Changes in the metabolome of lettuce leaves due to exposure to mancozeb pesticide

GC-MS metabolomics of French lettuce (Lactuca Sativa L. var capitata) leaves exposed to bisphenol A via the hydroponic media

INTRODUCTION

Bisphenol A (BPA), an organic compound used to produce polycarbonate plastics and epoxy resins, has become a ubiquitous contaminant due to its high-volume production and constant release to the environment. Plant metabolomics can trace the stress effects induced by environmental contaminants to the variation of specific metabolites, making it an alternative way to study pollutants toxicity to plants. Nevertheless, there is an important knowledge gap in metabolomics applications in this area.

OBJECTIVE

Evaluate the influence of BPA in French lettuce (Lactuca Sativa L. var capitata) leaves metabolic profile by gas chromatography coupled to mass spectrometry (GC-MS) using a hydroponic system.

METHODS

Lettuces were cultivated in the laboratory to minimize biological variation and were analyzed 55 days after sowing (considered the plant's adult stage). Hexanoic and methanolic extracts with and without derivatization were prepared for each sample and analyzed by GC-MS.

RESULTS

The highest number of metabolites was obtained from the hexanoic extract, followed by the derivatized methanolic extract. Although no physical differences were observed between control and contaminated lettuce leaves, the multivariate analysis determined a statistically significant difference between their metabolic profiles. Pathway analysis of the most affected metabolites showed that galactose metabolism, starch and fructose metabolism and steroid biosynthesis were significantly affected by BPA exposure.

CONCLUSIONS

The preparation of different extracts from the same sample permitted the determination of metabolites with different physicochemical properties. BPA alters the leaves energy and membrane metabolism, plant growth could be affected at higher concentrations and exposition times.

Connecting metabolome and phenotype: recent advances in functional metabolomics tools for the identification of bioactive natural products

Covering: 1995 to 2023Advances in bioanalytical methods, particularly mass spectrometry, have provided valuable molecular insights into the mechanisms of life. Non-targeted metabolomics aims to detect and (relatively) quantify all observable small molecules present in a biological system. By comparing small molecule abundances between different conditions or timepoints in a biological system, researchers can generate new hypotheses and begin to understand causes of observed phenotypes. Functional metabolomics aims to investigate the functional roles of metabolites at the scale of the metabolome. However, most functional metabolomics studies rely on indirect measurements and correlation analyses, which leads to ambiguity in the precise definition of functional metabolomics. In contrast, the field of natural products has a history of identifying the structures and bioactivities of primary and specialized metabolites. Here, we propose to expand and reframe functional metabolomics by integrating concepts from the fields of natural products and chemical biology. We highlight emerging functional metabolomics approaches that shift the focus from correlation to physical interactions, and we discuss how this allows researchers to uncover causal relationships between molecules and phenotypes.

Comprehensive effects of thiamethoxam from contaminated soil on lettuce growth and metabolism

The second-generation neonicotinoid thiamethoxam, is prevalent in soils because of its extensive application and persistence. However, the comprehensive effects of thiamethoxam residue in soils on cultivated plants are still poorly understood. This study examined variations of growth state, physiological parameters, antioxidant activity, and metabolites in lettuce after thiamethoxam exposure; the removal effects of different washing procedures were also investigated. The results indicated that thiamethoxam in soils significantly increased the fresh weight, seedling height and chlorophyll content in lettuce, and also altered its lipid, carbohydrate, nucleotide and amino acids composition based on untargeted metabolomics. KEGG pathway analysis uncovered a disruption of lipid pathways in lettuce exposed to both low and high concentrations of thiamethoxam treatments. In addition, the terminal residues of thiamethoxam in lettuce were below the corresponding maximum residue limits stipulated for China. The thiamethoxam removal rates achieved by common washing procedures in lettuce ranged from 26.9% to 42.6%. This study thus promotes the understanding of the potential food safety risk caused by residual thiamethoxam in soils.

Comprehensive metabolome and growth effects of thiamethoxam uptake and accumulation from soil on pak choi

Extensive use of the neonicotinoid thiamethoxam (TMX) results in its deposition in soil, which can then be absorbed and translocated in vegetables. Here we analyzed the comprehensive effects of TMX on pak choi. The TMX translocation factor (TF) was 0.37-11.65 and 0.46-39.75 for low and high treatments over 28 d, respectively, indicating its ready ability to move from the roots to the leaves of these plants. This uptake was associated with significant decrease in the fresh weight, and increase in vitamin C (VC), soluble sugars and soluble solid of pak choi. A metabolomic analysis revealed that fatty acids and purine nucleosides significantly decreased, and flavonoids and carbohydrates increased in the presence of TMX. TMX exposure thus influenced plant growth and disrupted the carbohydrate and lipid metabolism pathways. Our study raises concerns for food safety risk associated with TMX-contaminated soil.

Non-target influence of imidacloprid residues on grape global metabolome and berry quality with the identification of metabolite biomarkers

This paper illustrates the non-target impact of imidacloprid (IM) residues on the grape global metabolome and biomarker identification with high-resolution mass spectrometry. IM was applied at the recommended dose (SD), and ten times SD (10 RD). The global metabolome analysis revealed that 21 metabolites were up- and down-regulated with IM SD treatment. In 10 RD, 9 metabolites were upregulated, and 28 were downregulated. Pathway enrichment analysis revealed the primary and secondary pathway disruption in grapes. Berry quality was affected with decrease in flavonoids by 32.97% in 10 RD; phenols were reduced by 53.93 in SD, 50.8% in 10 RD. The non-target and target study revealed the degradation of IM in grapes to desnitro-IM and IM-urea which were identified as a potential biomarker for IM residues in grapes, which would benefit the authentication of organic product. Overall, imidacloprid showed a significant impact on the grape metabolome and quality.

A comprehensive review on toxicological mechanisms and transformation products of tebuconazole: Insights on pesticide management

Tebuconazole has been widely applied over three decades because of its high efficiency, low toxicity, and broad spectrum, and it is still one of the most popular fungicides worldwide. Tebuconazole residues have been frequently detected in environmental samples and food, posing potential hazards for humans. Understanding the toxicity of pesticides is crucial to ensuring human and ecosystem health, but the toxic mechanisms and toxicity of tebuconazole are still unclear. Moreover, pesticides could transform into transformation products (TPs) that may be more persistent and toxic than their parents. Herein, the toxicities of tebuconazole to humans, mammals, aquatic organisms, soil animals, amphibians, soil microorganisms, birds, honeybees, and plants were summarized, and its TPs were reviewed. In addition, the toxicity of tebuconazole TPs to aquatic organisms and mammals was predicted. Tebuconazole posed potential developmental toxicity, genotoxicity, reproductive toxicity, mutagenicity, hepatotoxicity, neurotoxicity, cardiotoxicity, and nephrotoxicity, which were induced via reactive oxygen species-mediated apoptosis, metabolism and hormone perturbation, DNA damage, and transcriptional abnormalities. In addition, tebuconazole exhibited apparent endocrine-disrupting effects by modulating hormone levels and gene transcription. The toxicity of some TPs was equivalent to and higher than tebuconazole. Therefore, further investigation is necessary into the toxicological mechanisms of tebuconazole and the combined toxicity of a mixture of tebuconazole and its TPs.

Fungicides and strawberry pollination-Effects on floral scent, pollen attributes and bumblebee behavior

Fungicides are used in agriculture to protect crops from various fungal diseases. However, they may modulate the plants metabolism. Moreover, fungicides can accumulate in the environment and may cause toxic effects on non-target organisms such as nectar microbes and pollinators. Nectar microbes contribute to the volatile profile of flowers and can influence pollinators behaviour. Thus, fungicide treatment could potentially affect the pollination. In this study, we investigated the influence of fungicide treatment on floral attributes as well as the behavioural impact on bumblebees. In separate experiments, we used one or both strawberry cultivars (Fragaria × ananassa var. Darselect and Malwina), which were either kept untreated (control) or treated with either Cuprozin® progress or SWITCH® fungicide. We analysed various flower traits including volatiles, pollen weight, pollen protein, and the attraction of bumblebees towards the flowers in the greenhouse. Additionally, we analysed the viability of pollen and pollen live-to-dead ratio, as well as the composition of nectar fungi in the field. A treatment with Cuprozin® progress led to a lower emission of floral volatiles and a slightly lower pollen protein content. This had no impact on the visit latency of bumblebees but on the overall visit frequency of these flowers. The treatment with the fungicide SWITCH® resulted in a higher emission of floral volatiles as well as a delayed first visit by bumblebees. Furthermore, flowers of control plants were visited more often than those treated with the two fungicides. Plant-pollinator interactions are highly complex, with many contributing factors. Fungicides can have an impact on the pollen quality and pollinator attraction, potentially leading to an altered pollen dispersal by pollinators and a change in fruit quality.

UPLC-Q-TOF/MS-based metabolomic analysis reveals the effects of asomate on the citrus fruit

The regulation of the sugar-acid ratio is of great significance to the improvement of citrus fruit quality. The citric acid level in fruit is influenced by many factors. Among them, cultivar selection and production practices are the most important strategies under the grower's control. In recent years, an arsenic-containing preparation called "Tianmisu", with the main ingredient of asomate, has occasionally been reported to be used in citrus cultivation to improve the sweetness of fruits. In order to reveal the effects of the pesticide on citrus fruits, 'Harumi' tangor was treated with "Tianmisu", and the impact of this pesticide on fruit quality and metabolites was investigated through UPLC-Q-TOF/MS-based metabolomic analysis. Compared with the control, the concentration of titratable acidity, in particular citric acid, in the pulp of 'Harumi' tangor treated with the pesticide, was significantly reduced by 60.5%. The differences in metabolites between the pesticide-treated samples and the control were illustrated by Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA). The PLS-DA analysis demonstrated a clear discrimination, with R²Y and Q² values of 0.982 and 0.933 in the positive mode and 0.984 and 0.900 in the negative mode, respectively. A total of 155 compounds were identified, and 63 characteristic components were screened out from the pesticide-treated samples compared to the control. Aside from the upregulation observed for a few metabolites, the majority of the compounds, including citric acid and various lipids, were down-regulated in the treated citrus fruits compared to the control. This study can serve as a basis for understanding the regulatory mechanism of organic acids in citrus and will be helpful in developing different strategies to improve citrus quality.

Metabolomics-Based Mechanistic Insights into Revealing the Adverse Effects of Pesticides on Plants: An Interactive Review

In plant biology, metabolomics is often used to quantitatively assess small molecules, metabolites, and their intermediates in plants. Metabolomics has frequently been applied to detect metabolic alterations in plants exposed to various biotic and abiotic stresses, including pesticides. The widespread use of pesticides and agrochemicals in intensive crop production systems is a serious threat to the functionality and sustainability of agroecosystems. Pesticide accumulation in soil may disrupt soil-plant relationships, thereby posing a pollution risk to agricultural output. Application of metabolomic techniques in the assessment of the biological consequences of pesticides at the molecular level has emerged as a crucial technique in exposome investigations. State-of-the-art metabolomic approaches such as GC-MS, LC-MS/MS UHPLC, UPLC-IMS-QToF, GC/EI/MS, MALDI-TOF MS, and ¹H-HR-MAS NMR, etc., investigating the harmful effects of agricultural pesticides have been reviewed. This updated review seeks to outline the key uses of metabolomics related to the evaluation of the toxicological impacts of pesticides on agronomically important crops in exposome assays as well as bench-scale studies. Overall, this review describes the potential uses of metabolomics as a method for evaluating the safety of agricultural chemicals for regulatory applications. Additionally, the most recent developments in metabolomic tools applied to pesticide toxicology and also the difficulties in utilizing this approach are discussed.

Metabolomic Analysis Reveals the Effect of Insecticide Chlorpyrifos on Rice Plant Metabolism

Pesticides as important agricultural inputs play a vital role in protecting crop plants from diseases and pests; however, the effect of pesticides on crop plant physiology and metabolism is still undefined. In this study, the effect of insecticide chlorpyrifos at three doses on rice plant physiology and metabolism was investigated. Our results revealed that chlorpyrifos cause oxidative stress in rice plants and even inhibit plant growth and the synthesis of protein and chlorophyll at high doses. The metabolomic results suggested that chlorpyrifos could affect the metabolic profiling of rice tissues and a total of 119 metabolites with significant changes were found, mainly including organic acids, amino acids, lipids, polyphenols, and flavonoids. Compared to the control, the content of glutamate family amino acids were significantly disturbed by chlorpyrifos, where defense-related proline and glutathione were significantly increased; however, glutamic acid, N-acetyl-glutamic acid and N-methyl-glutamic acid were significantly decreased. Many unsaturated fatty acids, such as linolenic acid and linoleic acid, and their derivatives lysophospholipids and phospholipids, were significantly accumulated in chlorpyrifos groups, which could act as osmolality substances to help rice cells relieve chlorpyrifos stress. Three organic acids, aminobenzoic acid, quinic acid, and phosphoenolpyruvic acid, involved in plant defenses, were significantly accumulated with the fold change ranging from 1.32 to 2.19. In addition, chlorpyrifos at middle- and high-doses caused the downregulation of most flavonoids. Our results not only revealed the effect of insecticide chlorpyrifos on rice metabolism, but also demonstrated the value of metabolomics in elucidating the mechanisms of plant responses to stresses.

Transcriptomic and metabolomic investigation of metabolic disruption in Vigna unguiculata L. triggered by acetamiprid and cyromazine

A variety of pesticides are often used in agricultural management to control target pests but may trigger disruptions in the metabolism of nontarget organisms, ultimately affecting crop quality. Acetamiprid (ACE) and cyromazine (CYR) are two frequently used insecticides on cowpea, so it is critical to understand whether these two insecticides cause metabolic disorders in cowpea quality changes and the mechanism by which they do so. Here, we used metabolomic and transcriptomic methods to explore the mechanisms of the effects of ACE, CYR, and their mixture (MIX) on cowpea. In this study, ACE, CYR and MIX had no significant effects on plant biomass or growth status but decreased the contents of starch, soluble protein, and total flavonoids. All treatments reduced the total flavonoid content, but MIX showed the largest reduction of 10.02%. Metabolomic and transcriptomic analyses revealed that ACE markedly affected amino acid metabolism, and CYR and MIX affected sugar metabolism and flavonoid synthesis pathways. ACE and CYR reduced the levels of alanine, glutamic acid, isoleucine and phenylalanine and the expression of amino acid-related genes in cowpea, while MIX significantly increased the levels of most amino acids. All pesticide treatments reduced saccharide levels and related genes, with the most pronounced reduction in the MIX treatment. Exposure to ACE decreased the content of naringenin chalcone and quercetin and increased the content of anthocyanins in cowpeas, while MIX caused a significant decrease in the contents of quercetin and anthocyanins. According to the current study, single and mixed pesticides had different effects on the active ingredients of cowpea, with MIX causing the most significant decrease in the metabolite content of cowpea. These results provide important insights from a molecular perspective on how neonicotinoids and triazine insecticides affect cowpea metabolism.

Stereoselective metabolomic and lipidomic responses of lettuce (Lactuca sativa L.) exposing to chiral triazole fungicide tebuconazole

In this study, non-targeted and targeted metabolomics/lipidomics studies based on UPLC-QTOF-MS and UPLC-MS/MS were carried out to clarify the effects of tebuconazole and its different enantiomers on lettuce metabolites and lipids. Slight enantioselective degradation of tebuconazole was observed and six degradation metabolites were tentatively identified. The endogenous metabolites involved in carbohydrate metabolism, amino acid metabolism, nucleic acid metabolism, phenylpropanoid and flavonoid metabolism, vitamins, and lipid metabolism were significantly affected with enantioselectivity by tebuconazole exposure. Nucleotide metabolism and nicotinic acid metabolic network were significantly activated by the stimulation of tebuconazole. Rac- and (-)-R-tebuconazole caused the down-regulation of soluble sugars and subsequent amino acids and organic acids. Overall, lettuce exposed to tebuconazole was shown to have a significant impact on plant metabolism and lipid metabolism, with notable stereoselectivity. The results showed stereoselective toxicity of tebuconazole and provided a better understanding of its metabolomic and lipidomic effects on lettuce.

Metabolic disturbance in lettuce (Lactuca sativa) plants triggered by imidacloprid and fenvalerate

Intensive and indiscriminate use of insecticides in agroecosystems causes phytotoxic disturbances in non-target crops. However, the mechanisms by which plants reprogram cellular metabolites to resist and tolerate such agrochemicals remain unclear. Here, the interaction between lettuce plants with imidacloprid and fenvalerate was investigated by the complementary use of physiological and metabolomic analyses. Neither imidacloprid nor fenvalerate induced overt phytotoxicity in lettuce seedlings. The plant biomass, chlorophyll fluorescence, lipid peroxidation, and membrane integrity were not significantly affected by the selected insecticides. Flavonoid content decreased by 25% in lettuce leaves under fenvalerate exposure, whereas polyphenol and flavonoid contents were not significantly altered by imidacloprid. Although the content of most of the nutrient element in the leaves remained the same following pesticide treatment, iron content decreased by 28.1% under imidacloprid exposure but increased by 22.8% under fenvalerate exposure. Metabolomic analysis revealed that the selected insecticides induced extensive metabolic reprogramming in lettuce roots and shoots. Imidacloprid dramatically increased the metabolism of several amino acids (arginine, cysteine, homoserine, and 4-hydroxyisoleucine), whereas markedly decreased the metabolism of various carbohydrates (glucose, raffinose, maltotetraose, maltopentaose, and stachyose). Fenvalerate did not significantly alter amino acid metabolism but decreased carbohydrate metabolism. Additionally, the relative abundance of most organic acids and polyphenolic compounds decreased significantly after pesticide exposure. These results suggest that plants might program their primary and secondary metabolism to resist and tolerate insecticides. The findings of this study provide important information on how neonicotinoid and pyrethroid insecticides affect the health and physiological state of plants, which are ultimately associated with crop yield and quality.

Bioactive compounds in lettuce: Highlighting the benefits to human health and impacts of preharvest and postharvest practices

Lettuce is one of the most commonly consumed leafy vegetables worldwide and is available throughout the entire year. Lettuce is also a significant source of natural phytochemicals. These compounds, including glycosylated flavonoids, phenolic acids, carotenoids, the vitamin B groups, ascorbic acid, tocopherols, and sesquiterpene lactones, are essential nutritional bioactive compounds. This review aims to provide a comprehensive understanding of the composition of health-promoting compounds in different types of lettuce, the potential health benefits of lettuce in reducing the risks of chronic diseases, and the effect of preharvest and postharvest practices on the biosynthesis and accumulation of health-promoting compounds in lettuce.

Omics technologies used in pesticide residue detection and mitigation in crop

In agriculture, the convenience and efficacy of chemical pesticides have become inevitable to manage cultivated crop production. Here, we review the worldwide use of pesticides based on their categories, mode of actions and toxicity. Excessive use of pesticides may lead to hazardous pesticide residues in crops, causing adverse effects on human health and the environment. A wide range of high-tech-analytical methods are available to analyse pesticide residues. However, they are mostly time-consuming and inconvenient for on-site detection, calling for the development of biosensors that detect cellular changes in crops. Such new detection methods that combine biological and physicochemical knowledge may overcome the shortage in current farming to develop sustainable systems that support environmental and human health. This review also comprehensively compiles domestic pesticide residues removal tips from vegetables and fruits. Synthetic pesticide alternatives such as biopesticide and nanopesticide are greener to the environment. However, its safety assessment for large-scale application needs careful evaluation. Lastly, we strongly call for reversions of pesticide application trends based on the changing climate, which is lacking in the current scenario.

HR-MAS NMR Applications in Plant Metabolomics

Metabolomics is used to reduce the complexity of plants and to understand the underlying pathways of the plant phenotype. The metabolic profile of plants can be obtained by mass spectrometry or liquid-state NMR. The extraction of metabolites from the sample is necessary for both techniques to obtain the metabolic profile. This extraction step can be eliminated by making use of high-resolution magic angle spinning (HR-MAS) NMR. In this review, an HR-MAS NMR-based workflow is described in more detail, including used pulse sequences in metabolomics. The pre-processing steps of one-dimensional HR-MAS NMR spectra are presented, including spectral alignment, baseline correction, bucketing, normalisation and scaling procedures. We also highlight some of the models which can be used to perform multivariate analysis on the HR-MAS NMR spectra. Finally, applications of HR-MAS NMR in plant metabolomics are described and show that HR-MAS NMR is a powerful tool for plant metabolomics studies.

Applications of metabolomics in assessing ecological effects of emerging contaminants and pollutants on plants

Metabolomics, the global profiling of metabolite composition, is a powerful technique that can be applied to answer a diverse set of research questions concerning effects of toxicants on organisms. It has recently emerged as a tool to understand complex environmental perturbations in biological systems, especially at sub-lethal concentrations. Organisms can be affected by different stressors such as xenobiotics or increase in concentration of natural compounds such as nitrogen, phosphorous, and sulfur. Metabolomics has facilitated a better understanding of the effects of these perturbations on organisms such as plants, animals, and humans providing phenotypic and biological information in a high throughput manner. In this review, we will discuss recent applications of metabolomics to study the ecological effects of different environmental perturbations, including nanoparticles, pharmaceuticals and personal care products, pesticides, as well as the changes in natural compounds found in the environment with a focus on plant systems.

Effect of Imidacloprid Uptake from Contaminated Soils on Vegetable Growth

In the present study, the effect of imidacloprid uptake from contaminated soils on the growth of leaf vegetable Shanghaiqing was investigated. The result showed that during 35-day exposure, the concentration of imidacloprid (IMI) was in the order of vegetable shoots > vegetable roots > soil, indicating that IMI was more readily concentrated in vegetable shoots than in roots. Moreover, the biomass of IMI-treated vegetable shoots was comparable to that of the controls with early exposure, but was higher than that of the controls after 7-day exposure, showing that the test concentration of IMI could stimulate vegetable growth. The plant metabolic analysis of vegetable shoots using LC-QTOF/MS revealed that IMI may cause oxidative stress to the plant shoots with early exposure; however, the stressful situation of IMI seems to be relieved with the increase of some substances (such as spermidine and phenylalanine) with late exposure. Moreover, the upregulation of N-rich amino acids (glutamine, aspartate, and arginine) suggested that the process of fixing inorganic nitrogen in the plant should be enhanced, possibly contributing to enhanced growth rates. Additionally, four IMI's metabolites were identified by using MS-FINDER software, and the distribution of three metabolites in vegetable tissues was compared.

Sublethal insecticide exposure of an herbivore alters the response of its predator

Sublethal insecticide exposure poses risks for many non-target organisms and is a challenge for successful implementation of integrated pest management (IPM) programs. Next to detrimental effects of short-term insecticide exposure on fitness-related traits of organisms, also properties such as chemical signaling traits can be altered, which mediate intra- and interspecific communication. We investigated the effects of different durations of larval sublethal exposure to the pyrethroid lambda-cyhalothrin on performance traits of larvae and adults of the herbivorous mustard leaf beetle, Phaedon cochleariae. Moreover, by applying a direct contact and olfactometer bioassays, we determined the reaction of a generalist predator, the ant Myrmica rubra, towards insecticide-exposed and unexposed herbivore larvae and their secretions. Already short-term sublethal insecticide exposure of a few days caused a prolonged larval development and a reduced adult body mass of males. These effects may result from an insecticide-induced reduction in energy reserves. Furthermore, ants responded more frequently to insecticide-exposed than to unexposed larvae of P. cochleariae and their secretions. This increased responsiveness of ants towards insecticide-exposed larvae may be due to an insecticide-induced change in synthesis of chrysomelidial and epichrysomelidial, the dominant compounds of the larval secretion, which act defensive against various generalist predators. In conclusion, the results highlight that short-term insecticide exposure can impair the fitness of an herbivorous species due to both direct toxic effects and an increased responsiveness of predators. Consequently, exposure of single non-target species can have consequences for ecological communities in both natural habitats and IPM programs.

Effects of low-levels of three hexabromocyclododecane diastereomers on the metabolic profiles of pak choi leaves using high-throughput untargeted metabolomics approach

The ecological toxicity of hexabromocyclododecane (HBCD) on animals, including fish and mice, has been reported, but its effects in plants, particularly its toxic mechanism, have rarely been investigated. An untargeted metabolomics approach for comprehensive assessment was selected to study the alterations in the metabolic profiles in pak choi leaves induced by exposure to trace-level amounts of HBCD diastereomers over 30 days. A supervised orthogonal partial least-squares-discriminant analysis (OPLS-DA) was performed to investigate differences between the HBCD and control groups. The discriminating metabolites were identified using public databases. The results indicated that the toxicity of the HBCD diastereomers was ordered as γ-HBCD > α-HBCD > β-HBCD. 13 metabolites were identified as potential biomarkers to discriminate the presence of HBCD toxicity. The lipid, carbohydrate, nucleotide and amino acid metabolic pathways affected were found in accordance with animals and humans, and also HBCD could induce the interference of the secondary metabolite pathways. The system of the stress defences was activated, including signalling pathway, antioxidant defence system, shikimate and phenylpropanoid metabolism. The carbohydrate and amino acid metabolism were disturbed by HBCD intervention, and the lipid, amino acid and secondary metabolite metabolism were regulated for HBCD stress prevention. These results provide insights into the mechanism and degree of HBCD phytotoxicity.

Rhizosphere Protists Change Metabolite Profiles in Zea mays

Plant growth and productivity depend on the interactions of the plant with the associated rhizosphere microbes. Rhizosphere protists play a significant role in this respect: considerable efforts have been made in the past to reveal the impact of protist-bacteria interactions on the remobilization of essential nutrients for plant uptake, or the grazing induced changes on plant-growth promoting bacteria and the root-architecture. However, the metabolic responses of plants to the presence of protists or to protist-bacteria interactions in the rhizosphere have not yet been analyzed. Here we studied in controlled laboratory experiments the impact of bacterivorous protists in the rhizosphere on maize plant growth parameters and the bacterial community composition. Beyond that we investigated the induction of plant biochemical responses by separately analyzing above- and below-ground metabolite profiles of maize plants incubated either with a soil bacterial inoculum or with a mixture of soil bacteria and bacterivorous protists. Significantly distinct leaf and root metabolite profiles were obtained from plants which grew in the presence of protists. These profiles showed decreased levels of a considerable number of metabolites typical for the plant stress reaction, such as polyols, a number of carbohydrates and metabolites connected to phenolic metabolism. We assume that this decrease in plant stress is connected to the grazing induced shifts in rhizosphere bacterial communities as shown by distinct T-RFLP community profiles. Protist grazing had a clear effect on the overall bacterial community composition, richness and evenness in our microcosms. Given the competition of plant resource allocation to either defense or growth, we propose that a reduction in plant stress levels caused directly or indirectly by protists may be an additional reason for corresponding positive effects on plant growth.

Metabolomic Evaluation of the Quality of Leaf Lettuce Grown in Practical Plant Factory to Capture Metabolite Signature

Vegetables produce metabolites that affect their taste and nutritional value and compounds that contribute to human health. The quality of vegetables grown in plant factories under hydroponic cultivation, e.g., their sweetness and softness, can be improved by controlling growth factors including the temperature, humidity, light source, and fertilizer. However, soil is cheaper than hydroponic cultivation and the visual phenotype of vegetables grown under the two conditions is different. As it is not clear whether their metabolite composition is also different, we studied leaf lettuce raised under the hydroponic condition in practical plant factory and strictly controlled soil condition. We chose two representative cultivars, "black rose" (BR) and "red fire" (RF) because they are of high economic value. Metabolite profiling by comprehensive gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) resulted in the annotation of 101 metabolites from 223 peaks detected by GC-MS; LC-MS yielded 95 peaks. The principal component analysis (PCA) scatter plot showed that the most distinct separation patterns on the first principal component (PC1) coincided with differences in the cultivation methods. There were no clear separations related to cultivar differences in the plot. PC1 loading revealed the discriminant metabolites for each cultivation method. The level of amino acids such as lysine, phenylalanine, tryptophan, and valine was significantly increased in hydroponically grown leaf lettuce, while soil-cultivation derived leaf lettuce samples contained significantly higher levels of fatty-acid derived alcohols (tetracosanol and hexacosanol) and lettuce-specific sesquiterpene lactones (lactucopicrin-15-oxalate and 15-deoxylactucin-8-sulfate). These findings suggest that the metabolite composition of leaf lettuce is primarily affected by its cultivation condition. As the discriminant metabolites reveal important factors that contribute to the nutritional value and taste characteristics of leaf lettuce, we performed comprehensive metabolite profiling to identify metabolite compositions, i.e., metabolite signature, that directly improve its quality and value.

Sublethal insecticide exposure affects reproduction, chemical phenotype as well as offspring development and antennae symmetry of a leaf beetle

The area of agriculturally used land and following to that the use of pesticides are steadily increasing. Insecticides do not only reduce pest organisms on crops but can also affect non-target organisms when present in sublethal concentrations in the environment. We investigated the effects of an exposure to sublethal pyrethroid (lambda-cyhalothrin) concentrations, at doses 20 and 60 times lower than the LC₅₀, respectively, on reproductive traits and adult cuticular hydrocarbon (CHC) profiles of a leaf beetle (Phaedon cochleariae Fabricius). Furthermore, we tested for effects on growth and antennae symmetry of the offspring generation that was not exposed to the insecticide. Sublethal insecticide concentrations decreased the egg number produced by the adults and the hatching rate. Moreover, the chemical phenotype (CHC profile) of adults was altered in dependence of the insecticide treatment, with sex-specific effects. In the unexposed offspring of insecticide-exposed parents, a prolonged development time and a fluctuating asymmetry of the females' antennae were detected, revealing transgenerational effects. The insecticide effects on the CHC profiles of the parental generation might have been caused by changes in CHC precursors, which were potentially induced by the insecticide treatment of the insect diet. Such altered CHC pattern may have implications for intraspecific communication, e.g., in mate choice, as well as in an interspecific way, e.g., in interactions with other arthropod species. The observed detrimental transgenerational effects might be explainable by a reduced investment in the offspring, maternal transfer or epigenetic processes. An asymmetry of the antennae may lead to defects in the reception of chemical signals. In conclusion, the results disclose that, besides detrimental (transgenerational) effects on reproduction and development, an exposure to sublethal insecticide concentrations can impair the chemical communication between individuals, with impacts on the sender (i.e., the CHC profile) and the receiver (i.e., caused by asymmetry of the antennae).

Plant metabolism as studied by NMR spectroscopy

The study of plant metabolism impacts a broad range of domains such as plant cultural practices, plant breeding, human or animal nutrition, phytochemistry and green biotechnologies. Plant metabolites are extremely diverse in terms of structure or compound families as well as concentrations. This review attempts to illustrate how NMR spectroscopy, with its broad variety of experimental approaches, has contributed widely to the study of plant primary or specialized metabolism in very diverse ways. The review presents recent developments of one-dimensional and multi-dimensional NMR methods to study various aspects of plant metabolism. Through recent examples, it highlights how NMR has proved to be an invaluable tool for the global characterization of sample composition within metabolomic studies, and shows some examples of use for targeted phytochemistry, with a special focus on compound identification and quantitation. In such cases, NMR approaches are often used to provide snapshots of the plant sample composition. The review also covers dynamic aspects of metabolism, with a description of NMR techniques to measure metabolic fluxes - in most cases after stable isotope labelling. It is mainly intended for NMR specialists who would be interested to learn more about the potential of their favourite technique in plant sciences and about specific details of NMR approaches in this field. Therefore, as a practical guide, a paragraph on the specific precautions that should be taken for sample preparation is also included. In addition, since the quality of NMR metabolic studies is highly dependent on approaches to data processing and data sharing, a specific part is dedicated to these aspects. The review concludes with perspectives on the emerging methods that could change significantly the role of NMR in the field of plant metabolism by boosting its sensitivity. The review is illustrated throughout with examples of studies selected to represent diverse applications of liquid-state or HR-MAS NMR.

LC-MS Untargeted Metabolomics To Explain the Signal Metabolites Inducing Browning in Fresh-Cut Lettuce

Enzymatic browning is one of the main causes of quality loss in lettuce as a prepared and ready-to-eat cut salad. An untargeted metabolomics approach using UPLC-ESI-QTOF-MS was performed to explain the wound response of lettuce after cutting and to identify the metabolites responsible of browning. Two cultivars of Romaine lettuce with different browning susceptibilities were studied at short time intervals after cutting. From the total 5975 entities obtained from the raw data after alignment, filtration reduced the number of features to 2959, and the statistical analysis found that only 1132 entities were significantly different. Principal component analysis (PCA) clearly showed that these samples grouped according to cultivar and time after cutting. From those, only 15 metabolites belonging to lysophospholipids, oxylipin/jasmonate metabolites, and phenolic compounds were able to explain the browning process. These selected metabolites showed different trends after cutting; some decreased rapidly, others increased but decreased thereafter, whereas others increased during the whole period of storage. In general, the fast-browning cultivar showed a faster wound response and a higher raw intensity of some key metabolites than the slow-browning one. Just after cutting, the fast-browning cultivar contained 11 of the 15 browning-associated metabolites, whereas the slow-browning cultivar only had 5 of them. These metabolites could be used as biomarkers in breeding programs for the selection of lettuce cultivars with lower browning potential for fresh-cut applications.

Gibberellins producing Bacillus methylotrophicus KE2 supports plant growth and enhances nutritional metabolites and food values of lettuce

The nutritional quality of green leafy vegetables can be enhanced by application of plant beneficial micro-organisms. The present study was aimed to increase the food values of lettuce leaves by bacterial treatment. We isolated bacterial strain KE2 from Kimchi food and identified as Bacillus methylotrophicus by phylogenetic analysis. The beneficial effect of B. methylotrophicus KE2 on plants was confirmed by increasing the percentage of seed germination of Lactuca sativa L., Cucumis melo L., Glycine max L. and Brassica juncea L. It might be the secretion of array of gibberellins (GA1, GA3, GA7, GA8, GA9, GA12, GA19, GA20, GA24, GA34 and GA53) and indole-acetic acid from B. methylotrophicus KE2. The mechanism of plant growth promotion via their secreted metabolites was confirmed by a significant increase of GA deficient mutant rice plant growth. Moreover, the bacterial association was favor to enhance shoot length, shoot fresh weight and leaf width of lettuce. The higher concentration of protein, amino acids (Asp, Thr, Ser, Glu, Gly, Ala, Leu, Tyr and His), gama-aminobutric acid and fructose was found in bacterial culture (KE2) applied plants. The macro and micro minerals such as K, Mg, Na, P, Fe, Zn and N were also detected as significantly higher quantities in bacteria treated plants than untreated control plants. In addition, the carotenoids and chlorophyll a were also increased in lettuce at bacterial inoculation. The results of this study suggest that B. methylotrophicus KE2 application to soil helps to increase the plant growth and food values of lettuce.

Feasible Management of Southern Corn Leaf Blight via Induction of Systemic Resistance by Bacillus cereus C1L in Combination with Reduced Use of Dithiocarbamate Fungicides

Dithiocarbamate fungicides such as maneb and mancozeb are widely used nonsystemic protectant fungicides to control various plant fungal diseases. Dithiocarbamate fungicides should be frequently applied to achieve optimal efficacy of disease control and avoid either decline in effectiveness or wash-off from leaf surface. Dithiocarbamates are of low resistance risk but have the potential to cause human neurological diseases. The objective of this study was to develop a strategy to effectively control plant disease with reduced use of dithiocarbamtes. Southern corn leaf blight was the model pathosystem for the investigation. When corn plants were drench-treated with Bacillus cereus C1L, a rhizobacterium able to induce systemic resistance in corn plants against southern leaf blight, frequency of spraying dithiocarbamate fungicides could be decreased. The treatment of B. cereus C1L was able to protect maize from southern leaf blight while residues of dithiocarbamates on leaf surface were too low to provide sufficient protection. On the other hand, frequent sprays of mancozeb slightly but significantly reduced growth of corn plants under natural conditions. In contrast, application of B. cereus C1L can significantly promote growth of corn plants whether sprayed with mancozeb or not. Our results provide the information that plant disease can be well controlled by rhizobacteria-mediated induced systemic resistance in combination with reduced but appropriate application of dithiocarbamate fungicides just before a heavy infection period. An appropriate use of rhizobacteria can enhance plant growth and help plants overcome negative effects caused by dithiocarbamates.

High resolution magic angle spinning NMR spectroscopy reveals that pectoralis muscle dystrophy in chicken is associated with reduced muscle content of anserine and carnosine

Increased incidences of pectoralis muscle dystrophy are observed in commercial chicken products, but the muscle physiological causes for the condition remain to be identified. In the present study a high-resolution magic angle spinning (HR-MAS) proton ((1)H) NMR spectroscopic examination of intact pectoralis muscle samples (n=77) were conducted to explore metabolite perturbations associated with the muscle dystrophy condition for the very first time. Both in chicken with an age of 21 and 31days, respectively, pectoralis muscle dystrophy was associated with a significantly lower content of anserine (p=0.034), carnosine (p=0.019) and creatine (p=0.049). These findings must be considered intriguing as they corroborate that characteristic muscle di-peptides composed of β-alanine and histidine derivatives such as anserine are extremely important in homeostasis of contractile muscles as a results of their role as buffering, anti-oxidative, and anti-glycation capacities.

Effect of organochlorine pesticides exposure on the maize root metabolome assessed using high-resolution magic-angle spinning (1)H NMR spectroscopy

(1)H-HRMAS NMR-based metabolomics was used to better understand the toxic effects on maize root tips of organochlorine pesticides (OCPs), namely lindane (γHCH) and chlordecone (CLD). Maize seedlings were exposed to 2.5 μM γHCH (mimicking basic environmental contaminations) for 7 days and compared to 2.5 μM CLD and 25 μM γHCH for 7 days (mimicking hot spot contaminations). The (1)H-HRMAS NMR-based metabolomic profiles provided details of the changes in carbohydrates, amino acids, tricarboxylic acid (TCA) cycle intermediates and fatty acids with a significant separation between the control and OCP-exposed root tips. First of all, alterations in the balance between glycolysis/gluconeogenesis were observed with sucrose depletion and with dose-dependent fluctuations in glucose content. Secondly, observations indicated that OCPs might inactivate the TCA cycle, with sizeable succinate and fumarate depletion. Thirdly, disturbances in the amino acid composition (GABA, glutamine/glutamate, asparagine, isoleucine) reflected a new distribution of internal nitrogen compounds under OCP stress. Finally, OCP exposure caused an increase in fatty acid content, concomitant with a marked rise in oxidized fatty acids which could indicate failures in cell integrity and vitality. Moreover, the accumulation of asparagine and oxidized fatty acids with the induction of LOX3 transcription levels under OCP exposure highlighted an induction of protein and lipid catabolism. The overall data indicated that the effect of OCPs on primary metabolism could have broader physiological consequences on root development. Therefore, (1)H-HRMAS NMR metabolomics is a sensitive tool for understanding molecular disturbances under OCP exposure and can be used to perform a rapid assessment of phytotoxicity.

Two dimensional NMR spectroscopic approaches for exploring plant metabolome: A review

Today, most investigations of the plant metabolome tend to be based on either nuclear magnetic resonance (NMR) spectroscopy or mass spectrometry (MS), with or without hyphenation with chromatography. Although less sensitive than MS, NMR provides a powerful complementary technique for the identification and quantification of metabolites in plant extracts. NMR spectroscopy, well appreciated by phytochemists as a particularly information-rich method, showed recent paradigm shift for the improving of metabolome(s) structural and functional characterization and for advancing the understanding of many biological processes. Furthermore, two dimensional NMR (2D NMR) experiments and the use of chemometric data analysis of NMR spectra have proven highly effective at identifying novel and known metabolites that correlate with changes in genotype or phenotype. In this review, we provide an overview of the development of NMR in the field of metabolomics with special focus on 2D NMR spectroscopic techniques and their applications in phytomedicines quality control analysis and drug discovery from natural sources, raising more attention at its potential to reduce the gap between the pace of natural products research and modern drug discovery demand.