Mesotrione Research Articles

Construction of Immobilized Laccase System Based on ZnO and Degradation of Mesotrione.

Mesotrione (MES) is a new environmental pollutant. Some reports have indicated that microbial enzymes could be utilized for MES degradation. Laccase is a green biocatalyst whose potential use in environmental pollutant detoxification has been considered limited due to its poor stability and reusability. However, these issues may be addressed using enzyme immobilization. In the present study, we sought to optimize conditions for laccase immobilization, to analyze and characterize the characteristics of the immobilized laccase, and to compare its enzymatic properties to those of free laccase. In addition, we studied the ability of laccase to degrade MES, and analyzed the metabolic pathway of MES degradation by immobilized laccase. The results demonstrated that granular zinc oxide material (G-ZnO) was successfully used as the carrier for immobilization. G-ZnO@Lac demonstrated the highest recovery of enzyme activity and exhibited significantly improved stability compared with free laccase. Storage stability was also significantly improved, with the relative enzyme activity of G-ZnO@Lac remaining at about 54% after 28 days of storage (compared with only 12% for free laccase). The optimal conditions for the degradation of MES by G-ZnO@Lac were found to be 10 mg, 6 h, 30 °C, and pH 4; under these conditions, a degradation rate of 73.25% was attained. The findings of this study provide a theoretical reference for the laccase treatment of 4-hy-droxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide contamination.

Genome-wide characterization and expression of Oryza sativa AP2 transcription factor genes associated with the metabolism of mesotrione

BackgroundThe APETALA2 (AP2) transcription factor (TF) superfamily, one of the largest gene families in plants, plays an essential role in regulating plant growth and their stress responses. However, the role of AP2 in rice under pesticide stress remains unclear. To investigate the characteristics and functions of the rice AP2 gene family under pesticide stress, the expression of 105 AP2-coding genes and 26 AP2 differentially expressed genes (DEGs) were identified in mesotrione (MTR)-treated rice transcriptome datasets.ResultsThree subfamilies of the AP2 gene family (AP2/ERF, RAV, and soloists) were identified using sequence alignment and phylogenetic analysis. Chromosome location analysis revealed that the 26 rice AP2 DEGs were unevenly distributed on 10 of the 12 rice chromosomes, and segmental duplication contributed to the expansion of Oryza sativa AP2 (OsAP2) gene family. Collinearity analyses demonstrated that rice AP2 genes displayed 16 orthologous gene pairs, and 12 and 26 orthologous gene pairs were shared of Arabidopsis and soybean, respectively. In addition, rice AP2 genes featured various gene structures, cis-elements, motif compositions, and conserved domains that allowed them to encode genes that elicit biotic and abiotic stress responses. An analysis of docking between MTR and six AP2 DEGs revealed amino acid residues involved in MTR binding. Quantitative reverse transcription–polymerase chain reaction verified that several AP2 genes were preferentially expressed during MTR-induced stress. The roles of OsAP2 proteins in MTR metabolism were further supported by protein–protein interaction network analysis, which illustrated how these proteins interact with target proteins.ConclusionThe initial findings of this study define the features of the OsAP2 superfamily and offer important tools for functional analyses of OsAP2 genes implicated in the metabolism of MTR.Graphical

The cathodically pretreated boron-doped diamond electrode as an environmentally friendly electrochemical tool for the detection and monitoring of mesotrione in food samples

Excessive pesticide use can harm human health, making it essential to develop new techniques to monitor hazardous pesticides in food. Our study focuses on detecting mesotrione (MST) using an unmodified boron-doped diamond (BDD) electrode. This was the first application of cathodically pretreated BDD electrode for the detection of MST, based on its oxidation at a high potential value of +1.4 V. We theoretically examined the oxidation mechanism of MST trough the utilization of density functional theory (DFT) methodology. The utilized DPV method achieved a detection limit of 0.45 μM and showed satisfactory selectivity. The practical application of this method was demonstrated by examining corn-based food products. To ensure practical application of the method, MST was deliberately added to the samples to evaluate the accuracy of the proposed method. The effectiveness of the method was confirmed by using HPLC method. This environmentally-friendly approach can establish a solid foundation for future use in food analysis.

Tb(III)-functionalized covalent organic framework for fluorescence detection of sodium dehydroacetate, 2-methoxyaceticacid and mesotrione and adsorption application

Hazardous substances are often found in various forms in different environments, so testing for different types of hazardous substances is necessary. In particular, the removal of pollutants from the water environment is also of great interest. In this study, TGH+-PD@Tb (1@Tb) is successfully prepared for the fluorescence detection of sodium dehydroacetate (NADH) by “turn-on” mode. Continuously, the selective fluorescence detections of 2-methoxyaceticacid (Maa) and mesotrione (MST) are accomplished using the solution (1@Tb@NADH) with green fluorescence by “turn-off” mode. In deionized water, the limits of detection of NADH, Maa and MST are 1.8 μM, 0.10 μM and 0.046 μM, respectively. Meanwhile, based on selectivity and anti-interference experiments, 1@Tb and 1@Tb@NADH maintain the ability to detect NADH, Maa and MST in their own environments of existence (bread, serum and lake water). In further exploration of the mechanism, we find that the three substrates exhibited different response mechanisms, namely antenna effect of NADH, photoinduced electron transfer (PET) of Maa, and inner filter effect (IFE) of MST. Additionally, 1@Tb also shows good adsorption effect for MST, and the maximum adsorption capacity is 470.8 mg/g, providing reference value for MST removal from lake water.

Synergies of WO3 and Co3O4 intercalated ball milling exfoliated graphene 3D helix electrocatalyst: A highly sensitive electrochemical detection of mesotrione herbicide in vegetable samples

In the booming global population, monitoring of mesotrione (MTN) like agricultural pollutants is crucial for human safety. Herein, the research reports the synthesis of tungsten trioxide (WO3) and cobalt oxide (Co3O4) nanostructures intercalated ball milling exfoliated graphene (WO3/Co3O4/graphene) 3D helix electrocatalyst for the electrochemical detection of MTN herbicide. The proposed WO3/Co3O4/graphene sensor material achieved a wide range of MTN detection from 0.001 µM to 1885 µM. In addition, the estimated limit of sensing and sensitivity values are 0.42 nM and 0.802 µAµM−1 cm−2 respectively. The real sample experiment was accomplished in MTN-added vegetables (corn, sugar cane, tomato, green soybean) and environmental samples (sewage water, river water). At most, the recorded minimum MTN response recovery in vegetables and water samples is about 95% and 98% respectively. Furthermore, the designed sensor electrode achieved storage stability of 98.7% after three weeks.

Utilizing differences in bTH tolerance between the parents of two-line hybrid rice to improve the purity of hybrid rice seed.

Two-line hybrid rice based on Photoperiod/thermo-sensitive genic male sterile (P/TGMS) lines has been developed and applied widely in agriculture due to the freedom in making hybrid combinations, less difficulty in breeding sterile lines, and simpler procedures for breeding and producing hybrid seed. However, there are certain risks associated with hybrid seed production; if the temperature during the P/TGMS fertility-sensitive period is lower than the critical temperature, seed production will fail due to self-pollination. In a previous study, we found that the issue of insufficient purity of two-line hybrid rice seed could be initially addressed by using the difference in tolerance to β-triketone herbicides (bTHs) between the female parent and the hybrid seeds. In this study, we further investigated the types of applicable herbicides, application methods, application time, and the effects on physiological and biochemical indexes and yield in rice. The results showed that this method could be used for hybrid purification by soaking seeds and spraying plants with the bTH benzobicylon (BBC) at safe concentrations in the range of 37.5-112.5 mg/L, and the seeds could be soaked in BBC at a treatment rate of 75.0 mg/L for 36-55 h without significant negative effects. The safe concentration for spraying in the field is 50.0-400.0 mg/L BBC at the three-leaf stage. Unlike BBC, Mesotrione (MST) can only be sprayed to achieve hybrid purification at concentrations between 10.0 and 70.0 mg/L without affecting yield. The three methods of hybrid seed purification can reach 100% efficiency without compromising the nutritional growth and yield of hybrid rice. Moreover, transcriptome sequencing revealed that 299 up-regulated significant differentially expressed genes (DEGs) in the resistant material (Huazhan) poisoned by BBC, were mainly enriched in phenylalanine metabolism and phenylpropanoid biosynthesis pathway, it may eliminate the toxic effects of herbicides through this way. Our study establishes a foundation for the application of the bTH seed purification strategy and the three methods provide an effective mechanism for improving the purity of two-line hybrid rice seeds.

An emergent electrochemical sensor based on spinel zinc manganese oxide decorated on amine-functionalized boron nitride for enhanced electrochemical determination of herbicide mesotrione

Mesotrione (MTO) is a herbicide that is commonly used in agriculture; unfortunately, this chemical often makes its way into aqueous environments. In this study, an MTO sensor was fabricated based on spinel zinc manganese oxide (ZnMn2O4, ZMO) nanoparticles (NPs) and an amine-functionalized boron nitride (NH2-BN) composite. ZMO was synthesized using a coprecipitation technique, and NH2-BN was prepared by a urea-assisted ultrasonication/stirring method. The nanocomposite of ZMO NPs/NH2-BN was prepared using the sonication method. The crystallinity, oxidation states, and functionality of the catalysts were investigated using physiochemical characterization techniques: powder X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. In addition, the surface morphology and topology of the ZMO NPs/NH2-BN composite were analyzed by field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The ZMO NPs/NH2-BN/glassy carbon electrode (GCE) exhibited a well-resolved MTO reduction peak in cyclic voltammetry experiments due to the synergetic effect between the aggregated ZMO NPs and NH2-BN. In addition, ZMO NPs/NH2-BN/GCE exhibited a low limit of detection of 1.5 nM, high sensitivity (1.791 µA µM−1 cm−2), and broad linear ranges (0.01–12.51 µM and 18.51–1777.51 µM). A ZMO NPs/NH2-BN/GCE sensor prototype was used to effectively detect MTO in environmental water samples with good recovery.

Adjuvant and nozzle effects on weed control using mesotrione and rimsulfuron plus thifensulfuron-methyl

Limitations on the available herbicide portfolio for weed control have led to weed control failures. Application techniques such as proper selection of nozzle types, adjuvants, and herbicide selection have been suggested as one of the ways to maximize efficacy. The launch of HPPD (hydroxyphenylpyruvate dioxygenase)-tolerant crops will increase HPPD herbicide applications, while effective herbicide tank mixtures might prolong herbicide resistance evolution. Therefore, a greenhouse experiment was conducted to evaluate the effects of mesotrione (MES) and rimsulfuron plus thifensulfuron-methyl (RIMTHIF) in tank mixtures with five adjuvants sprayed with three different nozzle types, XR (Extended Range), AIXR (Air Induction Extended Range), and TTI (Turbo TeeJet Induction), on weed control. Five weed species were tested: common lambsquarters (Chenopodium album L.), velvetleaf (Abutilon theophrasti Medic.), common waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer), Palmer amaranth (Amaranthus palmeri S. Wats.), barnyardgrass (Echinochloa crus-galli (L.) P. Beauv.), and a grain sorghum (Sorghum bicolor (L.) Moench) crop. A dose‒response study using MES and RIMTHIF was conducted to estimate the effective dose to reduce the aboveground biomass by 50% from the nontreated control (ED50). Another study was conducted to evaluate the efficacy of MES and RIMTHIF in tank mixtures with five adjuvants (ammonium sulfate – AMS, crop oil concentrate – COC, drift reducing adjuvant – DRA, methylated seed oil – MSO, and nonionic surfactant – NIS) sprayed with three nozzle types (XR, AIXR, and TTI). The selected nozzles influenced velvetleaf, common lambsquarters, and sorghum, indicating the possibility of applying herbicides with Coarser sprays, avoiding off-target movement. Our findings suggest adjuvants are an essential factor for improving weed control over the active ingredient, up to 18.7% and 38.3% for MES and RIMTHIF, respectively. Barnyardgrass biomass reduction was greater than 98% with RIMTHIF in tank mixtures with COC and MSO compared to 65% when applied alone. Common lambsquarters had 52.1% biomass reduction when RIMTHIF was sprayed alone, while adding adjuvants to the tank-mixture resulted in biomass reduction ranging from 60.1% (COC) to 94.1% (AMS). Velvetleaf biomass reduction was 98% when the MES and RIMTHIF mixture was applied with the addition of MSO, while 87% without the adjuvant added. These results indicate that adding adjuvants in herbicide solution can improve herbicide efficacy (COC and MSO for barnyardgrass; NIS, AMS, and MSO for velvetleaf; and NIS, COC, and MSO for common lambsquaters).

Sonochemical construction of hierarchical strontium doped lanthanum trisulfide electrocatalyst: An efficient electrode for highly sensitive detection of ecological pollutant in food and water.

Herbicides are used constantly in agriculture to enhance productivity across the globe. This herbicide monitoring requires utmost importance since its high dose leads to ecological imbalance and a negative impact on the environment. Moreover, a quantification of toxic herbicide is one of the important problems in the food analysis. In this work, deals with the development of a simple, and facile one-pot sonochemical synthesis of strontium doped La2S3 (Sr@La2S3). Morphological and structural characterization confirms the doping of Sr@La2S3 to generate a hierarchical layered structure. The electrochemical performance of modified with rotating disk electrode (RDE) using Sr@La2S3 composite is high, compared to La2S3 and bare electrodes towards the quantitative detection of mesotrione (MTO) in phosphate buffer. Sr@La2S3/RDE showed good sensitivity for MTO detection and it exhibit a range of 0.01-307.01μM and limit of detection of 2.4nM. Besides, the selectivity of fabricated electrode is high as it can electrochemically reduce MTO particularly, even in the presence of other chemicals, biological molecules and inorganic ions. The repeatability of MTO detection is high even after 30days with a lower RSD values. Hence, simple fabrication of Sr@La2S3/RDE could be a novel electrode for the sensitive, selective, and reproducible determination of herbicides in real-time applications.

Effect of bismuth doping on zircon-type gadolinium vanadate: Effective electrocatalyst for determination of hazardous herbicide mesotrione

Pesticides are used to promote the growth of plants and crops by killing weeds and other pests. On the other hand, overused and unused pesticides can leach into groundwater and agricultural lands, easily contaminating water, air, and soil resources. Doping with metal ions is an effective method to improve the catalytic activity of potential electrode materials. In the present study, an electrochemical sensor based on Bi3+-doped gadolinium vanadate nanoparticles (GVB NPs) was fabricated for sensitive and selective detection of harmful pesticide mesotrione (MST). The crystalline nature, functional groups, and elemental composition of the prepared electrocatalysts were confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Field-emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) showed that the undoped gadolinium vanadate had a rice-like nanostructure and was designated as GV NRs, while GVB had the morphology of nanoparticles. The fabricated electrode exhibited a well-resolved MST reduction peak in cyclic voltammetry and linear sweep voltammetry (LSV). Bismuth doping effectively enhanced the MST reduction and produced a stronger cathodic current response than bare and GV NRs-modified GCE. Moreover, GVB NPs/GCE show a nanomolar detection limit of 45 nM with a sensitivity of 0.43 μA μM−1 cm−2. The proposed sensor showed good repeatability, reproducibility, and stability in LSV analysis. The fabricated MST sensor was successfully applied to the analysis of real samples (river water and corn) with good recovery results.

Identification, characterization and expression of rice (Oryza sativa) acetyltransferase genes exposed to realistic environmental contamination of mesotrione and fomesafen

The plant acetyltransferases (ACEs) belong to a super family of proteins that contribute to secondary metabolisms and involve various abiotic and biotic stress responses. However, how rice ACEs respond to toxic agrochemicals is largely unknown. This study demonstrates that 86 and 83 genes coding ACEs in the transcriptome profiling were expressed under mesotrione (MTR) and fomesafen (FSA) exposure, respectively. Of these, 18 and 8 ACE differentially expressed genes (DEGs) were identified in MTR- and FSA-exposed rice transcriptome datasets. Some of the ACE genes were validated by quantitative RT-PCR analysis. Analysis of biochemical properties of ACEs revealed that many genes have various cis-elements and structural domain which may cope with a variety of biotic and abiotic stress responses and detoxification of xenobiotics. Moreover, the ACE activities in rice were induced under MTR and FSA exposure and reached out to the highest value at the 0.1 mg L−1. The ACE activities in the MTR and FSA treated roots were 2.6 and 3.5 fold over the control and those in shoots with MTR and FSA were 4.0 and 26.1 fold over the control, respectively. These results indicate that the ACE-coding genes can respond to the MTR and FSA stress by increasing their transcriptional level, along with the enhanced specific ACE protein activities in rice tissues.

On the use of inhibitors of 4-hydroxyphenylpyruvate dioxygenase as a vector-selective insecticide in the control of mosquitoes.

Blood-sucking insects incorporate many times their body weight of blood in a single meal. Because proteins are the major component of vertebrate blood, its digestion in the gut generates extremely high concentrations of free amino acids. Previous reports showed that the tyrosine degradation pathway plays an essential role in adapting these animals to blood feeding. Inhibition of 4-hydroxyphenylpyruvate dioxygenase (HPPD), the rate-limiting step of tyrosine degradation, results in the death of insects after a blood meal. Therefore, it has been suggested that compounds that block the catabolism of tyrosine could act selectively on blood-feeding insects. Here, we evaluated the toxicity against mosquitoes of three HPPD inhibitors currently used as herbicides and in human health. Of the compounds tested, nitisinone (NTBC) proved to be more potent than mesotrione (MES) and isoxaflutole (IFT) in Aedes aegypti. NTBC was lethal to Ae. aegypti in artificial feeding assays [median lethal dose (LD50 ): 4.53 μm] and in topical application (LD50 : 0.012 nmol/mosquito). NTBC was also lethal to Ae. aegypti populations that were resistant to neurotoxic insecticides, and to other mosquito species (Anopheles and Culex). HPPD inhibitors, particularly NTBC, represent promising new drugs for mosquito control. Because they affect only blood-feeding organisms, they represent a safer and more environmentally friendly alternative to conventional neurotoxic insecticides. © 2021 Society of Chemical Industry.

Design and Fabrication of Yttrium Ferrite Garnet-Embedded Graphitic Carbon Nitride: A Sensitive Electrocatalyst for Smartphone-Enabled Point-of-Care Pesticide (Mesotrione) Analysis in Food Samples.

As the use of pesticides in agriculture is increasing at an alarming rate, food contamination by pesticide residues is becoming a huge global problem. It is essential to develop a sensitive and user-friendly sensor device to quantify trace levels of pesticide and herbicide residues in food samples. Herein, we report an electrocatalyst made up of yttrium iron garnet (Y3Fe5O12; YIG) and graphitic carbon nitride (GCN) to attain picomolar-level detection sensitivity for mesotrione (MTO), which is a widely used herbicide in agriculture. First, YIG was prepared by a hydrothermal route; then, it was loaded on GCN sheets via a calcination method. The surface structures, composition, crystallinity, and interfacial and electrocatalytic properties of the YIG and YIG/GCN were analyzed. As the YIG/GCN displayed better surface and catalytic properties than YIG, YIG/GCN was modified on a screen-printed carbon electrode to fabricate a sensor for MTO. The YIG/GCN-modified electrode displayed a detection limit of 950 pM for MTO. The method was demonstrated in (spiked) fruits and vegetables. Then, the modified electrode was integrated with a miniaturized potentiostat called KAUSTat, which can be operated wirelessly by a smartphone. A first smartphone-based portable sensor was demonstrated for MTO that is suitable for use in nonlaboratory settings.

Comprehensive analyses of degradative enzymes associated with mesotrione-degraded process in rice for declining environmental risks

Mesotrione (MTR) is a highly effective pesticide widely used for weeding in farmland. Overload of MTR in agricultural soils may result in environmental problems. To evaluate the potential contamination of MTR in environments, a better understanding of the MTR degradation process and mechanisms in crops is required. This study investigated the impact of MTR on growth and toxicological responses in rice (Oryza sativa). The growth of rice tissues was significantly compromised with increasing MTR concentrations. RNA-sequencing combined with HRLC-Q-TOF-MS/MS analysis identified many transcriptional components responsible for MTR degradation. Four libraries composed of root and shoot tissues exposed to MTR were RNA-sequenced in biological triplicate. Compared to –MTR, treatment with environmentally realistic MTR concentration upregulated 1995 genes in roots and 326 genes in shoots. Gene enrichment revealed many MTR-degradative enzymes functioning in resistance to environmental stress and molecular metabolism of xenobiotics. Specifically, many differentially expressed genes are critical enzymes like cytochrome P450, glycosyltransferases, methyltransferase, glutathione S-transferases and acetyltransferase involved in the process. To evidence MTR degradative metabolisms, HRLC-Q-TOF-MS/MS was used to characterize eight metabolites and five conjugates in the pathways involving hydrolysis, reduction, glycosylation, methylation or acetylation. The precise association between the specific MTR-degraded products and enhanced activities of its corresponding enzymes was established. This study advanced our understanding of the detailed MTR degradative mechanisms and pathways, which may help engineer genotypes to facilitate MTR degradation in the paddy crop.

Profiling and fingerprinting strategies to assess exposure of edible plants to herbicides

Raphanus sativus var. longipinnatus, was exposed under experimental conditions to herbicides: rimsulfuron (RIM), administrated as (1) pure substance, (2) in commercially available formulation (RIMEL), (3) its degradation product: 4,6-dimethoxypyrimidin-2-amine (2ADP), (4) mesotrione (MES), (5) sulcotrione (SUL). Profiling and fingerprinting strategies, conducted by LC-MS/MS-FL, were employed to find markers of plant exposure to herbicide stress. The presence ofRIM metabolite in the tissues of plant exposed to this herbicide proved that it is necessary to determine both parent compound and its by-products to obtain reliable information on plant exposure to agrochemicals. A higher content of normetanephrine (NMN) (18–175%) and lower content of tyramine (TYR) (49–75%) and epinephrine (E) (75–83%) was observed in plant tissues exposed to RIM and 2ADP in comparison to blank sample. Therefore, NMN, TRY and E may be considered as markers of plant response to RIM. Non-target analysis enables to recognize the type of herbicide used during cultivation.

A sepiolite-based formulation for slow release of the herbicide mesotrione

A slow release formulation (SRF) of the herbicide mesotrione (MS) [2-(4-mesyl-2-nitrobenzoyl)cyclohexane-1,3-dione] was designed for extended weed control relative to that of conventional formulations. The SRF was designed by incorporating the herbicide in micelles formed by the fatty amine ethoxylated surfactant Ethomeen T/15 (ET15) followed by their further sorption on the clay mineral sepiolite. The content of active substance (a.s.) was very high, 16.8% w.w. The surfactant per se was adsorbed by developing surface aggregates on sepiolite's surface. FTIR spectroscopy and zeta potential measurements demonstrated that electrostatic interactions were responsible of the sorption of MS by using micelles loaded with the herbicide, modifying the conformation of ET15 on sepiolite. Toxicity assays by using Microtox® tests yielded a value of IC50 for the SRF (52.6 ± 3.6 mg L−1) that was one order of magnitude higher than that reported for the commercial formulation Callisto® (1.1 ± 0.1 mg L−1). In vitro water release experiments stated that the release of MS was a controlled-diffusion process. Application of SRF and Callisto® as post-emergence in field trials of maize showed that after 10 days of treatment (DAT), the amount in the soil of the herbicide from the SRF was about two-fold higher than that of Callisto®, with a larger accumulation (42% of the total) in the upper soil layer (0–10 cm depth). No significant differences in soil accumulation at longer times and in the crop yield were observed. Consequently, the use of the designed sepiolite-based formulation significantly reduced MS leaching over the conventional formulation while maintaining the desired bioactivity for weed control.

Potential application of Pistia stratiotes for the phytoremediation of mesotrione and its degradation products from water

The aim of the present work is to estimate remediation potential of Pistia stratiotes, its ability to uptake mesotrione (MES) - one of the most frequently used herbicides, and its main degradation products: 2-amino-4-methylsulfonyl benzoic acid (AMBA) and 4-methylsulfonyl-2-nitrobenzoic acid (MNBA). This research focuses on model experiments performed under laboratory conditions. The results show that Pistia stratiotes can uptake up to 75% of degradation products from 1 L of surface water samples polluted with 0.4 µg/L of each analyte during 7 days without significant phytotoxic effect. Under the same experimental conditions, the effectiveness of mesotrione sorption is in the range of 42–58%. The phytotoxicity of this compound is higher in comparison to its degradation products (decrease of chlorophyll concentration in plant tissues exposed to MES 27–32% vs 4–13% in case of exposition to AMBA and MNBA). The adequate nutrition of the plants is crucial to their well-being and thus the sorption of pollutants.

Quantifying Resistance to Isoxaflutole and Mesotrione and Investigating Their Interactions with Metribuzin POST in Waterhemp (Amaranthus tuberculatus)

AbstractGreenhouse experiments were conducted to quantify resistance levels to the 4-hydroxyphenyl-pyruvate dioxygenase (HPPD)-inhibiting herbicides mesotrione (MES) and isoxaflutole (IFT) in NEB (Nebraska HPPD- and atrazine-resistant) and SIR (Stanford, IL, HPPD- and atrazine-resistant) waterhemp [Amaranthus tuberculatus(Moq.) J. D. Sauer] populations. These populations differ in their field-use histories and resistance levels to MES. Foliar growth responses were compared with ACR (HPPD sensitive; metabolic atrazine-resistant) and SEN (sensitive to HPPD and photosystem II [PSII] inhibitors). A greenhouse dose–response study was conducted with each herbicide at two POST timings: early (EPOST) (5 cm; 4 to 5 true leaves) and POST (10 cm; 8 to 9 true leaves). At the EPOST timing, SIR was 10-fold resistant to IFT and 32-fold resistant to MES, while NEB was 4-fold resistant to IFT and 7-fold resistant to MES when compared with ACR. At the POST timing, SIR was 17-fold resistant to IFT and 21-fold resistant to MES, while NEB was 3-fold resistant to IFT and 7-fold resistant to MES when compared with ACR. Results overall indicated greater fold-resistance levels to MES relative to IFT at each timing. However, POST treatments to SIR showed contrasting effects on resistance levels relative to EPOST. To investigate potential management strategies for resistantA. tuberculatuspopulations, a POST interaction study was conducted using combinations of metribuzin and either IFT or MES. A metribuzin rate (191 g ai ha−1) causing an approximately 20% biomass reduction was chosen for interaction studies and combined with varying rates of either IFT or MES. Results indicated 52.5 g ai ha−1of MES combined with metribuzin displayed a synergistic effect on biomass reduction in SIR. However, other combinations of either MES or IFT and metribuzin resulted in additive effects on biomass reduction in both HPPD-resistant populations. These results provide insights into the joint activity between HPPD and PSII inhibitors for controlling metabolism-based, multiple herbicide–resistantA. tuberculatus.

Mesotrione herbicide does not cause genotoxicity, but modulates the genotoxic effects of Atrazine when assessed in mixture using a plant test system (Allium cepa)

Mesotrione (MES) is an herbicide from the triketone family and has been used as an alternative to Atrazine (ATZ), which was banned in some countries due to its toxicity to non-target organisms. Despite being considered an eco-friendly herbicide, data from the literature about the harmful effects of MES in its pure form and/or in combination with other herbicides is still scarce. Aimed at assessing the potential of MES to induce cell death and DNA damage, seeds of Allium cepa (higher plant, monocotyledon) were exposed to this herbicide, pure and in mixture with ATZ, and the number of dividing cells (cytotoxicity), chromosomal aberrations (CA, genotoxicity) and micronuclei (MN, mutagenicity) were then quantified. The pure MES (1.8 to 460 μg/L) did not show either cytotoxicity or genotoxicity/mutagenicity under the tested conditions. The genotoxicity of ATZ (1.5 to 400 μg/L), previous reported in the literature, was confirmed herein. The assessment of MES + ATZ mixtures (1.8 + 1.5; 7 + 6.25; 30 + 25 μg/L, respectively) showed that MES, at low concentrations, enhance the genotoxicity of ATZ (potentiation), since the significant frequencies of CA and MN were greater than the ones expected in additive effects. Taking together, MES in its pure form seems to be a safe alternative to ATZ regarding the capacity to damage (at cellular and DNA levels) non-target plants (Monocots); however, MES in combination with ATZ appeared to act as a co-mutagen at low concentrations.

Electrochemical determination of mesotrione and its degradation products on glassy carbon electrode

ABSTRACTA simple, fast and sensitive analytical method was developed for the quantification of herbicide mesotrione (MES) and its degradation products: 4-(methylsulfonyl)-2-nitrobenzoic acid (MNBA) and 2-amino-4-(methylsulfonyl) benzoic acid (AMBA) using differential pulse voltammetry (DPV). Voltammetric measurements were performed using glassy carbon electrode (GCE). Potential range, pH of the electrolyte and the scan rate were optimised to achieve the lowest detection limits of analytes. The optimal conditions were obtained in a Britton–Robinson (BR) buffer at pH 4.0 for MNBA and at pH 6.0 for MES and AMBA, with the scan rate 0.08 V/s. The potential V for (1) nitro and carbonyl groups of MES, (2) nitro group of MNBA and (3) amino group of AMBA, obtained under optimised conditions, was plotted as a function of a peak current (I). The I(V) dependencies were measured for the following concentration ranges: 0.5–5.0 µM for the nitro group of MES and MNBA, 0.75–5.0 µM and 0.50–8.5 µM for the carbonyl groups of MES, and 0.25–8.5 µM for amino group of AMBA; whereas, the limit of detection was in range 0.07–0.23 µM (20–80 µg/L). The proposed method is the first one that allows the determination of both MES and its degradation products. The practical applicability of these newly developed voltammetric methods was verified by direct determination of MES and its degradation products in model samples of drinking and surface water.