactivities of sesquiterpene lactones, and suggest that C₁₇ -sesquiterpenoids may function through a different mechanism of action not related to the widely assumed Michael addition. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genetic Analysis and Fine Mapping of ZmGHT1 Conferring Glufosinate Herbicide Tolerance in Maize (Zea mays L.)

Weed interference in the crop field is one of the major biotic stresses causing dramatic crop yield losses, and the development of herbicide-resistant crops is critical for weed control in the application of herbicide technologies. To identify herbicide-resistant germplasms, we screened 854 maize inbreed lines and 25,620 seedlings by spraying them with 1 g/L glufosinate. One plant (L336R), possibly derived from a natural variation of line L336, was identified to have the potential for glufosinate tolerance. Genetic analysis validated that the glufosinate tolerance of L336R is conferred by a single locus, which was tentatively designated as ZmGHT1. By constructing a bi-parental population derived from L336R, and a glufosinate sensitive line L312, ZmGHT1 was mapped between molecular markers M9 and M10. Interestingly, genomic comparation between the two sequenced reference genomes showed that large scale structural variations (SVs) occurred within the mapped region, resulting in 2.16 Mb in the inbreed line B73, and 11.5 kb in CML277, respectively. During the fine mapping process, we did not detect any additional recombinant, even by using more than 9500 F₂ and F₃ plants, suspecting that SVs should also have occurred between L336R and L312 in this region, which inhibited recombination. By evaluating the expression of the genes within the mapped interval and using functional annotation, we predict that the gene Zm00001eb361930, encoding an aminotransferase, is the most likely causative gene. After glufosinate treatment, lower levels of ammonia content and a higher activity of glutamine synthetase (GS) in L336R were detected compared with those of L336 and L312, suggesting that the target gene may participate in ammonia elimination involving GS activity. Collectively, our study can provide a material resource for maize herbicide resistant breeding, with the potential to reveal a new mechanism for herbicide resistance.

Visible-Light-Induced α-C(sp3)-H Phosphinylation of Unactivated Ethers under Photocatalyst- and Additive-Free Conditions

A photocatalyst- and additive-free visible-light-induced α-C(sp³)-H phosphinylation of unactivated ethers involving a C-O bond cleavage with molecular oxygen as the sole oxidant at room temperature has been achieved. This method provides a sustainable access to α-hydroxyphosphine oxides in up to 88% yield with good functional group compatibility under mild and neutral conditions (34 examples). Moreover, the subsequent two-step conversion of the resulting dihydroxy diarylphosphine oxides afforded α-phosphinylated cyclic ethers in good overall yields (10 examples).

Copper Glufosinate-Based Metal-Organic Framework as a Novel Multifunctional Agrochemical

Pesticides are agrochemical compounds used to kill pests (insects, rodents, fungi, or unwanted plants), which are key to meet the world food demand. Regrettably, some important issues associated with their widespread/extensive use (contamination, bioaccumulation, and development of pest resistances) demand a reduction in the amount of pesticide applied in crop protection. Among the novel technologies used to combat the deterioration of our environment, metal-organic frameworks (MOFs) have emerged as innovative and promising materials in agroindustry since they possess several features (high porosity, functionalizable cavities, ecofriendly composition, etc.) that make them excellent candidates for the controlled release of pesticides. Moving toward a sustainable development, in this work, we originally describe the use of pesticides as building blocks for the MOF construction, leading to a new type of agricultural applied MOFs (or AgroMOFs). Particularly, we have prepared a novel 2D-MOF (namely, GR-MOF-7) based on the herbicide glufosinate and the widely used antibacterial and fungicide Cu²⁺. GR-MOF-7 crystallizes attaining a monoclinic P2₁/c space group, and the asymmetric unit is composed of one independent Cu²⁺ ion and one molecule of the Glu^2- ligand. Considering the significant antibacterial activity of Cu-based compounds in agriculture, the potential combined bactericidal and herbicidal effect of GR-MOF-7 was investigated. GR-MOF-7 shows an important antibacterial activity against Staphylococcus aureus and Escherichia coli (involved in agricultural animal infections), improving the results obtained with its individual or even physical mixed precursors [glufosinate and Cu(NO₃)₂]. It is also an effective pesticide against germination and plant growth of the weed Raphanus sativus, an invasive species in berries and vines crops, demonstrating that the construction of MOFs based on herbicide and antibacterial/antifungal units is a promising strategy to achieve multifunctional agrochemicals. To the best of our knowledge, this first report on the synthesis of an MOF based on agrochemicals (what we have named AgroMOF) opens new ways on the safe and efficient MOF application in agriculture.

Large-scale evaluation of physical drift and volatility of 2,4-D choline in cotton: a four-year field study

BACKGROUND

Cotton with resistance to 2,4-d choline, glufosinate and glyphosate allows over-the-top use of these herbicides for postemergence weed control. Nontransgenic cotton is highly responsive to low rates of 2,4-d, causing concern among farmers when the herbicide is applied near the crop. Injury to nearby cotton following application of 2,4-d choline is sometimes blamed on volatilization of the herbicide.

RESULTS

A large-scale experiment was conducted in 2018-2021 to better understand causes of damage to nearby sensitive cotton following an application of 2,4-d choline plus glufosinate-ammonium. The herbicides were applied to 0.4 ha in the center of a 4-ha non-Enlist cotton field. At 30 min after application, air samplers were established in the treated center and outside the treated area in cardinal directions. The 72-h cumulative air concentration of 2,4-d in the swath ranged from 3.3 to 7.1 ng m^-3 , and most volatile residues (5.0-25.5 ng m^-3 ) were detected in samplers established in the downwind direction directly adjacent to the treated field. Cotton plants in three downwind transects that were covered for 30 min after application were not damaged by 2,4-d, whereas noncovered plants along the downwind transects were injured. No cotton injury occurred outside the treated area, except in the downwind direction during application even though wind direction changed after application.

CONCLUSION

2,4-d choline volatilizes, but findings show that the volatilization is not sufficient to damage cotton in the neighboring area following applications, pointing to the importance of applicators understanding wind direction/shift during the application along with proximity of sensitive crops in the downwind direction. © 2022 Society of Chemical Industry.

Prognostic value of neutrophil to lymphocyte ratio in the diagnosis of neurotoxicity after glufosinate ammonium poisoning

Neurotoxicity related to glufosinate ammonium is known to occur after a latent period of 4-60 hr following ingestion of this herbicide. However, neurotoxicity is difficult to predict in the emergency department (ED) and only a few parameters are known to be useful to indicate development of neurotoxicity. Determination of a systemic inflammation parameter such as the neutrophil to lymphocyte ratio (NLR), is a rapid and simple method which was found to be a prognostic marker in various clinical conditions such as sepsis, cardiac disorders, stroke, and cancer. Therefore, the aim of this study was to determine whether the NLR might predict neurotoxicity and be used at ED to detect neurotoxicity induced following glufosinate ammonium poisoning in admitted patients. This retrospective observational study collected data from consecutive patients diagnosed with acute glufosinate ammonium poisoning between January 2005 and December 2020. The primary outcome was development of neurotoxicity following acute glufosinate ammonium poisoning. Out of the 72 patients selected 44 patients (61.1%) exhibited neurotoxic symptoms. Neurotoxicity appeared with an approximate latent period of 12 hr. The NLR was significantly higher in the group displaying neurotoxicity. Multivariable analysis showed that the NLR was significant in predicting neurotoxicity. The NLR was independently associated with neurotoxicity initiated by glufosinate ammonium. Therefore, the use of the NLR might help clinically to readily and rapidly predict development of neurotoxicity associated with glufosinate ammonium at the ED.

Glyphosate sensing in aqueous solutions by fluorescent zinc(II) complexes of [9]aneN3-based receptors

Herein we describe the binding abilities of Zn(II) complexes of [12]aneN4- (L1) and [9]aneN3-based receptors (L2, L3) towards the herbicides N-(phosphonomethyl)glycine (glyphosate, H3PMG) and 2-amino-4-[hydroxy(methyl)phosphoryl]butanoic acid (glufosinate, H2GLU), and also aminomethylphosphonic acid (H2AMPA), the main metabolite of H3PMG, and phosphate. All ligands form stable Zn(II) complexes, whose coordination geometries allow a possible interaction of the metal center with exogenous anionic substrates. Potentiometric studies evidenced the marked coordination ability of the L2/Zn(II) system for the analytes considered, with a preferential binding affinity for H3PMG over the other substrates, in a wide range of pH values. 1H and 31P NMR experiments supported the effective coordination of such substrates by the Zn(II) complex of L2, while fluorescence titrations and a test strip experiment were performed to evaluate whether the H3PMG recognition processes could be detected by fluorescence signaling.