Uptake, Translocation, and Subcellular Distribution of Azoxystrobin in Wheat Plant ( Triticum aestivum L.)

Unveiling the potential: exploring the efficacy of complex III inhibitors in fungal disease control

Phytopathogenic fungi are a key challenge to maximizing crop yield and quality for a growing global population. In this review, we give an overview of representative compounds that inhibit complex III, also known as bc1 complex, covering quinone inside inhibitors, quinone outside inhibitors, and quinone inside and outside inhibitors via the stigmatellin binding mode. Novel solutions to the escalating problem of resistance are still required, therefore compounds with alternative scaffolds, alternative docking modes, different mechanisms of action and improved efficacy against complex III necessitate ongoing research. © 2024 Society of Chemical Industry.

Co-exposure with Copper Alters the Uptake, Accumulation, Subcellular Distribution, and Biotransformation of Organophosphate Triesters in Rice (Oryza sativa L.)

This study investigated the uptake pathways, acropetal translocation, subcellular distribution, and biotransformation of OPEs by rice (Oryza sativa L.) after Cu exposure. The symplastic pathway was noted as the major pathway for the uptake of organophosphate triesters (tri-OPEs) and diesters (di-OPEs) by rice roots. Cu exposure enhanced the accumulation of tri-OPEs in rice roots, and such enhancement was positively correlated with Cu concentrations, attributing to the Cu-induced root damage. The hydrophilic Cl-OPEs in the cell-soluble fraction of rice tissues were enhanced after Cu exposure, while the subcellular distributions of alkyl- and aryl-OPEs were not affected by Cu exposure. Significantly higher biotransformation rates of tri-OPEs to di-OPEs occurred in leaves, followed by those in stems and roots. Our study reveals the mechanisms associated with the uptake, translocation, and biotransformation of various OPEs in rice after Cu exposure, which provides new insights regarding the phytoremediation of soils cocontaminated with heavy metal and OPEs.

Insights into the Enantiomeric Uptake, Translocation, and Distribution of Triazole Chiral Pesticide Mefentrifluconazole in Wheat (Triticum aestivum L.)

The uptake, translocation, and accumulation of mefentrifluconazole (MFZ), an innovative chiral triazole fungicide, in plants at the enantiomeric level are still unclear. Herein, we investigated the patterns and mechanisms of enantiomeric uptake, bioaccumulation, and translocation through several experiments. Rac-MFZ shows the strongest uptake and bioaccumulation capacity in wheat compared with its enantiomers, while S-(+)-MFZ has the highest translocation potential. Molecular docking provided evidence of the stronger translocation ability of S-(+)-MFZ than R-(-)-MFZ. Split-root experiments showed that MFZ and its enantiomers could undergo long-distance transport within the wheat. Active transport or facilitated and simple diffusion may be involved in the wheat uptake of MFZ. The limited acropetal translocation capability of MFZ may be attributed to the dominant uptake pathway of apoplastic. The concentrations of Rac-MFZ in different subcellular fractions varied greatly. In summary, this study provides novel insights for further understanding the behaviors of MFZ and its enantiomers in plants.

Accumulation, translocation, metabolism and subcellular distribution of mandipropamid in cherry radish: A comparative study under hydroponic and soil-cultivated conditions

The accumulation and transportation of pesticides in plants can provide valuable insights to assess potential risks and ensure food safety. The uptake and downward translocation of mandipropamid were examined in hydroponic and soil-cultivated cherry radishes. The uptake of mandipropamid in cherry radish was rapid (bioconcentration factors of 1.1-10.7), whereas the downward translocation was limited (translocation factors of 0.1-0.9). The subcellular distribution results indicated a predominant accumulation in solid fractions of cherry radish (proportions of 52.9-98.7%), potentially because of the hydrophobicity (log Kow of 3.2) of mandipropamid. Owing to the decrease in half-life (>10%), the cultivation of cherry radish enhanced the dissipation of mandipropamid in both nutrient solutions (without stereoselectivity) and soils (with stereoselectivity). In addition, eleven metabolites and three pathways are proposed. This study provides valuable insights for the varying extent of translocation and proper utilization and safety evaluation of mandipropamid in crops.

PFOA-contaminated soil remediation: a comprehensive review

Soil and groundwater contamination has been raised as a concern due to the capability of posing a risk to human health and ecology, especially in facing highly toxic and emerging pollutants. Because of the prevalent usage of perfluorooctanoic acid (PFOA), in industrial and production processes, and subsequently the extent of sites contaminated with these pollutants, cleaning up PFOA polluted sites is paramount. This research provides a review of remediation approaches that have been used, and nine remediation techniques were reviewed under physical, chemical, and biological approaches categorization. As the pollutant specifications, environmental implications, and adverse ecological effects of remediation procedures should be considered in the analysis and evaluation of remediation approaches, unlike previous research that considered a couple of PFAS pollutants and generally dealt with technical issues, in this study, the benefits, drawbacks, and possible environmental and ecological adverse effects of PFOA-contaminated site remediation also were discussed. In the end, in addition to providing sufficient and applicable understanding by comprehensively considering all aspects and field-scale challenges and obstacles, knowledge gaps have been found and discussed.

Unveiling the absorption, translocation, and metabolism of penthiopyrad in pakchoi under hydroponic and soil-cultivated conditions

The efficient use of pesticides has long been a topic of public concern, necessitating a thorough understanding of their movement in plants. This study investigates the translocation and distribution of penthiopyrad in pakchoi plants cultivated both in hydroponic and soil-cultivated conditions. Results indicate that penthiopyrad predominantly accumulates in the roots, with concentrations of 11.3-53.9 mg/kg following root application, and in the leaves, with concentrations of 2.0-17.1 mg/kg following foliar application. The bioconcentration factor exceeded 1, with values ranging from 1.2 to 23.9 for root application and 6.4 to 164.0 for foliar application, indicating a significant role in the absorption and accumulation processes. The translocation factor data, which were <1, suggest limited the translocations within pakchoi plants. The limitation may be attributed to the hydrophobic properties of penthiopyrad (log Kow = 3.86), as evidenced by its predominant distribution in the subcellular solid fractions of pakchoi tissues, accounting for 93.1% to 99.5% of the total proportion. Six metabolites (753-A-OH, M12, 754-T-DO, M11, PCA, and PAM) were identified in this study as being formed during this process. These findings provide valuable insights into the absorption, translocation, and metabolism of penthiopyrad in pakchoi.

Border cell population size and oxidative stress in the root apex of Triticum aestivum seedlings exposed to fungicides

Fungicides reduce the risk of mycopathologies and reduce the content of mycotoxins in commercial grain. The effect of fungicides on the structural and functional status of the root system of grain crops has not been studied enough. In this regard, we studied the phytocytotoxic effects tebuconazole (TEB) and epoxiconazole (EPO) and azoxystrobin (AZO) in the roots of Triticum aestivum seedlings in hydroponic culture. In the presence of EPO and AZO (but not TEB) inhibition of the root growth was accompanied by a dose-dependent increase in the content of malondialdehyde, carbonylated proteins, and proline in roots. TEB was characterized by a dose-dependent decrease in the total amount of border cells (BCs) and the protein content in root extracellular trap (RET). For EPO and AZO, the dose curves of changes in the total number of BCs were bell-shaped. AZO did not affect the protein content in RET. The protein content in RET significantly decreased by 3 times for an EPO concentration of 1 µg/mL. The obtained results reveal that the BC-RET system is one of the functional targets of fungicides in the root system of wheat seedlings. Studied fungicides induce oxidative stress and structural and functional alterations in the BC-RET system that can affect their toxicity to the root system of crops.

Urban-use pesticides in stormwater ponds and their accumulation in biofilms

Stormwater ponds frequently receive urban runoff, increasing the likelihood of pesticide contamination. Biofilms growing in surface waters of these ponds are known to accumulate a range of aquatic contaminants, paradoxically providing both water purification services and potentially posing a threat to urban wildlife. Thus, sampling biofilms in stormwater ponds may be a critical and biologically relevant tool for characterizing pesticide contamination and toxicity in urban environments. Here, we aimed to investigate pesticide occurrences at 21 stormwater ponds in Brampton, ON, one of Canada's fastest growing municipalities, and quantify their accumulation in biofilm. Over nine weeks, we collected time-integrated composite water and biofilm samples for analysis of ∼500 current-use and legacy pesticides. Thirty-two pesticide compounds were detected across both matrices, with 2,4-D, MCPA, MCPP, azoxystrobin, bentazon, triclopyr, and diuron having near-ubiquitous occurrences. Several compounds not typically monitored in pesticide suites (e.g., melamine and nicotine) were also detected, but only in biofilms. Overall, 56 % of analytes detected in biofilms were not found in water samples, indicating traditional pesticide monitoring practices fail to capture all exposure routes, as even when pesticides are below detection levels in water, organisms may still be exposed via dietary pathways. Calculated bioconcentration factors ranged from 4.2 to 1275 and were not predicted by standard pesticide physicochemical properties. Monitoring biofilms provides a sensitive and comprehensive supplement to water sampling for pesticide quantification in urban areas, and identifying pesticide occurrences in stormwater could improve source-tracking efforts in the future. Further research is needed to understand the mechanisms driving pesticide accumulation, to investigate toxicity risks associated with pesticide-contaminated biofilm, and to evaluate whether pesticide accumulation in stormwater pond biofilms represents a route through which contaminants are mobilized into the surrounding terrestrial and downstream aquatic environments.

Adsorption of azoxystrobin and pyraclostrobin onto degradable and non-degradable microplastics: Performance and mechanism

Microplastics (MPs) exist after agricultural operations and thus present potential hazards to the environment and human health. However, the ecological risks posed by MPs carrying pesticides remain unclear. In this study, the adsorption and desorption behaviors of two pesticides, azoxystrobin and pyraclostrobin, on degradable and non-degradable MPs of poly(butylene adipate-co-terephthalate) (PBAT) and polyethylene (PE) were compared before and after UV aging. Additionally, the bioaccessibility of MPs carrying pesticides within a condition simulating gastrointestinal fluids was evaluated. The results showed that, after UV aging, the adsorption capacity of PBAT for pesticides decreased, while that of PE increased. Moreover, PBAT possessed higher adsorption ability towards both the pesticides due to its higher specific surface area, pore volume, contact angle, and lower crystallinity, as well as stronger van der Waals forces, electrostatic interactions, and hydrogen bonding indicated by theoretical calculation. Bioaccessibility experiments showed that azoxystrobin and pyraclostrobin had a higher risk of desorption from PBAT than PE, which is mainly dependent on the LogKow of pesticides according to the random forest analysis. In brief, the study highlights the potential risks of degradable MPs carrying pesticides to human health and the ecosystem, especially when compared to their non-degradable counterparts, manifesting that the ecological risk posed by degradable MPs should not be ignored.

Uptake, Translocation, and Subcellular Distribution of Strobilurin Fungicides in Cucumber (Cucumis sativa L.)

The absorption, transport, and subcellular distribution of strobilurin fungicides (azoxystrobin, pyraclostrobin, and trifloxystrobin) have been studied in cucumbers. Under hydroponic laboratory conditions, pyraclostrobin and trifloxystrobin mainly accumulated in cucumber roots whereas azoxystrobin accumulated in cucumber leaves. In the subcellular distribution experiment, azoxystrobin mainly accumulated as a soluble component. Pyraclostrobin and trifloxystrobin accumulated more in the organelles and cell walls. Azoxystrobin and pyraclostrobin enter the root primarily through the apoplast pathway, whereas trifloxystrobin enters the root through the symplastic pathway. Azoxystrobin can be transported in cucumber through anion and cation channels, whereas pyraclostrobin and trifloxystrobin can be transported only through anion channels. This study has great significance in evaluating environmental risks and food safety.

Absorption, metabolism and distribution of carbosulfan in maize plants (Zea mays L.)

BACKGROUND

The insecticide carbosulfan is usually applied as a soil treatment or seed-coating agent, and so may be absorbed by crops and pose dietary risks. Understanding the uptake, metabolism and translocation of carbosulfan in crops is conducive to its safe application. In this study, we investigated the distribution of carbosulfan and its toxic metabolites in maize plants at both the tissue and subcellular levels, and explored the uptake and translocation mechanism of carbosulfan.

RESULTS

Carbosulfan was mainly taken up by maize roots via the apoplast pathway, was preferentially distributed in cell walls (51.2%-57.0%) and most (85.0%) accumulated in roots with only weak upward translocation. Carbofuran, the main metabolite of carbosulfan in maize plants, was primarily stored in roots. However, carbofuran could be upwardly translocated to shoots and leaves because of its greater distribution in root-soluble components (24.4%-28.5%) compared with carbosulfan (9.7%-14.5%). This resulted from its greater solubility compared with its parent compound. The metabolite 3-hydroxycarbofuran was found in shoots and leaves.

CONCLUSION

Carbosulfan could be passively absorbed by maize roots, mainly via the apoplastic pathway, and transformed into carbofuran and 3-hydroxycarbofuran. Although carbosulfan mostly accumulated in roots, its toxic metabolites carbofuran and 3-hydroxycarbofuran could be detected in shoots and leaves. This implies that there is a risk in the use of carbosulfan as a soil treatment or seed coating. © 2023 Society of Chemical Industry.

Diverse bacteria colonizing leaves and the rhizosphere of lettuce degrade azoxystrobin

Concerns about the possible effects of pesticide residues on both the environment and human health have increased worldwide. Bioremediation by the use of microorganisms to degrade or remove these residues has emerged as a powerful technology. However, the knowledge about the potential of different microorganisms for pesticide degradation is limited. This study focused on the isolation and characterisation of bacterial strains with the potential to degrade the active fungicide ingredient azoxystrobin. Potential degrading bacteria were tested in vitro and in the greenhouse, and the genomes of the best degrading strains were sequenced and analysed. We identified and characterised 59 unique bacterial strains, which were further tested in vitro and in greenhouse trials for their degradation activity. The best degraders from a foliar application trial in the greenhouse were identified as Bacillus subtilis strain MK101, Pseudomonas kermanshahensis strain MK113 and Rhodococcus fascians strain MK144 and analysed by whole genome sequencing. Genome analysis revealed that these three bacterial strains encode several genes predicted to be involved in the degradation of pesticides e.g., benC, pcaG, pcaH, however we could not find any specific gene previously reported to be involved in azoxystrobin degradation e.g., strH. Genome analysis pinpointed to some potential activities involved in plant growth promotion.

Enantioselective uptake, translocation, and biotransformation of pydiflumetofen in wheat (Triticum aestivum L.): Insights from chiral profiling and molecular simulation

Pydiflumetofen (PYD), a highly effective and broad-spectrum fungicide, is commonly employed for the control of fungal diseases. In this study, the uptake, translocation, and biotransformation of PYD by wheat (Triticum aestivum L.) were firstly investigated at a chiral level. The findings revealed that the residue concentration of R-PYD in wheat was higher than that of S-PYD, because of its higher uptake rate (k1 = 0.0421 h-1) and lower elimination rate (k2 = 0.0459 h-1). Additionally, R-PYD exhibited higher root bioconcentration factors and translocation factors compared with S-enantiomer, indicating R-PYD was more easily accumulating in roots and translocating to shoots. Furthermore, a total of 9 metabolites, including hydroxylated, demethylated, demethoxylated, dechlorinated, hydrolyzed, and glycosylated-conjugated products, were detected qualitatively in wheat roots or shoots. Symplastic pathway-mediated uptake, which predominantly relied on aquaporins and anion channels, was confirmed by root adsorption and inhibition experiments, without displaying any enantioselective effect. Molecular simulations demonstrated that R-PYD exhibited stronger binding affinity with TaLTP 1.1 with a lower grid score (-6.79 kcal/mol), whereas weaker interaction with the metabolic enzyme (CYP71C6v1) compared to the S-enantiomer. These findings highlight the significance of plant biomacromolecules in the enantioselective bioaccumulation and biotransformation processes. Importantly, a combination of experimental and theoretical evidence provide a comprehensive understanding of the fate of chiral pesticides in plants from an enantioselective perspective.

Dissipation patterns, residue analysis, and risk evaluation of hexaflumuron in turnip and cauliflower under Chinese growth conditions

Hexaflumuron has been globally registered over 2 decades to control the pests in brassicaceous vegetables, while data on its dissipation and residues in turnip and cauliflower is scarce. Herein, field trials were carried out at six representative experimental sites to study the dissipation behaviors and terminal residues of hexaflumuron in turnip and cauliflower. The residual amounts of hexaflumuron were extracted using a modified QuEChERS and analyzed with liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), the chronic dietary risk to Chinese populations was evaluated, and the maximum residue limit (MRL) in cauliflower, turnip tubers, and turnip leaves was calculated by the OECD MRL calculator. The single first-order kinetics model was the best-fitted kinetics model for hexaflumuron dissipation in cauliflower. The indeterminate order rate equation and first-order multi-compartment kinetic model were the best formulae for hexaflumuron dissipation in turnip leaves. The half-lives of hexaflumuron ranged from 0.686 to 1.35 and 2.41 to 6.71 days in cauliflower and turnip leaves, respectively. The terminal residues of hexaflumuron in turnip leaves of 0.321-9.59 mg/kg were much higher than in turnip tubers of < 0.01-0.708 mg/kg and cauliflower of < 0.01-1.49 mg/kg at sampling intervals of 0, 5, 7, and 10 days. The chronic dietary risk of hexaflumuron in the preharvest interval of 7 days was lower than 100% and much higher than 0.01%, indicating acceptable but nonnegligible health hazards for Chinese consumers. Therefore, MRL values of hexaflumuron were proposed as 2, 0.8, and 10 mg/kg in cauliflower, turnip tubers, and turnip leaves, respectively.

A powerful helper of azoxystrobin degradation-the unique mechanism of UGT72E2 promoting environmental degradation of azoxystrobin

In recent years, environmental pollutants such as pesticide residues have become one of the severe public problems that endanger the ecological environment and affect human health. The development of biotechnology to rapidly and efficiently degrade pesticides is essential to reduce their environmental risks. Azoxystrobin (AZ) is representative of the most widely used agricultural fungicide in the world. A large number of studies have shown that AZ has toxic effects on non-target organisms such as fish, algae, earthworms, etc., which may pose a potential threat to the environmental ecosystem. Therefore, it is particularly important to develop new AZ phytoremediation methods. Based on the constructed Arabidopsis UGT72E2 knockout (KO) and overexpression (OE) lines, this study found that overexpression of UGT72E2 in Arabidopsis can enhance resistance to exogenous AZ stress and maintain a relatively stable physiological state while enhancing the metabolic degradation of AZ. Correspondingly, knockout mutants showed the opposite results. The results showed that the AZ glycosylation and malonyl glycosylation products produced by UGT72E2 overexpression lines increased by 10%~20% compared with normal lines, and increased by 7%~47% compared with gene knockout plants, and exhibited lower phytotoxicity. In summary, our findings highlight the critical role of UGT72E2 overexpression in constructing new varieties of phytoremediation and may provide new ideas for reducing the indirect or direct risks of pesticides or other environmental pollutants to non-target organisms and improving biological and environmental resilience.

Biobased, Macro-, and Nanoscale Fungicide Delivery Approaches for Plant Fungi Control

In this report, two polymeric matrix systems at macro and nanoscales were prepared for efficacious fungicide delivery. The macroscale delivery systems used millimeter-scale, spherical beads composed of cellulose nanocrystals and poly(lactic acid). The nanoscale delivery system involved micelle-type nanoparticles, composed of methoxylated sucrose soyate polyols. Sclerotinia sclerotiorum (Lib.), a destructive fungus affecting high-value industrial crops, was used as a model pathogen against which the efficacy of these polymeric formulations was demonstrated. Commercial fungicides are applied on plants frequently to overcome the transmission of fungal infection. However, fungicides alone do not persist on the plants for a prolonged period due to environmental factors such as rain and airflow. There is a need to apply fungicides multiple times. As such, standard application practices generate a significant environmental footprint due to fungicide accumulation in soil and runoff in surface water. Thus, approaches are needed that can either increase the efficacy of commercially active fungicides or prolong their residence time on plants for sustained antifungal coverage. Using azoxystrobin (AZ) as a model fungicide and canola as a model crop host, we hypothesized that the AZ-loaded macroscale beads, when placed in contact with plants, will act as a depot to release the fungicide at a controlled rate to protect plants against fungal infection. The nanoparticle-based fungicide delivery approach, on the other hand, can be realized via spray or foliar applications. The release rate of AZ from macro- and nanoscale systems was evaluated and analyzed using different kinetic models to understand the mechanism of AZ delivery. We observed that, for macroscopic beads, porosity, tortuosity, and surface roughness governed the efficiency of AZ delivery, and for nanoparticles, contact angle and surface adhesion energy were directing the efficacy of the encapsulated fungicide. The technology reported here can also be translated to a wide variety of industrial crops for fungal protection. The strength of this study is the possibility of using completely plant-derived, biodegradable/compostable additive materials for controlled agrochemical delivery formulations, which will contribute to reducing the frequency of fungicide applications and the potential accumulation of formulation components in soil and water.

New Insights into the Accumulation, Transport, and Distribution Mechanisms of Hexafluoropropylene Oxide Homologues, Important Alternatives to Perfluorooctanoic Acid, in Lettuce (Lactuca sativa L.)

Hexafluoropropylene oxide (HFPO) homologues, which are important alternatives to perfluorooctanoic acid, have been frequently identified in crops. Although exposure to HFPO homologues via crops may pose non-negligible threats to humans, their impact on crops is still unknown. In this study, the accumulation, transport, and distribution mechanisms of three HFPO homologues in lettuce were investigated at the plant, tissue, and cell levels. More specifically, HFPO trimer acid and HFPO tetramer acid were primarily fixed in roots and hardly transported to shoots (TF, 0.06-0.63). Conversely, HFPO dimer acid (HFPO-DA) tended to accumulate in lettuce shoots 2-264 times more than the other two homologues, thus resulting in higher estimated daily intake values. Furthermore, the dissolved organic matter derived from root exudate enhanced HFPO-DA uptake by increasing its desorption fractions in the rhizosphere. The transmembrane uptake of HFPO homologues was controlled by means of a transporter-mediated active process involving anion channels, with the uptake of HFPO-DA being additionally facilitated by aquaporins. The higher accumulation of HFPO-DA in shoots was attributed to the larger proportions of HFPO-DA in the soluble fraction (55-74%) and its higher abundance in both vascular tissues and xylem sap. Our findings expand the understanding of the fate of HFPO homologues in soil-crop systems and reveal the underlying mechanisms of the potential exposure risk to HFPO-DA.

Uptake and Biotransformation of Spirotetramat and Pymetrozine in Lettuce (Lactuca sativa L. var. ramosa Hort.)

Here, we investigated the uptake, transport, and subcellular distribution of the pesticides pymetrozine and spirotetramat, and spirotetramat metabolites B-enol, B-glu, B-mono, and B-keto, under hydroponic conditions. Spirotetramat and pymetrozine exhibited high bioconcentrations in lettuce roots, with both having root concentration factor (RCF) values >1 after exposure for 24 h. The translocation of pymetrozine from roots to shoots was higher than that of spirotetramat. Pymetrozine is absorbed in roots mainly via the symplastic pathway and is primarily stored in the soluble fraction of lettuce root and shoot cells. The cell wall and soluble fractions were the major enrichment sites of spirotetramat and its metabolites in root cells. Spirotetramat and B-enol were mainly enriched in the soluble fractions of lettuce shoot cells, whereas B-keto and B-glu accumulated in cell walls and organelles, respectively. Both symplastic and apoplastic pathways were involved in spirotetramat absorption. Pymetrozine and spirotetramat uptake by lettuce roots was passive, with no aquaporin-mediated dissimilation or diffusion. The findings of this study enhance our understanding of the transfer of pymetrozine, spirotetramat, and spirotetramat metabolites from the environment to lettuce, and their subsequent bioaccumulation. This study describes a novel approach for the efficient management of lettuce pest control using spirotetramat and pymetrozine. At the same time, it is of great significance to evaluate the food safety and environmental risks of spirotetramat and its metabolites.

Uptake, translocation and metabolism of acetamiprid and cyromazine by cowpea (Vigna unguiculata L.)

Acetamiprid (ACE) and cyromazine (CYR) are the two pesticides that are used relatively frequently and in large quantities in cowpea growing areas in Hainan. The uptake, translocation and metabolic patterns and subcellular distribution of these two pesticides in cowpea are important factors affecting pesticide residues in cowpea and assessing the dietary safety of cowpea. In this study, we investigated the uptake, translocation, subcellular distribution, and metabolic pathway of ACE and CYR in cowpea under laboratory hydroponic conditions. The distribution trends of both ACE and CYR in cowpea plants were leaves > stems > roots. The distribution of both pesticides in subcellular tissues of cowpea was cell soluble fraction > cell wall > cell organelle, and both transport modes were passive. A multiplicity of metabolic reactions of both pesticides occurred in cowpea, including dealkylation, hydroxylation and methylation. The results of the dietary risk assessment indicate that ACE is safe for use in cowpeas, but CYR poses an acute dietary risk to infants and young children. This study provided a basis for insights into the transport and distribution of ACE and CYR in vegetables and contributes to the assessment of whether pesticide residues in vegetables could pose a potential threat to human health at high concentrations of pesticides in the environment.

Determination of Pesticide Residues in IV Range Artichoke (Cynara cardunculus L.) and Its Industrial Wastes

Fourth-range products are those types of fresh fruit and vegetables that are ready for raw consumption or after cooking, and belong to organic or integrated cultivations. These products are subject to mild post-harvesting processing procedures (selection, sorting, husking, cutting, and washing), and are afterwards packaged in packets or closed food plates, with an average shelf life of 5-10 days. Artichokes are stripped of the leaves, stems and outer bracts, and the remaining heads are washed with acidifying solutions. The A LC-MS/MS analytical method was developed and validated following SANTE guidelines for the detection of 220 pesticides. This work evaluated the distribution of pesticide residues among the fraction of artichokes obtained during the industrial processing, and the residues of their wastes left on the field were also investigated. The results showed quantifiable residues of one herbicide (pendimethalin) and four fungicides (azoxystrobin, propyzamide, tebuconazole, and pyraclostrobin). Pendimethalin was found in all samples, with the higher values in leaves 0.046 ± 8.2 mg/kg and in field waste 0.30 ± 6.7 mg/kg. Azoxystrobin was the most concentrated in the outer bracts (0.18 ± 2.9 mg/kg). The outer bracts showed the highest number of residues. The industrial waste showed a significant decrease in the number of residues and their concentration.

Uptake, Translocation, and Distribution of Cyantraniliprole in a Wheat Planting System

Cyantraniliprole uptake, translocation, and distribution in wheat plants grown in hydroponics and soil conditions were investigated. The hydroponics experiment indicated that cyantraniliprole was prone to be absorbed by wheat roots mainly through the apoplastic pathway and predominately distributed in the cell-soluble fraction (81.4-83.6%) and ultimately transferred upward to leaves (TF_leave/stem = 4.84 > TF_stem/root = 0.67). In wheat-soil systems, the uptake of cyantraniliprole was similar to that in hydroponics. The accumulation of cyantraniliprole in wheat tissues was mainly affected by the content of soil organic matter and clay, resulting in the increased adsorption of cyantraniliprole onto soils (R² > 0.991, P < 0.01), and was positively related to the concentration of cyantraniliprole in soil pore water (R² > 0.991, P < 0.001). Besides, the absorption of cyantraniliprole by wheat was predicted well by the partition-limited model. These results increased our understanding of the absorption and accumulation of cyantraniliprole in wheat and were also helpful for guiding the practical application and risk evaluation of cyantraniliprole.

Uptake kinetics and subcellular distribution of three classes of typical pesticides in rice plants

Food safety problems caused by pesticide residues have always been a concern for many people. In this study, we investigated the uptake, translocation and subcellular distribution of neonicotinoid insecticides, triazole fungicides, and sulfonylurea herbicides in rice plants (Oryza sativa L.). The time-dependent uptake kinetics of the three categories of pesticides with different molecular structures fit a first-order one-compartment kinetic model. The neonicotinoids (log K_ow -0.66-0.8) were mainly concentrated in the leaves, and the triazoles (log K_ow 3.72-4.4) were mainly concentrated in the roots. Neonicotinoid pesticides in the roots were preferentially transported across the membrane through the symplastic pathway; triazole pesticides except for triadimefon and myclobutanil preferentially passed through the symplastic pathway; and sulfonylurea pesticides (log K_ow 0.034-2.89) were first transported upward through the apoplastic pathway. In the roots, neonicotinoids, triazoles, and sulfonylurea herbicides were mainly concentrated in the soluble fractions, cell wall and apoplast fractions, respectively. In addition, there was a high positive correlation between the subcellular distribution of pesticides in the roots, stems and leaves. Molecular weight and log K_ow jointly affected the enrichment of triazole pesticides in the roots, stems and leaves and the transfer from stems to leaves, while water solubility and log K_ow commonly affected neonicotinoids. There was a correlation between pesticide absorption and the molecular structures of pesticides. To develop pesticides with strong uptake and transport capabilities, it is necessary to consider that the electronegativity of some atoms is stronger, the sum of the topological indices of heteroatoms can be large, and the van der Waals volume increases accordingly.

Uptake and translocation of fungicide picarbutrazox in greenhouse cabbage: the significance of translocation factors and home processing

This study evaluated the uptake and translocation of the fungicide picarbutrazox (PBZ) and its isomer in greenhouse cabbage. Two distinct treatments, including foliar spray and soil application of PBZ, were used in this study. In the foliar application, the fungicide was sprayed thrice at intervals of 7 days from 30, 21, and 14 days before harvest following the OECD guidelines of fungicides in crops, whereas in soil treatment, PBZ was applied for one time at concentrations of 2 and 10 mg/kg, and cabbage was cultivated for 68 days. Additionally, the role of root and translocation factors during residual fungicide distribution was demonstrated. The quality control of the analytical study exhibited excellent linearity (R² ≥ 0.99), the limit of quantification (LOQ 0.005 mg/kg), accuracy (recovery within the range of 70-120%), and precision (relative coefficient within 0.3-13.8%) for studied PBZ and its metabolites. In the foliar application, initially higher amount of residual PBZ was evident in the outermost leaf of the cabbage, whereas in soil treatment, the highest residual PBZ was observed in the soil and roots. Therefore, the application method of picarbutrazox is a critical factor for defining the initial entry route of pesticides and the subsequent translocations through the investigated crops.

Cytogenotoxic activity of herbicidal and fungicidal pesticides on Triticum aestivum root meristem

Phytotoxicity, cytotoxicity and genotoxicity of pesticides with various mechanisms of targeted activity were studied in a hydroponic culture of 2-day-old seedlings of Triticum aestivum. All studied pesticides (with the exception of metribuzin) exhibited dose-dependent phytotoxicity (inhibited the growth of the main root and reduced the yield of root biomass). All studied pesticides did not affect mitotic index in the root apex meristem but did affect the duration of some phases of mitosis. Herbicides increased, while fungicides, on the contrary, decreased the duration of the cytokinesis phase. All pesticides (1 μg/mL) exhibited genotoxic activity: in the root apex meristem the number of cells with mitotic abnormalities was significantly higher than in the control variant (7-14 times). The genotoxic activity of metribuzin and tebuconazole was 2 times lower than for tribenuron-methyl, fenoxaprop-P-ethyl, epoxiconazole and azoxystrobin. The genotoxicity of the studied pesticides was combined: depending on the class of the pesticide, clastogenic or aneugenous effects dominated.

Uptake, Translocation, and Subcellular Distribution of Oxathiapiprolin and Famoxadone in Tomato Plants (Lycopersicon esculentum Miller)

The uptake, translocation, and subcellular distribution of oxathiapiprolin and famoxadone in tomato plants were investigated using hydroponic experiments. Oxathiapiprolin and famoxadone mainly accumulated in the tomato roots with limited translocation capacity from the roots to the upper part. The root absorption and inhibitor results noted the dominance of the apoplastic and symplastic pathways in the oxathiapiprolin and famoxadone uptake by the tomato roots, respectively. Furthermore, the uptake process for the two fungicides followed passive and aquaporin-dependent transport. Insoluble cell components (cell organelles and walls) were the dominant storage compartments for oxathiapiprolin and famoxadone. In the protoplast, oxathiapiprolin in the soluble fraction had a higher proportion than that of famoxadone. Finally, the uptake and distribution of the two fungicides by the tomato plants was accurately predicted using a partition-limited model. Thus, this study provides an in-depth understanding of the transfer of oxathiapiprolin and famoxadone from the environment to tomato plants.

Finding the Missing Property Concepts in Pesticide-Likeness

Poor bioavailability of pesticides is one of the major bottlenecks in the development of pesticides. Applications of the concept of pesticide-likeness have been widely accepted as one of the ways to break the bottleneck. At present, the evaluation of pesticide-likeness is mainly based on absorption, distribution, metabolism, excretion, and toxicity (ADME-T) property concepts of pesticides. However, a few significant property concepts of pesticides are ignored in the research of pesticide-likeness. Herein, we summarize the current study of ADME-T and other property concepts and analyze physicochemical properties for pesticides in the last 30 years, such as Fsp³, log P, and chiral centers. On the basis of these analyses, we propose that molecular complexity and residual property concepts of pesticides should be considered in the pesticide-likeness study. We hope that this work can help pesticide researchers and students, who are less knowledgeable in the field, to assess pesticide-likeness.

Uptake, translocation and distribution of cyantraniliprole in rice planting system

While cyantraniliprole has been frequently used in rice fields, knowledge of the uptake, translocation and distribution of cyantraniliprole in rice planting systems is still largely unexplored. Plant uptake is a crucial factor in determining how cyantraniliprole moves through the food chain. Understanding the uptake, translocation and distribution of cyantraniliprole in rice planting system is essential to predicting its accumulation in rice and potential human exposure. Herein, the uptake process of cyantraniliprole in a hydroponic-rice system was systematically investigated. Results showed that cyantraniliprole was easily absorbed by rice roots via a passive diffusion process through the apoplastic pathway and then translocated upward through the xylem, but its acropetal translocation was limited. Cyantraniliprole in shoots can also be downward translocated through the phloem, although only to a limited extent, showing rice plants' weak phloem movement capacity. Furthermore, cyantraniliprole had a short half-life in sediment-water system and dissipated faster in anaerobic than aerobic conditions. At the equilibrium stage of a sediment-water system, cyantraniliprole is preferentially partitioned to the solid phase. Our study provides a systematic insight into the uptake, translocation and distribution of cyantraniliprole in the rice planting system, which is very helpful for better field cyantraniliprole application and environmental risk assessment.

Uptake, translocation, and degradation of spirotetramat in tomato (Lycopersicon esculentum Miller): Impact of the mixed-application with pymetrozine

In this study, we investigated the impact of the mixed-application with pymetrozine on the behavior (i.e., uptake, translocation, and degradation) of spirotetramat in tomatoes under laboratory conditions. Results showed that pymetrozine promoted the uptake of spirotetramat from the nutrition solution after root application. The root concentration factor was 0.290 and 1.566 after spirotetramat single application and mixed-application with pymetrozine, respectively. It had little effect on the degradation of spirotetramat, with the metabolites of M-keto, M-enol, and M-glu in tomato issue (root, stems, and leaves). After foliar treatments, pymetrozine accelerated the translocation of spirotetramat from leaves to stems, with the translocation factor of 0.145 and 0.402 after spirotetramat single application and mixtures with pymetrozine, respectively. Pymetrozine also promoted the degradation of spirotetramat to M-kto and M-enol in leaves. Besides, a partition-limited model was used to describe the distribution processes of spirotetramat in the tomato-water system after root application. It showed that pymetrozine accelerated the distribution balance of spirotetramat in the whole system. Our result indicates that the interaction among pesticides should be considered when studied for the uptake, translocation, and degradation of pesticides in crops.

Uptake, Accumulation, and translocation of azoxystrobin by Vegetable plants in soils: influence of soil characteristics and plant species

Although azoxystrobin has been widely applied on various crops, little is known about the bioavailability of azoxystrobin in the soil-vegetable system. In this study, the uptake, accumulation and translocation of azoxystrobin as affected by soil characteristics and plant species were respectively investigated. The accumulation amount of azoxystrobin in pakchoi increased as soil adsorption decreased and was positively associated with its concentration in pore water (C_pw), which was mainly affected by soil organic matter content. Therefore, C_pw could be a candidate for the estimation of azoxystrobin accumulation in pakchoi. In all the tested vegetables, azoxystrobin was mainly accumulated in roots, and its upward translocation was limited. Root lipid content was a major factor affecting the uptake and translocation of azoxystrobin in different vegetables.

Insight into the uptake, accumulation, and metabolism of the fungicide phenamacril in lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.)

The fungal species Fusarium can cause devastating disease in agricultural crops. Phenamacril is an extremely specific cyanoacrylate fungicide and a strobilurine analog that has excellent efficacy against Fusarium. To date, information on the mechanisms involved in the uptake, accumulation, and metabolism of phenamacril in plants is scarce. In this study, lettuce and radish were chosen as model plants for a comparative analysis of the absorption, accumulation, and metabolic characteristics of phenamacril from a polluted environment. We determined the total amount of phenamacril in the plant-water system by measuring the concentrations in the solution and plant tissues at frequent intervals over the exposure period. Phenamacril was readily taken up by the plant roots with average root concentration factor ranges of 60.8-172.7 and 16.4-26.9 mL/g for lettuce and radish, respectively. However, it showed limited root-to-shoot translocation. The lettuce roots had a 2.8-12.4-fold higher phenamacril content than the shoots; whereas the radish plants demonstrated the opposite, with the shoots having 1.5 to 10.0 times more phenamacril than the roots. By the end of the exposure period, the mass losses from the plant-water systems reached 72.0% and 66.3% for phenamacril in lettuce and radish, respectively, suggesting evidence of phenamacril biotransformation. Further analysis confirmed that phenamacril was metabolized via hydroxylation, hydrolysis of esters, demethylation, and desaturation reactions, and formed multiple transformation products. This study furthers our understanding of the fate of phenamacril when it passes from the environment to plants and provides an important reference for its scientific use and risk assessment.

Dissipation and dietary exposure risk assessment of pyraclostrobin, fluxapyroxad, difenoconazole, and azoxystrobin in the Fritillaria field ecosystem

Fritillaria (Beimu in Chinese) is a well-known traditional Chinese medicinal herbal and valuable health food, which has attracted more and more attention. In this study, an efficient method was developed to determine pyraclostrobin, fluxapyroxad, difenoconazole, and azoxystrobin in plants, fresh Fritillaria, dry Fritillaria, and soil via liquid chromatography-tandem mass spectrometry. The average recoveries of the method were 78.9-109.7% with relative standard deviations of 0.94-11.1%. The dissipation half-lives of the four fungicides were 4.4-7.7 days in the Fritillaria plant and 11.6-18.2 days in the soil. The terminal residues of four fungicides were 0.033-0.13 mg/kg in fresh Fritillaria, 0.096-0.42 mg/kg in dry Fritillaria, and 0.12-0.74 mg/kg in soil. In the risk assessment of dietary exposure, all the chronic hazard quotient and acute hazard quotient index values were far below 100%, which were both acceptable to consumers. Accordingly, 7 days was recommended as the pre-harvest interval for the four fungicides in Fritillaria. This work could guide the safe use of these fungicides in Fritillaria and also give a reference for the Chinese government to establish the maximum residue limits (MRLs).

Uptake and translocation of triadimefon by wheat (Triticum aestivum L.) grown in hydroponics and soil conditions

Residual pesticides in soil may be taken in by plants and thus have a risk for plant growth and food safety. In this study, uptake of triadimefon and its subsequent translocation and accumulation were investigated with wheat as model plants. The results from hydroponics indicated that triadimefon was absorbed by wheat roots mainly through apoplastic pathway and predominantly distributed into the water soluble fractions (66.7-76.0%). After being uptaken by roots, triadimefon was easily translocated upward to wheat shoots and leaves. Interestingly, triadimefon in leaves was mainly distributed in the soluble fraction by 52.5% at the beginning, and gradually transferred into the cell wall by 47.2% at equilibrium. The uptake of triadimefon from soils by wheat plants was similar to that in hydroponics. Its accumulation were mainly governed by adsorption of the fungicide onto soils, and positively correlated with its concentration in in situ pore water (C_IPW). Thus, C_IPW can be suitable for predicting the uptake of triadimefon by wheat from soils. Accordingly, uptake of triadimefon by wheat was predicted well by using the partition-limited model. Our study provides valuable information for guiding the practical application and safety evaluation of triadimefon.

Fate, modeling, and human health risk of organic contaminants present in tomato plants irrigated with reclaimed water under real-world field conditions

Using reclaimed water to irrigate crops can be an important route for organic contaminants of emerging concern (CECs) to be introduced into agricultural production and thus find their way into the food chain. This work aims to establish accumulation models for the different parts of a crop (fruit/leaves/roots) and the soil of some of the most commonly detected CECs in reclaimed water, through field trials in greenhouses. For this, tomato plants were permanently irrigated under realistic agricultural conditions with a mixture of the selected compounds at approx. 1 μg/L. A total of 30 contaminants were analyzed belonging to different compound categories. A modified QuEChERS extraction method followed by liquid chromatography coupled to tandem mass spectrometry was the procedure used. The study revealed the presence of 21 target contaminants in the tomatoes, and 18 CECs in the leaves, roots, and soil. The average total concentration of pesticides detected in the tomatoes was 3 μg/kg f.w., whereas the average total load of pharmaceuticals was 5.8 μg/kg f.w. after three months, at the time of crop harvesting. The levels of pharmaceutical products and pesticides in the non-edible tissues were up to 3.5 and 2.1 μg/kg f.w., respectively, in the leaves and up to 89.3 and 31.3 μg/kg f.w., respectively, in the roots. In the case of the soil samples, the pesticide concentration found after crop harvesting was below 11.4 μg/kg d.w., and less than 3.0 μg/kg d.w. for pharmaceuticals. Overall, the concentration levels of CECs detected in the tomatoes, which were permanently irrigated with contaminated reclaimed water, do not pose a risk to human health via dietary intake.

Translocation versus ion trapping in the root uptake of 2,4-dichlorophenol by wheat seedlings

Understanding of the plant uptake of ionizable organic compounds is critical to the evaluation of crop contamination, plant protection, and phytoremediation. This study investigated the time-dependent uptake of 2,4-dichlorophenol (DCP) by intact wheat seedling roots and subsequent translocation to shoots at pH 5.0 and 8.0. Sorption of DCP by cut roots and shoots at these two pHs was conducted to provide the uptake limits and the Donnan charge. For comparison, sorption was also conducted for 1,3-dichlorobenzene (DCB), a nonionizable compound having a structure similar to that of DCP. The DCB sorption isotherms were linear and independent of pH, yielding a consistent log K_lip of 3.56 with both roots and shoots, reflective of the essential dominant role of lipids in plant partition uptake. Whereas the DCP sorption also showed a linear isotherm at pH 5.0 with log K_lip = 2.88, the sorption at pH 8.0 was nonlinear with a concave downward shape, especially at low concentrations. With live wheat seedlings, the DCB uptake by roots and the DCB translocation to shoots rapidly approached a steady state, showing no obvious pH effect. On the DCP uptake by live plants, there was a rapid attainment of a steady state in roots at pH 5.0 coupled with a retarded transport to shoots due presumably to the polarity of DCP. At pH 8.0, the root uptake of DCP was comparatively slower and the translocation to shoots was completely inhibited due presumably to DCP ionization. At high pH, DCP was supposedly accumulated in an ionized form in root cells via an ion-trapping mechanism.

Uptake, subcellular distribution and metabolism of 14C-caffeine in leafy vegetables from water

Irrigation with treated wastewater could lead to the accumulation of caffeine in agricultural fresh. Caffeine is one of the most frequently detected compounds in treated wastewater; however, little is known about its subcellular distribution and metabolism in vegetables. This study reported the uptake, subcellular distribution, and metabolism of ¹⁴C-caffeine in Chinese flowering cabbage and water spinach. The results showed that 98% of caffeine lost from solution after 768 h of cultivation. Caffeine was taken up by vegetables and most ¹⁴C-activity was accumulated in the bottom leaves. At the subcellular level, ¹⁴C-activity was mainly distributed in the organelles in root and stem cells, while in the leafy cells it was dominant in the solution. The metabolism of caffeine was investigated using LC-QTOF-MS. Caffeine underwent demethylation forming xanthine and theobromine, and mineralization to release CO₂. Approximately 40.2% of the initially applied caffeine was accumulated in Chinese flowering cabbage as the parent compound (28.3%) and metabolites (11.9%), and 50.9% of the added caffeine was mineralized to CO₂ after 768 h of exposure. The knowledge obtained herein is key to evaluating potential risks of caffeine present in treated wastewater, and the quality and safety of agricultural fresh produced by irrigation with treated wastewater.

Photostable 1-Trifluoromethyl Cinnamyl Alcohol Derivatives Designed as Potential Fungicides and Bactericides

In the current work, a series of 1-trifluoromethyl cinnamyl alcohol derivatives were designed and synthesized and their antifungal activities were evaluated. The bioassay result showed that most compounds exhibited excellent antifungal activity in vitro at 10 μg mL^-1. Next, photostable and easily synthesized compound 2 with broad-spectrum antifungal activity in vitro was selected as a potential candidate to evaluate its antibacterial and antifungal activities. The EC₅₀ values of compound 2 against eight fungal plant pathogens in vitro ranged from 3.806 to 17.981 μg mL^-1; at the same time, compound 2 could effectively control Podosphaera xanthii, Odium heveae Steinm, Puccinia striiformis West, and Puccinia sorghi in pot experiments. In addition, compound 2 exhibited excellent antibacterial activities in vitro and in vivo against Xanthomonas oryzae pv. oryzae. Furthermore, the absorption and translocation of compound 2 in wheat plants were determined by the high-performance liquid chromatography method. The result showed that compound 2 could be translocated acropetally as well as basipetally in wheat plants. Finally, it was found that compound 2 had no cross-resistance with carbendazim, azoxystrobin, and boscalid.

Translocation and residue of 14C-benzene kresoxim-methyl in mature cucumber (Cucumis sativus L.)

The broad application of strobilurin fungicide led to pathogen resistance, and toxic effects have been reported for several species. Benzene kresoxim-methyl (BKM) is a novel strobilurin fungicide mainly used to control the cucumber powdery mildew. However, information about the fate of BKM in agrofood systems and related human exposure is limited. In this study, greenhouse experiments were conducted to investigate the distribution, translocation, and residual of the 10% suspension concentrate (SC) commercial BKM formulations on mature cucumber plants using ¹⁴C tracer technology. After foliage and fruit application, 25.84% of the applied ¹⁴C-labeled BKM can be absorbed into mature cucumber plants at 21 days after treatment. The absorbed BKM transferred throughout the plant acropetally and basipetally, although over 81.13% of absorbed BKM remained in the labeled leaves. In the edible parts, 14.35% of the absorbed BKM remained in the pericarp of labeled fruits, only 0.027 mg kg^-1 accumulated in the sarcocarp. The concentration of BKM in newborn fruits was 0.005 mg kg^-1, indicating low dietary exposure. These findings develop a better understanding of the fate of BKM in the cucumber plants, provide guidance in the rational use of BKM and can be incorporated into food and environmental assessments of BKM.

Uptake, Translocation, and Biotransformation of Neonicotinoid Imidaclothiz in Hydroponic Vegetables: Implications for Potential Intake Risks

Imidaclothiz is a novel and systemic neonicotinoid pesticide with excellent insecticidal efficacy. However, knowledge of its uptake, translocation, and biotransformation within plants is still largely unknown, restricting work on its accurate and comprehensive risk assessment. Here, we systematically investigated the behavior of imidaclothiz in three plant-water systems via hydroponic experiments. The results showed that imidaclothiz was readily taken up by plant roots and translocated upward, resulting in relative enrichment in leaves. The recoveries of imidaclothiz in plant-water systems decreased with increasing exposure time, and approximately 31.8-45.6% mass loss was measured at the end of exposure. Ultimately, imidaclothiz yielded five products in celery leaves, three products in lettuce leaves, and two products in radish leaves. Multiple metabolic reactions including hydroxylation, hydrolysis of nitrate ester, and methylation occurred within plants. This is the first report on the fate of imidaclothiz within plants and suggests increasing concerns about the risk assessment of imidaclothiz.

Chemical factors affecting uptake and translocation of six pesticides in soil by maize (Zea mays L.)

Uptake of residual pesticides in a soil by a certain crop plant may be governed by their physicochemical properties. Uptake and translocation of pesticides (imidacloprid, acetamiprid, tricyclazole, azoxystrobin, tebuconazole and difenoconazole) with the octanol/water partition coefficient (log K_ow) ranging from 0.57 to 4.36 were investigated in soil with maize as a model plant. The results show that all tested pesticides in soil were uptaken by maize with accumulation amount of 27.73, 17.75, 18.96, 12.56, 10.66 and 2.13 μg for imidacloprid, acetamiprid, tricyclazole, azoxystrobin, tebuconazole and difenoconazole at 14 d, respectively. The accumulation amount was negatively correlated with adsorption coefficients and positively correlated with pesticide concentration in in situ pore water (C_IPW). Root bioconcentration factor varied widely from 0.61 for imidacloprid to 974.64 for difenoconazole was positively correlated with log K_ow and molecular weight but negatively with water solubility. Conversely, translocation factor varied from 0 for difenoconazole to 1.64 for imidacloprid was negatively correlated with log K_ow but positively with water solubility. It determined that uptake, accumulation and translocation of the pesticides in soil by maize are governed by their physicochemical properties, especially log K_ow. C_IPW is an appropriate candidate to evaluate the accumulation of pesticides in maize from soil.

Root Uptake of Imidacloprid and Propiconazole Is Affected by Root Composition and Soil Characteristics

Residual pesticides in soil may be taken up by crops and negatively affect food safety. The uptake mechanism of imidacloprid and propiconazole was studied using wheat roots. The factors affecting root uptake were also studied with different crops and in different soils. Imidacloprid and propiconazole were taken up by wheat roots mainly through the symplastic and apoplastic pathways, respectively. Root protein and lipid contents were the main factors affecting the uptake and accumulation of imidacloprid and propiconazole by different crop roots, respectively. The uptake of imidacloprid and propiconazole in soil by wheat plants was linearly correlated with their concentrations in soil pore water, which were governed by soil characteristics. These results are helpful for understanding and estimating crop uptake of residual pesticides in soils.

Field study on bioaccumulation and translocation of polybrominated diphenyl ethers in the sediment-plant system of a national nature reserve, North China

Polybrominated diphenyl ethers (PBDEs) are the ubiquitous contaminants in the coastal wetlands, with high persistence and toxicity. Environmental behaviors of PBDEs in sediment-plant system is a hot research area, where much uncertainties still occurred in field environment. In this study, the sediments and Suaeda heteroptera were synchronously collected to investigate the bioaccumulation and translocation of PBDEs in Liaohe coastal wetland. Mean concentrations of PBDEs in sediments, roots, stems and leaves were 8.37, 6.64, 2.42 and 1.40 ng/g d.w., respectively. Tissue-specific accumulation of PBDEs were detected in Suaeda heteroptera, with predominant accumulation in roots. Congener patterns of PBDEs were similar between sediments and roots, demonstrating root uptake as the key pathway of PBDE bioaccumulation. The proportions of lower brominated congeners increased from roots to leaves, implying the congener-specific translocation. Meanwhile, the lower brominated congeners exhibited higher sediment-tissue bioaccumulation (AFs) and translocation factors (TFs) compared to higher brominated congeners in Suaeda heteroptera, further verifying their preferential translocation. AFs and TFs of PBDEs were both not correlated with their log K_ow, which was inconsistent with those of laboratory studies, reflecting the complicated behaviors of PBDEs in field environment. This is the first comprehensive report on bioaccumulation and translocation of PBDEs within Suaeda heteroptera in Liaohe coastal wetland.

Comparative uptake, translocation and subcellular distribution of phthalate esters and their primary monoester metabolites in Chinese cabbage (Brassica rapa var. chinensis)

Phthalates esters (PAEs) are ubiquitous contaminants in terrestrial system and PAEs can be degraded to monoester metabolites (mPAEs) both in soil and plants, which have equal or even greater biological activity compared to their parent compounds. Until now, little is known about the comparative uptake and translocation of PAEs and mPAEs in plants. In the present study, the uptake and translocation of two commonly used plasticizers, di-n-butyl phthalate (DnBP) and di-(2-ethylhexyl) phthalate (DEHP), and the corresponding mPAEs, mono-n-butyl phthalate (MnBP) and mono-(2-ethylhexyl) phthalate (MEHP) by Chinese cabbage (Brassica rapa var. chinensis) were examined using hydroponic experiment. Significantly lower bioconcentration factors (BCFs) of mPAEs compared to the corresponding PAEs were observed. This is likely due to the great solubility and electrical repulsion from cell membrane to mPAE anions. Comparatively low translocation factors (TFs) of MnBP (7.76 ± 0.49) were observed compared to DnBP (10.33 ± 2.83); while the TFs of MEHP (0.18 ± 0.08) were significantly greater than that of DEHP (0.05 ± 0.02). The hydrophilic mPAEs are prone to concentrate in cell water-soluble components, and DnBP was relatively uniformly distributed in cell wall and cell water-soluble components; while the more hydrophobic DEHP was mainly associated with root cell wall. The formation of mPAEs occurred mainly in the above-ground tissues in the PAEs spiked treatment, and cell water-soluble compartment was the main location for PAEs metabolism. The high metabolite/parent ratios in Chinese cabbage indicate that more concern should be directed towards metabolites associated with plants via direct uptake and plant metabolism.

Uptake mechanism, subcellular distribution, and uptake process of perfluorooctanoic acid and perfluorooctane sulfonic acid by wetland plant Alisma orientale

Perfluoroalkyl substances (PFASs) are of particular environmental concern due to their environmental persistence and potential toxicity. Phytoremediation may be used to remove PFASs from wastewater. Here we investigated the uptake mechanism, subcellular distribution, and uptake process of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate acid (PFOS) in the wetland plant Alisma orientale by using a series of hydroponic experiments. Active uptake facilitated by water transporters and anion channels was involved in the uptake of PFASs by plant roots. PFOA and PFOS were mainly distributed in the water-soluble fraction (46.2-70.8%) and in cell walls (45.6-58.4%), respectively. The uptake process was proposed as follows: PFOS and PFOA were first distributed in the soluble fraction; a proportion of PFOS and PFOA were adsorbed gradually by the cell wall, and a proportion of PFOS and PFOA in the cell wall passed through the cell wall and plasmalemma and bind with organelles. PFOS and PFOA were transported from the external solution to the vascular bundle of the plant root through both symplastic and apoplastic routes.

Uptake and Translocation of Triflumezopyrim in Rice Plants

A new type of mesoionic insecticide triflumezopyrim is mainly used to control rice planthoppers, leafhoppers, etc. In order to study the uptake and translocation characteristics of this new insecticide in rice (Oryza sativa), a method for the detection of triflumezopyrim in rice, soil, and water was established using liquid-liquid extraction and QuEChERS sample pretreatment combined with liquid chromatography-triple quadrupole tandem mass spectrometry. The distribution of triflumezopyrim in rice was investigated after hydroponic treatment and foliar treatment at the concentrations of 2.5 and 5 mg·L^-1 within the ranges of 24, 48, and 72 h. The results showed that triflumezopyrim could be absorbed by roots and form a systematic distribution in rice by hydroponic treatment; meanwhile, it could also be absorbed by leaves and transported to the bottom leaves under foliar treatment, but no triflumezopyrim was detected in the roots. Thus, triflumezopyrim exhibited high acropetal translocation within the rice plant. This study provides an important scientific basis for the development of an application strategy of triflumezopyrim to control planthoppers and leafhoppers as well as for the residue detection method and safety evaluation.

Subcellular distribution governing accumulation and translocation of pesticides in wheat (Triticum aestivum L.)

Root uptake, translocation, and subcellular distribution of six pesticides (dinotefuran, thiamethoxam, imidacloprid, imazethapyr, propiconazole, and chlorpyrifos) with K_ow ranging from -0.549 to 4.7 were investigated in wheat to study transportation and accumulation of pesticides. The root bioconcentration factor (RCF) of pesticides decreased with water solubility (R² = 0.6121) and increased with hydrophobicity (when the pH-adjusted log K_ow > 2, R² = 0.925), respectively. The translocation of neutral pesticides from roots to shoots increased positively with water solubility (R² > 0.6484) but decreased with hydrophobicity (R² > 0.8039). The subcellular fraction concentration factor (SFCF) increased linearly with hydrophobicity of the tested pesticides (R² > 0.958). The log RCF was positively correlated with log SFCF in root cell walls (R² = 0.9894) and organelles (R² = 0.9786). Transportation of the pesticides from roots to stems and stems to leaves was adversely affected by the log SFCF of cell walls and organelles of roots (R² > 0.7997) and stems (R² > 0.6666), respectively. Hydrophobicity-dependent SFCF is a factor governing accumulation of pesticides in roots after uptake and their subsequent upward translocation.

Upward translocation of acetochlor and atrazine in wheat plants depends on their distribution in roots

Residual acetochlor and atrazine in soils, resulting from their extensive application to maize plants, may affect product safety of the ultimate wheat crop. To determine the potential uptake and accumulation of acetochlor and atrazine by wheat plants, the uptake mechanism, translocation, and subcellular distribution of these two herbicides were studied through hydroponic experiments (10 mg L^-1). The results indicated that acetochlor can be taken up through the apoplastic pathway and can accumulate in wheat roots with little upward translocation. However, atrazine could be taken up by roots through the symplastic pathway and subsequently transported to the stems and leaves. Little upward translocation of acetochlor in wheat plants was due to its preferential distribution into root organelles with higher lipid contents. Conversely, the low bioconcentration of atrazine in root organelles and cell walls after uptake led to its easy upward translocation. Uptake of acetochlor and atrazine by wheat roots and the distribution of atrazine to the stems and leaves were predicted well by using the partition-limited model. The obtained results indicated that residual atrazine in soil may be taken up by wheat roots and acropetally translocated, thereby posing a threat to product safety of wheat.