Nano-selenium repaired the damage caused by fungicides on strawberry flavor quality and antioxidant capacity by regulating ABA biosynthesis and ripening-related transcription factors.

Recently, studies have shown that pesticides may have adverse effects on the flavor quality of the fruits, but there is still a lack of appropriate methods to repair the damage. This study investigated the effects and mechanism of applying the emerging material, nano­selenium, and two fungicides (Boscalid and Pydiflumetofen) alone or together on the flavor quality and antioxidant capacity of strawberries. The results showed that the two fungicides had a negative impact on strawberry color, flavor, antioxidant capacity and different enzymatic systems. The color damage was mainly attributed to the impact on anthocyanin content. Nano­selenium alleviated the quality losses by increasing sugar-acid ratio, volatiles, anthocyanin levels, enzyme activities and DPPH scavenging ability and reducing ROS levels. Results also showed that these damage and repair processes were related to the regulation of flavor and ripening related transcription factors (including FaRIF, FaSnRK1, FaMYB10, FaMYB1, FaSnRK2.6 and FaABI1), the upregulation of genes on sugar-acid, volatile, and anthocyanin synthesis pathways, as well as the increase of sucrose and ABA signaling molecules. In addition, the application of nano-Se supplemented the selenium content in fruits, and was harmless to human health. This information is crucial for revealing the mechanisms of flavor damage caused by pesticides to strawberry and the repaired of nano­selenium, and broadens the researching and applying of nano­selenium in repairing the damage caused by pesticides.

Nano-selenium foliar intervention-induced resistance of cucumber to Botrytis cinerea by activating jasmonic acid biosynthesis and regulating phenolic acid and cucurbitacin.

PURPOSE AND METHODS: Botrytis cinerea is the primary disease affecting cucumber production. It can be managed by applying pesticides and cultivating disease-resistant cucumber strains. However, challenges, such as drug resistance in pathogenic bacteria and changes in physiological strains, are obstacles in the effective management of B. cinerea. Nano-selenium (Nano-Se) has potential in enhancing crop resistance to biological stress, but the exact mechanism for boosting disease resistance remains unclear. Here, we used metabolomics and transcriptomics to examine how Nano-Se, as an immune activator, induces plant resistance. RESULT: Compared with the control group, the application of 10.0 mg/L Nano-Se on the cucumber plant's leaf surface resulted in increased levels of chlorophyll, catalase (10.2%), glutathione (326.6%), glutathione peroxidase (52.2%), cucurbitacin (41.40%), and metabolites associated with the phenylpropane synthesis pathway, as well as the total antioxidant capacity (21.3%). Additionally, the expression levels of jasmonic acid (14.8 times) and related synthetic genes, namely LOX (264.1%), LOX4 (224.1%), and AOC2 (309.2%), were up-regulated. A transcription analysis revealed that the CsaV3_4G002860 gene was up-regulated in the KEGG enrichment pathway in response to B. cinerea infection following the 10.0 mg/L Nano-Se treatment. DISCUSSION: In conclusion, the activation of the phenylpropane biosynthesis and branched-chain fatty acid pathways by Nano-Se promotes the accumulation of jasmonic acid and cucurbitacin in cucumber plants. This enhancement enables the plants to exhibit resistance against B. cinerea infections. Additionally, this study identified a potential candidate gene for cucumber resistance to B. cinerea induced by Nano-Se, thereby laying a theoretical foundation for further research in this area. © 2023 Society of Chemical Industry.

Improving red pitaya fruit quality by nano-selenium biofortification to enhance phenylpropanoid and betalain biosynthesis.

Red pitaya, the representative tropical and subtropical fruit, is vulnerable to quality deterioration due to climate or agronomic measures. Nano-selenium (Nano-Se) has shown positive effects on crop biofortification in favour of reversing this situation. In this study, Se could be enriched efficiently in red pitayas via root and foliar application by Nano-Se, which induced higher phenolic acids (16.9-94.2%), total phenols (15.7%), total flavonoids (29.5%) and betacyanins (34.1%) accumulation in flesh. Richer antioxidative features including activities of SOD (25.2%), CAT (33.8%), POD (77.2%), and levels of AsA (25.7%) and DPPH (14.7%) were obtained in Nano-Se-treated pitayas as well as in their 4-8 days shelf-life. The non-targeted metabolomics indicated a boost in amino acids, resulting in the stimulation of phenylpropanoid and betalain biosynthesis. In conclusion, the mechanism of Nano-Se biofortification for red pitaya might be fortifying pigment, as well as the enzymatic and non-enzymatic antioxidant substances formation by regulating primary and secondary metabolism facilitated by Se accumulation.

Nano-selenium enhances melon resistance to Podosphaera xanthii by enhancing the antioxidant capacity and promoting alterations in the polyamine, phenylpropanoid and hormone signaling pathways.

Powdery mildew is one of the main problematic diseases in melon production, requiring the use of chemical pesticides with disease-resistant cultivars for control. However, the often rapid acquisition of fungicidal resistance by mildew pathogens makes this practice unsustainable. The identification of crop treatments that can enhance resistance to powdery mildew resistance is therefore important to reduce melon crop attrition. This study indicates that the application of Nano-Se can reduce the powdery mildew disease index by 21-45%. The Nano-Se treatment reduced reactive oxygen species (ROS) and malondialdehyde (MDA) accumulation, with increases in glutathione (GSH), proline and 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH). Increases were also observed in the activities and transcriptional levels of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD). Assays with four different cultivars of melon with differing levels of mildew resistance demonstrated that relative to the control, the Nano-Se treatment resulted in larger responses to mildew infection, including increases in the levels of putrescine (PUT; 43-112%) and spermine (SPM; 36-118%), indoleacetic acid (IAA; 43-172%) and salicylic acid (SA; 24-73%), the activities of phenylalanine ammonium lyase (PAL), trans-cinnamate 4-hydroxylase (C4H) and 4-coumarate: Co A ligase (4CL) of the phenylpropanoid pathway (22-38%, 24-126% and 19-64%, respectively). Key genes in the polyamine and phenylpropanoid pathway were also upregulated. These results indicate that the foliar application of Nano-Se improved melon defenses against powdery mildew infection, with a significant reduction in mildew disease development.

Integration of metabolomics and transcriptomics analyses reveals the mechanism of nano-selenium treated to activate phenylpropanoid metabolism and enhance the antioxidant activity of peach.

Foliar spraying to improve the quality of fruits is a general approach nowadays. In this study, 10 ppm nano-selenium (nano-Se) diluted with distilled water was sprayed on peach leaves every 10 days for a total of 7 sprays during the fruit set period. And then their fruit quality was compared with that of control group. It was found that the firmness, soluble solid concentration, total phenol, and proanthocyanidin content of the peaches were raised after the nano-Se treatment. Moreover, the ascorbic acid glutathione loop (ASA-GSH loop) was fully activated in the nano-Se treated group, and the associated antioxidant capacity and enzyme activity were significantly increased. Metabolomics revealed that nano-Se could upregulate some metabolites, such as phenylalanine, naringenin, and pinocembrin, to fully activate the metabolism of phenylpropanoids. Further, based on transcriptomics, nano-Se treatment was found to affect fruit quality by regulating genes related to phenylpropanoid metabolism, such as arogenate/prephenate dehydratase (ADT), genes related to abscisic acid metabolism such as (+)-abscisic acid 8'-hydroxylase (CYP707A), and some transcription factors such as MYB. Based on the comprehensive analysis of physicochemical indicators, metabolomics, and transcriptomics, it was found that nano-Se improved fruit quality by activating phenylpropanoid metabolism and enhancing antioxidant capacity. This work provides insights into the mechanism of the effect of nano-Se fertilizer on peach fruit quality. PRACTICAL APPLICATION: The firmness and soluble solid concentration of peaches are higher after nano-Se treatment, which is more in line with people's demand for hard soluble peaches like "Yingzui." The antioxidant capacity, antioxidant substance content, and antioxidant enzyme activity of nano-Se-treated peaches are higher, with potential storage resistance and health effects on human body. The mechanism of nano-Se affecting peach quality was analyzed by metabolomics and transcriptomics, which is a reference and guide for the research and application of nano-Se.

Exogenous nanoselenium alleviates imidacloprid-induced oxidative stress toxicity by improving phenylpropanoid metabolism and antioxidant defense system in Perilla frutescens (L.) Britt.

Few studies have been conducted to investigate the impact of pesticides on the secondary metabolism of traditional Chinese medicine and strategies to mitigate the toxicity of pesticide-induced oxidative stress. The current study focuses on evaluating the potential impacts of nano selenium (NSe) and imidacloprid (IMI) on the quality, physiological biochemistry, and secondary metabolites in Perilla frutescens (L.) Britt. (P. frutescens). The study utilized metabolome analysis to explore the toxicity mechanism of IMI. The study noted that IMI-induced stress could emerge with detrimental effects by targeting the destruction of the phenylpropanoid biosynthesis pathway. IMI-induced phenylpropanoid metabolism disorder resulted in an 8%, 17%, 25%, 10%, 65%, and 29% reduction in phenylalanine, coniferyl aldehyde, ferulic acid, cafestol, p-coumaraldehyde, and p-coumaric acid levels, respectively. Under the treatment of exogenous NSe, the levels of these metabolites were increased by 16%, 32%, 22%, 22%, 92%, and 29%, respectively. The application of exogenous NSe increased the levels of these metabolites and improved the biochemical disorder and quality of P. frutescens leaves by optimizing the phenylpropanoid metabolic pathway and enhancing the antioxidant system. Overall, the results suggest that foliar application of NSe could alleviate the oxidative stress toxicity induced by IMI and improve the quality of P. frutescens.

Combined Application of Tank-mix Adjuvants, Mist Sprayer and Nano-selenium Promoted Pesticide Reduction and Enhanced Strawberry Quality.

In this paper, several technologies suitable for strawberry crops, such as armyworm boards, tank-mix adjuvants, mist sprayers combined with pesticide reduction, and biostimulant nano-selenium, were comprehensively applied and evaluated. The combined use of 60% etoxazole and bifenazate, bucket mixing additives, nano-selenium, and mist sprayers achieved an 86% prevention effect on red spiders. The prevention effect of pesticides according to the recommended dosage was 91%. Similarly, the disease index of strawberry powdery mildew in the green control group (60% carbendazim, bucket mixing additives, nano-selenium, and mist sprayer) decreased from 33.16 to 11.11, with a decrease of 22.05. The disease index of the control group decreased from 29.69 to 8.06, with a decrease of 21.63. Additionally, the combination of pesticide reduction and nano-selenium significantly improved the antioxidant activity and soluble sugar level of strawberry fruit and reduced water loss during storage. Therefore, the integrated application of green control technologies is beneficial for reducing the amount of chemical pesticides and improving their effectiveness, while enhancing the quality of strawberry fruits in disease and pest control.

Integrated non-targeted and targeted metabolomics analysis reveals the mechanism of inhibiting lignification and optimizing the quality of pea sprouts by combined application of nano-selenium and lentinans.

BACKGROUND: Lignification causes a detrimental impact on the quality of edible sprouts. However, the mechanism of inhibition of lignification of edible sprouts by nano-selenium and lentinans remains unclear. RESULTS: To reveal the mechanism of lignification regulation of sprouts by nano-selenium and lentinans, this study investigated the changes in antioxidant indicators, phytohormones, polyphenols, and metabolites in the lignin biosynthesis in pea sprouts following sprays of nano-selenium or/and lentinans twice. There was an overall increase in the aforementioned indices following treatment. In particular, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans was more effective than their individual applications in enhancing peroxidase, catalase, DPPH free-radical scavenging rate, luteolin, and sinapic acid, as well as inhibiting malondialdehyde generation and lignin accumulation. Combined with the results from correlation analysis, nano-selenium and lentinans may inhibit lignification by enhancing antioxidant systems, inducing phytohormone-mediated signaling, and enriching precursor metabolites (caffeyl alcohol, sinapyl alcohol, 4-coumaryl alcohol). In terms of the results of non-targeted metabolomics, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans mainly affected biosynthesis of plant secondary metabolites, biosynthesis of phenylpropanoids, phenylpropanoid biosynthesis, arginine and proline metabolism, and linoleic acid metabolism pathways, which supported and complemented results from targeted screenings. CONCLUSION: Overall, the combined sprays of nano-selenium and lentinans showed synergistic effects in delaying lignification and optimizing the quality of pea sprouts. This study provides a novel and practicable technology for delaying lignification in the cultivation of edible sprouts. © 2023 Society of Chemical Industry.

A novel perspective to investigate how nanoselenium and melatonin lengthen the cut carnation vase shelf.

Nano-selenium (nano-Se) and melatonin (MT) applications confirmed to boost plant growth and resistance. The mechanism of various ratios of nano-Se and MT foliar application postpone the senescence of fresh cut carnation flowers and improve vase life remains unclear. In this study, a combined effect with nano-Se (nano-Se5, 5 mg/L) and MT(MT1, 1 mg/L) was preferable to the control, nano-Se, and MT treatment alone when it came to delaying flower senescence. They enhance the antioxidant ability of carnation flowers by lowering MDA and H2O2 levels, raising SOD and POD concentrations, and lowering procyanidins biosynthesis (catechins and epicatechin). Inducing the biosynthesis of hormonal compounds (salicylic acid, jasmonic acid, and abscisic acid), their combination also boosted the growth of carnations. Biofortification with nano-Se and MT substantially increased the amounts of key lignin biosynthesis pathway metabolites (L-phenylalanine, p-hydroxycinnamic acid, p-coumaric acid, perillyl alcohol, p-Coumaryl alcohol, and cinnamic acid), which may increase stem cellular thickness and facilitate water absorption and transmission. The study hypothesizes that nano-Se and MT synergistic applications act as a new efficient non-toxic preservative to extend the vase life and improve the decorative value of carnations.

Nano-selenium enhances sugarcane resistance to Xanthomonas albilineans infection and improvement of juice quality.

Selenium is an important trace element that is beneficial to human health and can enhance plant resistance and crop quality. The occurrence of up-to-date nanotechnology greatly promotes the beneficial efficiency of this trace element on crops. The discovery of nano-Se increased the crop quality and reduced plant disease in different plant. In this study, we reduced sugarcane leaf scald disease incidence by exogenously spraying different concentrations (5 mg/L and 10 mg/L) of nano-Se. Additional studies revealed that spraying of nano-Se reduced reactive oxygen species (ROS) and H2O2 accumulation, and increased antioxidant enzyme activities in sugarcane. The nano-selenium treatments also increased the content of jasmonic acid (JA) and the expression of JA pathway genes. Furthermore, we also found that use nano-Se treatment in an appropriate way can enhance the quality of cane juice. The brix of the cane juice of the selenium-enriched treatment was significantly higher than that of the control group, which was 10.98% and 20.81% higher than that of the CK group, respectively. Meanwhile, the content of certain beneficial amino acids was increased, with the highest being 3.9 times higher than the control. Taken together, our findings inferred that nano-Se could act as a potential eco-fungicide to protect sugarcane from can be used as a potential ecological bactericide to protect sugarcane from Xanthomonas albilineans infections, and improve sugarcane quality. The results arising from this study not only introduces an ecological method to control X. albilineans, but also provides a deep insight into this trace elements for improving juice quality.

Determination of Multi-pesticides Residues in Jasmine Flower and Its Scented Tea.

For minor crops such as jasmine, the lack of pesticide registration and maximum residue limits are important issues that need to be solved in order to facilitate trading and ensure food safety. Meanwhile, reliable and quick analytical methods for multi-pesticide residues in these commodities are few, but required by various stakeholders. In this study, a method for detecting twenty-five most frequently used pesticides in jasmine flower and its scented tea by multi-plug filtration cleanup and ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated. The cleanup process was optimized and compared with the dispersive solid phase extraction procedure. The method was validated, showing that except for methomyl, recoveries of twenty-five pesticides were 64%-108%, with relative standard deviations (n = 5) of 0.33%-10%. The method was successfully applied to detect pesticide residues in marketed samples. The results showed that some flower and tea samples contained a combination of different pesticide residues.

Suspect screening strategy for pesticide application history based on characteristics of trace metabolites.

Pesticides are widely used to protect crops but can also threaten public health as they can remain in the environment for a long time. Additionally, some transformation products (TPs) of unknown toxicity, stability, or bioaccumulation properties can further be formed from the hydrolysis, photolysis and biodegradation of pesticides. The identification and quantification of those TPs can be challenging for environmental regulation and risk assessment due to a limited understanding about them. In this study, a suspect screening strategy for pesticide application history was developed and then used to organic products (tea). Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) was used to screen and identify the TPs in crops and their toxicity was subsequently predicted with the open-source software (ECOSAR and admetSAR). Finally, the SIRIUS software was applied and 142 TPs from 20 pesticides were identified in tea plants based on the fragmentation-degradation relationship. Of these, standards (level 1) and 53 were considered as tentatively identified (levels 2a and 2b). Some TPs were also found to be present in tea plants and soil after 65 days, thus indicating higher persistency or stability than parent pesticides. While others from diafenthiuron and neonicotinoids had higher predicted toxicity of daphnid, and demonstrated positive for honeybee toxicity. Suspect screening is a powerful tool to screen pesticide TPs on the complex matrix of crops. Such screening can provide potential evidence of pesticide application, especially in cases of illegal practices in organic farming.

Automatic Multi-Plug Filtration Cleanup Tip-Filtration with Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry Detection For 22 Pesticide Residues in Typical Vegetables.

An automatic multi-plug filtration cleanup (m-PFC) tip-filtration method was developed to reduce the manual operation workload in sample preparation. In this work, m-PFC was based on multi-walled carbon nanotubes mixed with primary secondary amines and anhydrous magnesium sulfate (MgSO4) in a packed column for analysis of pesticide residues followed by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Method validation was performed on 22 pesticide residues in carrot, spinach and leek, at spiked levels of 5, 10 and 50 µg/kg, respectively. The average recoveries were between 70.1 and 119.5% with associated relative standard deviations <20% (n = 6) indicating satisfactory accuracy and repeatability. Matrix-matched calibration curves were performed with the correlation coefficients (R2) higher than 0.9903 within a linearity range of 5-100 ng/mL. The limits of quantification were 5 µg/kg for all the pesticides in carrot, spinach and leek matrices. The developed method was successfully used to determine pesticide residues in market samples.

Metabolomic analysis on the mechanism of nanoselenium alleviating cadmium stress and improving the pepper nutritional value.

Selenium (Se) maintains soil-plant homeostasis in the rhizosphere and regulates signaling molecules to mitigate cadmium (Cd) toxicity. However, there has been no systematic investigation of the effects of nano-selenium (nano-Se) on the regulation of non-target metabolites and nutritional components in pepper plants under Cd stress. This study investigated the effects of Cd-contaminated soil stress and nano-Se (1, 5, and 20 mg/L) on the metabolic mechanism, fruit nutritional quality, and volatile organic compounds (VOCs) composition of pepper plants. The screening of differential metabolites in roots and fruit showed that most were involved in amino acid metabolism and capsaicin production. Amino acids in roots (Pro, Trp, Arg, and Gln) and fruits (Phe, Glu, Pro, Arg, Trp, and Gln) were dramatically elevated by nano-Se biofortification. The expression of genes of the phenylpropane-branched fatty acid pathway (BCAT, Fat, AT3, HCT, and Kas) was induced by nano-Se (5 mg/L), increasing the levels of capsaicin (29.6%), nordihydrocapsaicin (44.2%), and dihydrocapsaicin (45.3%). VOCs (amyl alcohol, linalool oxide, E-2-heptaldehyde, 2-hexenal, ethyl crotonate, and 2-butanone) related to crop resistance and quality were markedly increased in correspondence with the nano-Se concentration. Therefore, nano-Se can improve the health of pepper plants by regulating the capsaicin metabolic pathway and modulating both amino acid and VOC contents.

Application of insecticides on peppermint (Mentha × piperita L.) induces lignin accumulation in leaves by consuming phenolic acids and thus potentially deteriorates quality.

Irrational use of pesticides may lead to physiological and metabolic disorders in different crops. However, there are limited investigations on impacts of insecticides on physiology and biochemistry, secondary metabolic pathways, and associated quality of medicinal plants such as peppermint (Mentha × piperita L.). In this study, target metabolites in peppermint were monitored following foliar spraying of five insecticides: imidacloprid, pyriproxyfen, acetamiprid, chlorantraniliprole, and chlorfenapyr. Compared with the control, all insecticide treatments caused a significant loss of soluble protein (decreased by 22.3-38.7%) in peppermint leaves. Insecticides induced an increase in the levels of phytohormones jasmonic acid and abscisic acid in response to these chemical stresses. Among them, imidacloprid increased jasmonic acid by 388.3%, and pyriproxyfen increased abscisic acid by 98.8%. The contents of phenylpropanoid metabolites, including rutin, quercetin, apigenin, caffeic acid, 4-hydroxybenzoic acid, ferulic acid, syringic acid, and sinapic acid showed a decreasing trend, with pyriproxyfen decreasing the levels of quercetin and 4-hydroxybenzoic acid by 78.8% and 72.6%, respectively. Combined with correlation analysis, the content of lignin in leaves shows different degrees of negative correlations with several phenolic acids. It could be inferred that insecticides may trigger plant defense mechanisms that accumulate lignin (increased by 24.6-49.1%) in leaves by consuming phenolic acids to barricade absorption of insecticides. Through constructing networks between phytohormones and secondary metabolites, peppermint may regulate the contents of caffeic acid, 4-hydroxybenzoic acid, and sinapic acid by the antagonistic effect between salicylic acid and abscisic acid in response to insecticidal stresses. Principal component analysis and systemic cluster analysis revealed that the most pronounced changes in physiological indexes and metabolites were caused by the pyriproxyfen treatment. In conclusion, this study improves our understanding of the mechanism by which insecticides affect plant physiological and metabolic processes, thus potentially altering the quality and therapeutic value of peppermint as an example.

Feeding foliar nano-selenium biofortified panax notoginseng could reduce the occurrence of glycolipid metabolism disorder in mice caused by high-fat diets.

Nano-selenium (nano-Se) has been extensively explored as a biostimulant for improving the quality of grain crops. However, there are few reports about the effect on the medicinal components of Chinese herbal medicine cultured with nano-Se. Here, we sprayed nano-Se during the cultivation of Panax notoginseng (SePN), and measured the changes of medicinal components compared with conventional Panax notoginseng (PN). Furthermore, we identified a more pronounced effect of SePN on reducing obesity in animals compared with PN. By measuring antioxidant capacity, histopathology, gene expression related to glycolipid metabolism, and gut microbiota composition, we propose a potential mechanism for SePN to improve animal health. Compared with the control groups, foliar spraying of nano-Se increased saponins contents (Rb2, Rb3, Rc, F2, Rb2, and Rf) in the roots of Panax notoginseng, the content of Rb2 increased by 3.9 times particularly. Interestingly, animal studies indicated that taking selenium-rich Panax notoginseng (SePN) can further ameliorate liver antioxidation (SOD, MDA, and GSH) and enzyme activities involved in glycolipid metabolism (ATGL and PFK). It also relieved inflammation and regulated the expression of genes (MCAD, PPAR-α, and PCSK9) related to fatty acid oxidation. The abundance ratio of Firmicutes/Bacteroides and beneficial bacteria abundance (Bifidobacterium, Butyricimonas, and Parasutterella) in gut microbiota were improved relative to the control. In summary, the application of nano-Se on PN may effectively raise the content of Panax notoginseng saponins (PNS) and immensely lower the risk of metabolic disorders of glycolipids.

Nano-selenium enhances the antioxidant capacity, organic acids and cucurbitacin B in melon (Cucumis melo L.) plants.

Pesticides are widely used in melon production causing safety issues around the consumption of melon and increasing pathogen and insect tolerance to pesticides. This study investigated whether a nano-selenium (Nano-Se) spray treatment can improve resistance to biological stress in melon plants, reducing the need for pesticides, and how this mechanism is activated. To achieve this, we examine the ultrastructure and physio-biochemical responses of two melon cultivars after foliar spraying with Nano-Se. Nano-Se treatment reduced plastoglobulins in leaf mesophyll cells, thylakoid films were left intact, and compound starch granules increased. Nano-Se treatment also increased root mitochondria and left nucleoli intact. Nano-Se treatment enhanced ascorbate peroxidase, peroxidase, phenylalanine ammonia lyase, ß-1,3-glucanase, chitinase activities and their mRNA levels in treated melon plants compared to control plants (without Nano-Se treatments). Exogenous application of Nano-Se improved fructose, glucose, galactitol, stachyose, lactic acid, tartaric acid, fumaric acid, malic acid and succinic acid in treated plants compared to control plants. In addition, Nano-Se treatment enhanced cucurbitacin B and up-regulated eight cucurbitacin B synthesis-related genes. We conclude that Nano-Se treatment of melon plants triggered antioxidant capacity, photosynthesis, organic acids, and up-regulated cucurbitacin B synthesis-related genes, which plays a comprehensive role in stress resistance in melon plants.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion.

BACKGROUND: In recent years, metabolic products of pesticides have gained much attention due to their substantial characteristics as organic pollutants. So far, the behavior and metabolite levels of pesticide metabolites in crops have not been characterized well. In the present study, four registered pesticides (imidacloprid, diafenthiuron, malathion and chlorothalonil) were applied on tea plants in Fujian and Sichuan to characterize their metabolites residue pattern and dietary risk. RESULTS: Four pesticides dissipated first-order kinetics in the fresh tea leaves with the half-lives of 1.4-3.8 days. Nine metabolites were detected in the fresh tea leaves and green tea after processing. The metabolites residues showed an increasing trend first and then declined after treatment, and reached the maximum near the half-lives of pesticide. Compared with the parent pesticide, the total residue and acute risk (included the metabolites) increased by 1.7-105.2 times. Some metabolites, especially those whose parent pesticides have high water solubility and low Log Kow, will be more easily transferred to tea infusion. CONCLUSION: Pesticides were metabolized rapidly on tea plants after application, but the production of metabolites increased the health risk of tea consumption. These results could provide insights to use the pesticides in tea gardens and risk monitoring after application. © 2022 Society of Chemical Industry.

Method Development and Validation of Seven Pyrethroid Insecticides in Tea and Vegetable by Modified QuEChERS and HPLC-MS/MS.

This study developed a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for determining seven pyrethroid pesticide residues in tea, cucumber, and tomato via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The overall average recoveries of the seven pyrethroids were 72%-104% (relative standard deviation (RSD); 2.0%-16.1%, 89%-109% (RSD; 0.7%-17.3%), 82%-110% (RSD; 1.6%-17.1%) for tea, cucumber and tomato, respectively. The determination coefficient (R2), the limit of detection (LOD), and the limit of quantification (LOQ) were ≥ 0.99, 0.007-1.875 µg kg-1, and 0.025-6.250 µg kg-1, respectively. The method was successfully used to monitor the pyrethroid pesticide residues in market samples. HPLC-MS/MS rapidly, sensitively, and accurately determined the pyrethroid pesticide residues.

An ultralow concentration of Al-MOFs for turn-on fluorescence detection of aflatoxin B1 in tea samples.

A turn-on fluorescent sensing platform based on an ultralow concentration of Al-metal organic frameworks for the detection of aflatoxin B1 has been developed for the first time. This fluorescence turn-on sensor exhibits the largest fluorescence enhancement (or quenching) constant value of 179404 M-1 among all luminescence-based chemical sensors reported till date. Moreover, the sensor afforded a rapid detection of aflatoxin B1, with a linear response in the concentration range of 0.05-9.61 µM and a low detection limit of 11.67 ppb. Additionally, the fabricated sensor showed good repeatability, reproducibility, stability, and selectivity. Most importantly, the practical application of this sensor has been demonstrated by detecting aflatoxin B1 in complex tea samples with low relative standard deviation (≤7.72%; n = 3) and satisfactory recoveries. In summary, the proposed method has great potential as a simple, sensitive and selective strategy for monitoring aflatoxin B1 in food samples.