A Dissipation Pattern of Gibberellic Acid and Its Metabolite, Isogibberellic Acid, during Tea Planting, Manufacturing, and Brewing

Colloidal gold immunochromatographic assay for the detection of total aflatoxins in cereals

Aflatoxins (AFTs) are highly carcinogenic and mainly contaminate cereals. In this study, we designed and screened a hapten by analyzing the same characteristic groups of AFTs (AFB1, AFB2, AFG1 and AFG2), prepared a monoclonal antibody (mAb) 4C11 with a high sensitivity and specificity that can simultaneously detect all the main AFTs, and established a colloidal gold immunochromatographic assay (CG-ICA) for the detection of AFTs in cereals. The limits of detection (LODs) were 0.77 μg/kg, 1.40 μg/kg and 0.71 μg/kg for wheat, rice and maize, respectively, with linear ranges of 1.17-5.52 μg/kg, 1.84-5.20 μg/kg and 1.26-8.95 μg/kg, respectively. The spiked recoveries of AFTs samples ranged from 95.6 % to 104.2 %, and the positive samples further validated the reliability of the method. The results demonstrated that the method can be used for rapid, sensitive and efficient on-site detection of AFTs in cereals.

Gibberellin 2-oxidase 1(CsGA2ox1) involved gibberellin biosynthesis regulates sprouting time in camellia sinensis

BACKGROUND

Tea is an important cash crop and buds are its main product. To elucidate the molecular mechanism of the sprouting time of tea plants, 'Yuchunzao', which was an early sprouting tea cultivar, was studied. 'Echa 1', sprout one week later than 'Yuchunzao' in spring, was used as the control.

RESULTS

A total of 26 hormonal compounds and its derivatives in tea plants were qualified by using Ultra Performance Liquid Chromatography-Tandem mass spectrometry (UPLC-MS/MS). The result showed that GA20, GA3 and ICA were significantly different in 'Yuchunzao' than in 'Echa 1', with GA20 and GA3 up-regulated and ICA down-regulated. Based on the Illumina platform, transcriptome analysis revealed a total of 5,395 differentially expressed genes (DEGs). A diterpenoid biosynthesis related gene, gibberellin 2-oxidase 1 (CsGA2ox1), was downregulated in 'Yuchunzao' compared to 'Echa 1'. CsGA2ox1 regulate the transformation of GA different forms in plants. The relative expression of CsGA2ox1 showed an adverse trend with the content of GA20 and GA3. Our results suggest that down regulation of CsGA2ox1 resulted in the accumulation of GA3 and GA20, and then promoted sprout of 'Yuchunzao'.

CONCLUSION

This study provides theoretical basis of tea plants sprout and guides the tea breeding in practice.

Enhanced phytoremediation of cadmium-contaminated soil using chelating agents and plant growth regulators: effect and mechanism

The heavy metal cadmium (Cd) is a major threat to food safety and human health. Phytoremediation is the most widely used remediation technology, and how to improve the remediation efficiency of phytoremediation has become a key issue. In this study, we constructed an intensive phytoremediation technology for remediation of Cd-contaminated soil with biodegradable chelating agent and plant growth regulator combined with maize and investigated the mechanism of this technology. The results showed that the best remediation effect was achieved in the treatment with 10-6 mol l-1 gibberellic acid (GA3) and 6 mmol kg-1 aspartate diethoxysuccinic acid (AES) combined with maize. In this treatment, the total biomass and extraction efficiency of maize were 3.6 and 8.67 times higher than those of the control, respectively, and the antioxidant enzyme activities of maize were also increased. The soil was enriched with dominant bacterial genera that promote plant growth and metabolism and tolerance to heavy metal stress, which in turn promoted maize growth and Cd accumulation. Structural equation modelling results indicated a large effect of plant Cd concentration and plant antioxidant enzyme activity on plant Cd extraction. The enhanced phytoremediation technology showed good potential for safe use of Cd-contaminated soil.

Dissipation, residue distribution, and risk assessment of ethiprole and its metabolites in rice under various open field conditions

BACKGROUND

Ethiprole has been registered to control planthoppers in rice fields for many years in Asia. However, its dissipation and residues in rice under natural field conditions and health hazards are largely unclear. In the present study, a modified QuEChERS (i.e. Quick Easy Cheap Effective Rugged Safe) and high-performance liquid chromatography-tandem mass spectrometry method was established to detect ethiprole and its metabolites, ethiprole amide and ethiprole sulfone, in brown rice, rice husks, and rice straw. The field experiments were implemented in 12 representative provinces of China under Good Agricultural Practices aiming to investigate the fate and terminal residues of ethiprole and its metabolites in rice. Finally, the dietary risk of ethiprole was evaluated.

RESULTS

The average recoveries of these analytes in all matrices were 86.4-99.0% with a repeatability of 0.575-9.38%. The limits of quantification for each compound were 0.01 mg kg-1 . Dissipation of ethiprole followed the single first-order, first + first-order, and first-order multi-compartment kinetic models with a half-life of 2.68-8.99 days in rice husks. The dissipation half-life of ethiprole combining all metabolites was 5.20-16.2 days in rice husks. The terminal residues of ethiprole and its metabolites at preharvest intervals of 21 days were < 0.011, 0.25, and 0.20 mg kg-1 in brown rice, rice husks, and rice straw, respectively. Ethiprole amide was undetectable in all matrices, and the risk quotient of ethiprole was far less than 100%.

CONCLUSION

Ethiprole rapidly converted to ethiprole sulfone in rice, and ethiprole and ethiprole sulfone mainly remained in rice husks and straws. The dietary risk of ethiprole was acceptable for Chinese consumers. © 2023 Society of Chemical Industry.

Detection methods, migration patterns, and health effects of pesticide residues in tea

Due to its rich health benefits and unique cultural charm, tea drinking is increasingly popular with the public in modern society. The safety of tea is the top priority that affects the development of tea industry and the health of consumers. During the process of tea growth, pesticides are used to prevent the invasion of pests and diseases with maintaining high quality and stable yield. Because hot water brewing is the traditional way of tea consumption, water is the main carrier for pesticide residues in tea into human body accompanied by potential risks. In this review, pesticides used in tea gardens are divided into two categories according to their solubility, among which water-soluble pesticides pose a greater risk. We summarized the methods of the sample pretreatment and detection of pesticide residues and expounded the migration patterns and influencing factors of tea throughout the process of growth, processing, storage, and consumption. Moreover, the toxicity and safety of pesticide residues and diseases caused by human intake were analyzed. The risk assessment and traceability of pesticide residues in tea were carried out, and potential eco-friendly improvement strategies were proposed. The review is expected to provide a valuable reference for reducing risks of pesticide residues in tea and ensuring the safety of tea consumption.

The metabolism and dissipation behavior of tolfenpyrad in tea: A comprehensive risk assessment from field to cup

The metabolites of pesticides usually require rational risk assessment. In the present study, the metabolites of tolfenpyrad (TFP) in tea plants were identified using UPLC-QToF/MS analysis, and the transfer of TFP and its metabolites from tea bushes to consumption was studied for a comprehensive risk assessment. Four metabolites, PT-CA, PT-OH, OH-T-CA, and CA-T-CA, were identified, and PT-CA and PT-OH were detected along with dissipation of the parent TFP under field conditions. During processing, 3.11-50.00 % of TFP was further eliminated. Both PT-CA and PT-OH presented a downward trend (7.97-57.89 %) during green tea processing but an upward trend (34.48-124.17 %) during black tea manufacturing. The leaching rate (LR) of PT-CA (63.04-101.03 %) from dry tea to infusion was much higher than that of TFP (3.06-6.14 %). As PT-OH was no longer detected in tea infusions after 1 d of TFP application, TFP and PT-CA were taken into account in the comprehensive risk assessment. The risk quotient (RQ) assessment indicated a negligible health risk, but PT-CA posed a greater potential risk than TFP to tea consumers. Therefore, this study provides guidance for rational TFP application and suggests the sum of TFP and PT-CA residues as the maximum residual limit (MRL) in tea.

Transformation kinetics and mechanism of gibberellic acid with ferrihydrite: Building a novel adsorption-transformation multi-step kinetic model

Gibberellic acid (GA₃), a widely used phytohormone, is easily transformed into more toxic products. The soil and groundwater environment are an important sink for GA₃, but its transformation catalyzed by soil minerals has not been studied. In this study, the transformation kinetics and mechanism of GA₃ with ferrihydrite (Fh) were examined through kinetic batch experiments, microscopic-spectroscopic investigation and mathematical modeling. The results showed that rapid adsorption of GA₃ on Fh occurred in the first 4 h, followed by a catalytic pseudo-first-order transformation of the parent compound and products generation (4 h-30 d). Fh predominantly enhanced the transformation of GA₃ into Iso-GA₃ which was further hydrolyzed into OH-GA₃, in which adsorption was a prerequisite for transformation. The catalytic transformation likely resulted from the surface hydroxy of Fh, which not only stabilized the transformation intermediates by forming surface complexes with the carboxyl group of GA₃ and its products, but also served as a powerful nucleophile to attack the γ-lactone of GA₃ and Iso-GA₃. Based on the catalytic isomerization and hydrolysis mechanism of GA₃ with Fh, a novel adsorption-transformation multi-step kinetic conceptual model and mathematical model were developed. This model fitted the measured data well (R² > 0.97) and the fitted parameters suggested that the transformation rate constants of the transformation of GA₃ into Iso-GA₃ and the transformation of Iso-GA₃ into OH-GA₃ were facilitated with Fh by ∼26 and ∼9 times, respectively. The multi-step kinetic model has great potential in simulating GA₃ fate in soil and groundwater to assess its environmental health risk.

(+)-Catechin, epicatechin and epigallocatechin gallate are important inducible defensive compounds against Ectropis grisescens in tea plants

The tea plant, Camellia sinensis (L.) O. Kuntze, is an economically important, perennial woody plant rich in catechins. Although catechins have been reported to play an important role in plant defences against microbes, their roles in the defence of tea plants against herbivores remain unknown. In this study, we allowed the larvae of Ectropis grisescens, a leaf-feeding pest, to feed on the plants, and alternatively, we wounded the plants and then treated them with E. grisescens oral secretions (WOS). Both approaches triggered jasmonic acid-, ethylene- and auxin-mediated signalling pathways; as a result, plants accumulated three catechin compounds: (+)-catechin, epicatechin and epigallocatechin. Not only was the mass of E. grisescens larvae fed on plants previously infested with E. grisescens or treated with WOS significantly lower than that of larvae fed on controls, but also artificial diet supplemented with epicatechin, (+)-catechin or epigallocatechin gallate reduced larval growth rates. In addition, the exogenous application of jasmonic acid, ethylene or auxin induced the biosynthesis of the three catechins, which, in turn, enhanced the resistance of tea plants to E. grisescens, leading to the coordination of the three signalling pathways. Our results suggest that the three catechins play an important role in the defences of tea plants against E. grisescens.

Insights into stress degradation behavior of gibberellic acid by UHPLC Q-Exactive Orbitrap mass spectrometry

Gibberellic acid (GA₃) is widely applied in agriculture and food worldwide. Profiling the degradation products and their formation pattern under stress are helpful for deeply understanding GA₃ regulating plant physiology and GA₃ safety in agricultural crops. This study firstly investigated the degradation behavior of GA₃. Different stress factors such as light, pH and temperatures were investigated through photolysis and hydrolysis experiments. Five degradation products were identified using ultra high-performance liquid chromatography Q-Exactive Orbitrap mass spectrometry (UHPLC Q-Exactive Orbitrap MS). Three degradation products were produced under ultraviolet photolysis conditions. Two isomers (iso-GA₃ and gibberellenic acid) were formed under alkaline conditions. In order to characterize each degradation product, complete mass fragmentation pathways of all analytes were initially established. These results could provide a practical reference for the safety of agricultural products and the guidance for scientific application of GA₃ and proposed storage conditions of GA₃.

Impacts of n-acetyl cysteine on gibberellic acid-induced hepatorenal dysfunction through modulation of pro-inflammatory cytokines, antifibrotic and antioxidant activity

The extensive usage of gibberellic acid (GA3) in agriculture and plant growth is generally associated with enormous human and public health hazards. The present research assesses the impact of n-acetyl cysteine (NAC) on the hepatorenal injury persuaded by GA3 for this purpose, After two weeks of adaptation twenty-four rats allocated into four groups (6 rats/group) as follows: control group, supplied with saline only; n-acetyl cysteine (NAC) group, provided with 150 mg/kg/bw by stomach tube (orally) dissolved in saline; Positive GA3 group, received GA3 (55 mg/kg/bw) orally; Protective group received NAC (150 mg/kg/bw) and GA3 (55 mg/kg/bw) as in NAC and GA3 groups. Rats received their treatments for consecutive 3 weeks. On day 22, rats were anesthetized, then euthanized. Blood and tissue samples were obtained for biochemical, antioxidants markers analysis, gene expression, and histopathological examination. Our results revealed significant changes in serum AST, ALT, urea, uric acid, total protein, and albumin levels with a substantial rise of MDA and NO concentration in GA3 treated rats along with a considerable decrease of the GSH and overexpression of the inflammatory hepatic and renal cytokines (IL-10, TNF-α, NOS) and fibrotic gene expression TGF-β1, and α-SMA, with boost expression of nuclear factor-kappa (NF_k B). NAC co-administered with GA3 significantly normalized the kidney and liver function and the antioxidant state, besides normal histological structure of both liver and kidney tissue and downregulated expression of the pro-inflammatory cytokines as well as, fibrogenic gene expression. PRACTICAL APPLICATIONS: The current study confirmed that GA3 induced hepto-renal dysfunction that was ameliorated by NAC administration. Moreover, our findings confirmed the antioxidant capability of n-acetyl cysteine and afford robust evidence about the ameliorative effect of the n-acetyl cysteine to attenuate the hepatorenal injury induced by gibberellic acid through modulation of the antioxidant defense system fibrogenic, and pro-inflammatory cytokines expression.