Metabolomic analysis with GC-MS to reveal potential metabolites and biological pathways involved in Pb &Cd stress response of radish roots

Metabolic regulation mechanism of melatonin for reducing cadmium accumulation and improving quality in rice

Melatonin acts as a potential regulator of cadmium (Cd) tolerance in rice. However, its practical value in rice production remains unclear. To validate the hypothesis that melatonin affects Cd accumulation and rice quality, a series of experiments were conducted. The results showed that exogenous melatonin application was associated with reduced Cd accumulation (23-43%) in brown rice. Fourier transform infrared spectroscopy (FTIR) analysis showed that exogenous melatonin affected the rice protein secondary structure and starch short-range structure. Metabolomics based on LC-MS/MS revealed that exogenous melatonin altered the brown rice metabolic profile, decreased fatty acid metabolite content, but increased amino acid metabolite, citric acid, melatonin biosynthetic metabolite, and plant hormone contents. These findings indicate that exogenous melatonin can effectively reduced Cd accumulation and improve rice quality through metabolic network regulation, serving as an effective treatment for rice cultivated in Cd-contaminated soil.

Molecular Networking-Based Metabolome, In Vitro Antidiabetic and Anti-Inflammatory Effects of Breonadia salicina (Vahl) Hepper & J.R.I. Wood

Breonadia salicina (Vahl) Hepper & J.R.I. Wood is widely distributed throughout Africa. It is used ethnobotanically to treat various diseases. However, the metabolic profile of the Breonadia species is not well characterized and the metabolites that are responsible for the bioactivity of this plant remain unknown. Therefore, there is a need to determine the phytochemical and bioactivity profile to identify metabolites that contribute to the antidiabetic, anti-inflammatory and antiproliferation activity, including the genotoxicity and cytotoxic effects, of Breonadia salicina. The study is aimed at exploring the metabolomic profile antidiabetic, anti-inflammatory and antiproliferation activity, as well as the genotoxicity and cytotoxicity effects, of constituents of B. salicina. The compounds in the B. salicina extract were analyzed by ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS), and the resultant data were further analyzed using a molecular networking approach. The crude stem bark and root extracts showed the highest antidiabetic activity against α-amylase at the lowest test concentration of 62.5 µg/mL, with 74.53 ± 0.74% and 79.1 ± 1.5% inhibition, respectively. However, the crude stem bark and root extracts showed the highest antidiabetic activity against α-glucosidase at the lowest test concentration of 31.3 µg/mL, with 98.20 ± 0.15% and 97.98 ± 0.22% inhibition, respectively. The crude methanol leaf extract showed a decrease in the nitrite concentration at the highest concentration of 200 µg/mL, with cell viability of 90.34 ± 2.21%, thus showing anti-inflammatory activity. No samples showed significant cytotoxic effects at a concentration of 10 µg/mL against HeLa cells. Furthermore, a molecular network of Breonadia species using UPLC-QTOF-MS with negative mode electrospray ionization showed the presence of organic oxygen compounds, lipids, benzenoids, phenylpropanoids and polyketides. These compound classes were differentially distributed in the three different plant parts, indicating the chemical differences between the stem bark, root and leaf extracts of B. salicina. Therefore, the identified compounds may contribute to the antidiabetic and anti-inflammatory activity of Breonadia salicina. The stem bark, root and leaf extracts of B. salicina yielded thirteen compounds identified for the first time in this plant, offering a promising avenue for the discovery of new lead drugs for the treatment of diabetes and inflammation. The use of molecular networking produced a detailed phytochemical overview of this Breonadia species. The results reported in this study show the importance of searching for bioactive compounds from Breonadia salicina and provide new insights into the phytochemical characterization and bioactivity of different plant parts of Breonadia salicina.

Applications of chromatographic methods in metabolomics: A review

Chromatography is a robust and reliable separation method that can use various stationary phases to separate complex mixtures commonly seen in metabolomics. This review examines the types of chromatography and stationary phases that have been used in targeted or untargeted metabolomics with methods such as mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. General considerations for sample pretreatment and separations in metabolomics are considered, along with the various supports and separation formats for chromatography that have been used in such work. The types of liquid chromatography (LC) that have been most extensively used in metabolomics will be examined, such as reversed-phase liquid chromatography and hydrophilic liquid interaction chromatography. In addition, other forms of LC that have been used in more limited applications for metabolomics (e.g., ion-exchange, size-exclusion, and affinity methods) will be discussed to illustrate how these techniques may be utilized for new and future research in this field. Multidimensional LC methods are also discussed, as well as the use of gas chromatography and supercritical fluid chromatography in metabolomics. In addition, the roles of chromatography in NMR- vs. MS-based metabolomics are considered. Applications are given within the field of metabolomics for each type of chromatography, along with potential advantages or limitations of these separation methods.

Influence of Cold Stress on Physiological and Phytochemical Characteristics and Secondary Metabolite Accumulation in Microclones of Juglans regia L

The current study investigated the impact of cold stress on the morphological, physiological, and phytochemical properties of Juglans regia L. (J. regia) using in vitro microclone cultures. The study revealed significant stress-induced changes in the production of secondary antioxidant metabolites. According to gas chromatography-mass spectrometry (GC-MS) analyses, the stress conditions profoundly altered the metabolism of J. regia microclones. Although the overall spectrum of metabolites was reduced, the production of key secondary antioxidant metabolites significantly increased. Notably, there was a sevenfold (7×) increase in juglone concentration. These findings are crucial for advancing walnut metabolomics and enhancing our understanding of plant responses to abiotic stress factors. Additionally, study results aid in identifying the role of individual metabolites in these processes, which is essential for developing strategies to improve plant resilience and tolerance to adverse conditions.

Video parameters for action observation training in stroke rehabilitation: a scoping review

PURPOSE

Action observation training (AOT) is a therapeutic approach used in stroke rehabilitation. Videos form the core of AOT, and knowledge of constituent parameters is essential to make the intervention robust and generalizable. Currently, there is a dearth of available information on video parameters to be used for AOT. Our purpose was to identify and describe the parameters that constitute AOT videos for stroke rehabilitation.

METHOD

Electronic databases like PubMed, CINAHL, Scopus, Web of Science, ProQuest, and Ovid SP from inception to date according to PRISMA-ScR guidelines. Title, abstract, and full-text screening were done independently by two authors, with a third author for conflict resolution. Data on video parameters like length, quality, perspective, speed, screen size and distance, sound, and control videos were extracted.

RESULTS

Seventy studies were included in this review. The most-reported parameters were video length (85.71%) and perspective of view (62.85%). Movement speed (7.14%) and sound (8.57%) were the least reported. Static landscapes or geometrical patterns were found suitable as control videos.

CONCLUSION

Most video parameters except for length and perspective of view remain underreported in AOT protocols. Future studies with better descriptions of video parameters are required for comprehensive AOT interventions and result generalisation.

Metabolomics reveals the phytotoxicity mechanisms of foliar spinach exposed to bulk and nano sizes of PbCO3

PbCO3 is an ancient raw material for Pb minerals and continues to pose potential risks to the environment and human health through mining and industrial processes. However, the specific effects of unintentional PbCO3 discharge on edible plants remain poorly understood. This study unravels how foliar application of PbCO3 induces phytotoxicity by potentially influencing leaf morphology, photosynthetic pigments, oxidative stress, and metabolic pathways related to energy regulation, cell damage, and antioxidant defense in Spinacia oleracea L. Additionally, it quantifies the resultant human health risks. Plants were foliarly exposed to PbCO3 nanoparticles (NPs) and bulk products (BPs), as well as Pb2+ at 0, 5, 10, 25, 50, and 100 mg·L-1 concentrations once a day for three weeks. The presence and localization of PbCO3 NPs inside the plant cells were confirmed by TEM-EDS analysis. The maximum accumulation of total Pb was recorded in the root (2947.77 mg·kg-1 DW for ion exposure), followed by the shoot (942.50 mg·kg-1 DW for NPs exposure). The results revealed that PbCO3 and Pb2+ exposure had size- and dose-dependent inhibitory effects on spinach length, biomass, and photosynthesis attributes, inducing impacts on the antioxidase activity of CAT, membrane permeability, and nutrient elements absorption and translocation. Pb2+ exhibited pronounced toxicity in morphology and chlorophyll; PbCO3 BP exposure accumulated the most lipid peroxidation products of MDA and H2O2; and PbCO3 NPs triggered the largest cell membrane damage. Furthermore, PbCO3 NPs at 10 and 100 mg·L-1 induced dose-dependent metabolic reprogramming in spinach leaves, disturbing the metabolic mechanisms related to amino acids, antioxidant defense, oxidative phosphorylation, fatty acid cycle, and the respiratory chain. The spinach showed a non-carcinogenic health risk hierarchy: Pb2+ > PbCO3 NPs > PbCO3 BPs, with children more vulnerable than adults. These findings enhance our understanding of PbCO3 particle effects on food security, emphasizing the need for further research to minimize their impact on human dietary health.

Unveiling Innovative Approaches to Mitigate Metals/Metalloids Toxicity for Sustainable Agriculture

Due to anthropogenic activities, environmental pollution of heavy metals/metalloids (HMs) has increased and received growing attention in recent decades. Plants growing in HM-contaminated soils have slower growth and development, resulting in lower agricultural yield. Exposure to HMs leads to the generation of free radicals (oxidative stress), which alters plant morpho-physiological and biochemical pathways at the cellular and tissue levels. Plants have evolved complex defense mechanisms to avoid or tolerate the toxic effects of HMs, including HMs absorption and accumulation in cell organelles, immobilization by forming complexes with organic chelates, extraction via numerous transporters, ion channels, signaling cascades, and transcription elements, among others. Nonetheless, these internal defensive mechanisms are insufficient to overcome HMs toxicity. Therefore, unveiling HMs adaptation and tolerance mechanisms is necessary for sustainable agriculture. Recent breakthroughs in cutting-edge approaches such as phytohormone and gasotransmitters application, nanotechnology, omics, and genetic engineering tools have identified molecular regulators linked to HMs tolerance, which may be applied to generate HMs-tolerant future plants. This review summarizes numerous systems that plants have adapted to resist HMs toxicity, such as physiological, biochemical, and molecular responses. Diverse adaptation strategies have also been comprehensively presented to advance plant resilience to HMs toxicity that could enable sustainable agricultural production.

Combined interactions of amino acids and organic acids in heavy metal binding in plants

This research focused on the different approaches to the transport and internal chelation of metals with amino acids and organic acids in plants. Therefore, in the first phase, the plants studied were identified the characteristics of the bioaccumulation factors. Steria pumila, Echium angustifolium, Typha angustifolia, Sisymbrium austriacum were identified as hyperaccumulators (Cd, Ni), accumulators (Pb, Sn, and Se), excluders (Cr, Hg). On the other hand, the Sisymbrium austriacum only showed the characteristic of the accumulator for Cr. In the second phase, the combined effects of amino acids and organic acids on the chelation of heavy metals in plants were tested by a multi-linear regression model. Related to our hypothesis, Amino acids; Gly and Leu (Cd), Trp and Ile (Pb), Asp, Ser, and Leu (Cr), Ser (Hg), Trp and Glu (Ni), Asp, Thr, and Gly (Sn), Asn and Leu (Se), Organic acids; Malonic and Malic acid (Cd), Malonic acid (Pb), Oxalic and Malic acid (Cr), Oxalic, Succinic, Citric and Butyric acid (Hg), Malonic and Malic acid (Ni), Malonic, Maleic, and Malic acid (Sn), Malonic and Citric acid (Se) were concluded that had combined effect for heavy metal's phytochelation ability into plants.

Toxic effects of lead on plants: integrating multi-omics with bioinformatics to develop Pb-tolerant crops

MAIN CONCLUSION

Lead disrupts plant metabolic homeostasis and key structural elements. Utilizing modern biotechnology tools, it's feasible to develop Pb-tolerant varieties by discovering biological players regulating plant metabolic pathways under stress. Lead (Pb) has been used for a variety of purposes since antiquity despite its toxic nature. After arsenic, lead is the most hazardous heavy metal without any known beneficial role in the biological system. It is a crucial inorganic pollutant that affects plant biochemical and morpho-physiological attributes. Lead toxicity harms plants throughout their life cycle and the extent of damage depends on the concentration and duration of exposure. Higher levels of lead exposure disrupt numerous key metabolic activities of plants including oxygen-evolving complex, organelles integrity, photosystem II connectivity, and electron transport chain. This review summarizes the detrimental effects of lead toxicity on seed germination, crop growth, and yield, oxidative and ultra-structural alterations, as well as nutrient absorption, transport, and assimilation. Further, it discusses the Pb-induced toxic modulation of stomatal conductance, photosynthesis, respiration, metabolic-enzymatic activity, osmolytes accumulation, and antioxidant activity. It is a comprehensive review that reports on omics-based studies along with morpho-physiological and biochemical modifications caused by lead stress. With advances in DNA sequencing technologies, genomics and transcriptomics are gradually becoming popular for studying Pb stress effects in plants. Proteomics and metabolomics are still underrated and there is a scarcity of published data, and this review highlights both their technical and research gaps. Besides, there is also a discussion on how the integration of omics with bioinformatics and the use of the latest biotechnological tools can aid in developing Pb-tolerant crops. The review concludes with core challenges and research directions that need to be addressed soon.

Gibberellic acid 3 enhanced the anticancer activity of Abeliophyllum distichum adventitious roots by activating the diterpenoid biosynthesis pathway

The industrial value of various plants has been improved through the of plant cell culture systems with elicitation. In this study, the adventitious root of Abeliophyllum distichum (AdAR) was treated with gibberellic acid 3 (GA3) to improve its anticancer property. The hexane fraction of the GA3-treated A. distichum adventitious root exhibited a stronger cytotoxic activity against A549 cells than the hexane fraction of AdAR. Through GC/MS and principal component analysis, we identified ferruginol and sugiol as anticancer compounds, which were induced by GA3 treatment in AdAR. Gene expression analysis combined with functional characterisation suggests that the GA3 treatment increased the transcription of geranylgeranyl pyrophosphate synthases and copalyl diphosphate synthase, which led to the accumulation of diterpenoids, including ferruginol and sugiol. Overall, these findings can contribute to the advancement of metabolic engineering for enhancing the biosynthesis of active diterpenoids, and facilitate the large-scale production of bioactive compounds sourced from A. distichum.

Metabolic Adjustment of High Intertidal Alga Pelvetia canaliculata to the Tidal Cycle Includes Oscillations of Soluble Carbohydrates, Phlorotannins, and Citric Acid Content

The brown alga Pelvetia canaliculata is one of the species successfully adapted to intertidal conditions. Inhabiting the high intertidal zone, Pelvetia spends most of its life exposed to air, where it is subjected to desiccation, light, and temperature stresses. However, the physiological and biochemical mechanisms allowing this alga to tolerate such extreme conditions are still largely unknown. The objective of our study is to compare the biochemical composition of Pelvetia during the different phases of the tidal cycle. To our knowledge, this study is the first attempt to draft a detailed biochemical network underneath the complex physiological processes, conferring the successful survival of this organism in the harsh conditions of the high intertidal zone of the polar seas. We considered the tide-induced changes in relative water content, stress markers, titratable acidity, pigment, and phlorotannin content, as well as the low molecular weight metabolite profiles (GC-MS-based approach) in Pelvetia thalli. Thallus desiccation was not accompanied by considerable increase in reactive oxygen species content. Metabolic adjustment of P. canaliculata to emersion included accumulation of soluble carbohydrates, various phenolic compounds, including intracellular phlorotannins, and fatty acids. Changes in titratable acidity accompanied by the oscillations of citric acid content imply that some processes related to the crassulacean acid metabolism (CAM) may be involved in Pelvetia adaptation to the tidal cycle.

Metabolomic analysis reveals the molecular responses to copper toxicity in rice (Oryza sativa)

Copper (Cu) is one of the essential microelements and widely participates in various pathways in plants, but excess Cu in plant cells could induce oxidative stress and harm plant growth. Rice (Oryza sativa) is a main crop food worldwide. The molecular mechanisms of rice in response to copper toxicity are still not well understood. In this study, two-week-old seedlings of the rice cultivar Nipponbare were treated with 100 μM Cu²⁺ (CuSO₄) in the external solution for 10 days. Physiological analysis showed that excess Cu significantly inhibited the growth and biomass of rice seedlings. After Cu treatment, the contents of Mn and Zn were significantly reduced in the roots and shoots, while the Fe content was significantly increased in the roots. Meanwhile, the activities of antioxidant enzymes including SOD and POD were dramatically enhanced after Cu treatment. Based on metabolomic analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods, 695 metabolites were identified in rice roots. Among these metabolites, 123 metabolites were up-regulated and 297 were down-regulated, respectively. The differential metabolites (DMs) include carboxylic acids and derivatives, benzene and substituted derivatives, carbonyl compounds, cinnamic acids and derivatives, fatty acyls and organ nitrogen compounds. KEGG analysis showed that these DMs were mainly enriched in TCA cycle, purine metabolism and starch and sucrose metabolism pathways. Many intermediates in the TCA cycle and purine metabolism were down-regulated, indicating a perturbed carbohydrate and nucleic acid metabolism. Taken together, the present study provides new insights into the mechanism of rice roots to Cu toxicity.

Comparative metabolomics of root-tips reveals distinct metabolic pathways conferring drought tolerance in contrasting genotypes of rice

Background

The mechanisms underlying rice root responses to drought during the early developmental stages are yet unknown.

Results

This study aimed to determine metabolic differences in IR64, a shallow-rooting, drought-susceptible genotype, and Azucena, a drought-tolerant and deep-rooting genotype under drought stress. The morphological evaluation revealed that Azucena might evade water stress by increasing the lateral root system growth, the root surface area, and length to access water. At the same time, IR64 may rely mainly on cell wall thickening to tolerate stress. Furthermore, significant differences were observed in 49 metabolites in IR64 and 80 metabolites in Azucena, for which most metabolites were implicated in secondary metabolism, amino acid metabolism, nucleotide acid metabolism and sugar and sugar alcohol metabolism. Among these metabolites, a significant positive correlation was found between allantoin, galactaric acid, gluconic acid, glucose, and drought tolerance. These metabolites may serve as markers of drought tolerance in genotype screening programs. Based on corresponding biological pathways analysis of the differentially abundant metabolites (DAMs), biosynthesis of alkaloid-derivatives of the shikimate pathway, fatty acid biosynthesis, purine metabolism, TCA cycle and amino acid biosynthesis were the most statistically enriched biological pathway in Azucena in drought response. However, in IR64, the differentially abundant metabolites of starch and sucrose metabolism were the most statistically enriched biological pathways.

Conclusion

Metabolic marker candidates for drought tolerance were identified in both genotypes. Thus, these markers that were experimentally determined in distinct metabolic pathways can be used for the development or selection of drought-tolerant rice genotypes.

Fulvic acid mitigates cadmium toxicity-induced damage in cucumber seedlings through the coordinated interaction of antioxidant enzymes, organic acid, and amino acid

Fulvic acid (FA) can significantly alleviate cadmium (Cd) stress, but the specific metabolic response of FA to Cd toxicity is still not clarified. In the present study, we used untargeted metabolomic [gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS)] analysis to profile cucumber metabolism in response to Cd stress after spray application of FA. Our results showed that 331 differentially enriched metabolites (DEMs) were identified in leaf materials. These DEMs were enriched in 21 shared pathways in comparative groups of "Cd treatment vs. the control treatment" and "FA + Cd treatment vs. the Cd treatment." Specifically, treatment with FA significantly enhanced the organic acid content (citric acid, isocitric acid, 2-oxoglutaric acid, fumaric acid, and malic acid), which would contribute to provide sufficient substrates for the tricarboxylic acid (TCA) cycle and amino acid biosynthesis, thereby ensuring the normal production of energy and amino acid. At the same time, FA significantly increased the amino acid content (aspartate, citrulline, histidine, leucine, and phenylalanine). The accumulation of organic acid and amino acid can act as chelating agents for heavy metal ions and as scavengers of reactive oxygen species (ROS), thereby reducing intracellular oxidative damage. Furthermore, the application of FA improves antioxidant enzymes and accelerates ROS clearance. The improved contents of organic acid and amino acid, and the increased activity of antioxidant enzymes both played a central role in the reduction of malondialdehyde (MDA, 14.08%), hydrogen peroxide (H₂O₂, 61.70%) contents, and superoxide anion radical (O₂^-, 30.41%) production rate in plants under Cd stress. Taken together, the present study demonstrates the effects of FA on the antioxidant capacity and carbohydrate and amino acid metabolism of cucumber seedlings exposed to Cd stress, which provides comprehensive insights into the regulation of plants' response to Cd toxicity with FA was applied in cucumber.

Photosynthesis-related physiology and metabolomics responses of Polygonum lapathifolium in contrasting manganese environments

Manganese (Mn) plays an essential role in plant growth; however, excessive Mn is toxic to plants. Polygonum lapathifolium Linn. was tested as a novel Mn-hyperaccumulating species in our previous study, but the underlying mechanisms of this hyperaccumulation are poorly understood. A hydroponic experiment with (8mmolL-1 ) and without additional Mn (CK) was established to explore the possible mechanisms through the effects on photosynthesis-related physiological characteristics and metabolomics. The results showed that additional Mn increased plant biomass, photosynthesis, and stomatal conductance related to increases in the effective photochemical quantum yield of photosystem II and relative electron transport rate (P <0.05). The results from liquid chromatography-mass spectrometry revealed 56 metabolites differentially accumulated between the plants composing these two groups. Metabolites were enriched in 20 metabolic pathways at three levels (environmental information processing, genetic information processing, and metabolism), of which five metabolic pathways were associated with significant or extremely significant changes (P <0.05). These five enriched pathways were ABC transporters (environmental information processing), aminoacyl-tRNA biosynthesis (genetic information processing), biosynthesis of amino acids , d -arginine and d -ornithine metabolism , and arginine biosynthesis (metabolism). Flavonoids may play a key role in Mn tolerance, as they accumulated more than 490-fold, and the relationship between flavonoids and Mn tolerance needs to be studied in the future.

Short-Term Effects of Trans-Cinnamic Acid on the Metabolism of Zea mays L. Roots

trans-Cinnamic acid is a phenolic compound widely studied in plant metabolism due to its importance in regulating different plant processes. Previous studies on maize plants showed that this compound could affect plant growth and causes metabolic changes in the leaves when applied. However, its effects on root metabolism are not well known. This study analyses the short-term effect of trans-cinnamic acid on the morphology of vascular bundle elements and metabolism in maize roots. At short times (between 6 and 12 h), there is a reduction in the content of many amino acids which may be associated with the altered nitrogen uptake observed in earlier work. In addition, the compound caused an alteration of the vascular bundles at 48 h and seemed to have changed the metabolism in roots to favor lignin and galactose synthesis. The results obtained complement those previously carried out on maize plants, demonstrating that in the short term trans-cinnamic acid can trigger stress-coping processes in the treated plants.

Cadmium/lead tolerance of six Dianthus species and detoxification mechanism in Dianthus spiculifolius

Toxic heavy metal contaminants seriously affect plant growth and human health. Reducing the accumulation of toxic metals by phytoremediation is an effective way to solve this environmental problem. Dianthus spiculifolius Schur is an ornamental plant with strong cold and drought tolerance. Because of its fast growth, well-developed root system, and large accumulation of biomass, D. spiculifolius has potential applications as a heavy metal hyperaccumulator. Therefore, the aim of this study was evaluate the ability of D. spiculifolius and other Dianthus species to remediate heavy metals, with an ultimate goal to identify available genetic resources for toxic metal removal. The cadmium (Cd) and lead (Pb) tolerance and accumulation of six Dianthus species were analyzed comparatively in physiological and biochemical experiments. Compared with the other Dianthus species, D. spiculifolius showed higher tolerance to, and greater accumulation of, Cd and Pb. Second-generation transcriptome analysis indicated that glutathione transferase activity was increased and the glutathione metabolism pathway was enriched with genes encoding antioxidant enzymes (DsGST, DsGST3, DsGSTU10, DsGGCT2-1, and DsIDH-2) that were up-regulated under Cd/Pb treatment by RT-qPCR in D. spiculifolius. When expressed in yeast, DsGST, DsGST3, DsGSTU10 and DsIDH-2 enhanced Cd or Pb tolerance. These results indicate that D. spiculifolius has potential applications as a new ornamental hyperaccumulator plant, and that antioxidant enzymes might be involved in regulating Cd/Pb accumulation and detoxification. The findings of this study reveal some novel genetic resources that can be used to breed new plant varieties that tolerate and accumulate heavy metals.

Study of FA12 peptide-modified PEGylated liposomal doxorubicin (PLD) as an effective ligand to target Muc1 in mice bearing C26 colon carcinoma: in silico, in vitro, and in vivo study

OBJECTIVES

This study tried to achieve active targeting of Muc1 in cancer; the surface of PEGylated liposomal doxorubicin (PLD/Doxil®) was decorated with FA12 peptide.

METHODS

According to docking results, FA12 was selected for this study, among four different peptides. MD simulation was also conducted as an additional confirmation of the binding interaction between FA12 and Muc1. Liposomal formulations were prepared; ¹HNMR and HPLC techniques were used to verify peptide conjugation to DSPE-PEG2000-COOH. Afterward, DSPE-PEG2000-FA12 was post-inserted into the PLD at 50, 100, 200, and 400 peptides per liposome. The size, zeta potential, release profile, cytotoxicity (IC₅₀), and cell uptake (using fluorescence microscopy and flow cytometry) were evaluated. In vivo biodistribution and antitumor activities were studied on mice bearing C-26 colon carcinoma.

RESULTS

Cell uptake and cytotoxicity results revealed that PLD-100 (targeted PLD with 100 FA12 per liposome) could significantly enhance cellular binding. Furthermore, PLD-100 demonstrated higher antitumor efficacy, indicating more remarkable survival compared to PLD and other targeted PLDs. PLD-100 exhibited higher doxorubicin tumor accumulation compared to PLD.

CONCLUSIONS

FA12 peptide is a promising targeting ligand for PLD to treat cancers with a high level of Muc1 expression and merits further investigations.

Cotton straw biochar and compound Bacillus biofertilizer reduce Cd stress on cotton root growth by regulating root exudates and antioxidant enzymes system

INTRODUCTION

Cotton straw biochar (biochar) and compound Bacillus biofertilizer (biofertilizer) have attracted wide attentions in the remediation of heavy metal-contaminated soils in recent years. However, few studies have explored the metabolomics of lateral roots of Cd-stressed cotton to determine the mechanism of biochar and biofertilizer alleviating Cd stress.

METHODS

In this pot experiment, biochar and biofertilizer were applied to the soils with different Cd contamination levels (1, 2, and 4 mg kg^-1). Then, the responses of cotton root morphology, vitality, Cd content, and antioxidant enzyme activities were analyzed, and the mechanism of biochar and biofertilizer alleviating Cd stress was determined by metabolomic analysis.

RESULTS

The results showed that exogenous Cd addition decreased the SOD and POD activities in cotton taproot and lateral root. Besides, with the increase of soil Cd content, the maximum Cd content in taproot (0.0250 mg kg^-1) and lateral root (0.0288 mg kg^-1) increased by 89.11% and 33.95%, respectively compared with those in the control (p< 0.05). After the application of biochar and biofertilizer, the SOD and POD activities in cotton taproot and lateral root increased. The Cd content of cotton taproot in biochar and biofertilizer treatments decreased by 16.36% and 19.73%, respectively, and that of lateral root decreased by 13.99% and 16.68%, respectively. The metabolomic analysis results showed that the application of biochar and biofertilizer could improve the resistance of cotton root to Cd stress through regulating the pathways of ABC transporters and phenylalanine metabolism.

DISCUSSION

Therefore, the application of biochar and biofertilizer could improve cotton resistance to Cd stress by increasing antioxidant enzyme activities, regulating root metabolites (phenols and amino acids), and reducing Cd content, thus promoting cotton root growth.

Metabolites produced by inoculated Vigna radiata during bacterial assisted phytoremediation of Pb, Ni and Cr polluted soil

Phytoremediation assisted with plant growth promoting bacteria (PGPB) is a green technology to remediate metal contaminated soils. Plants usually produce secondary metabolites to tolerate metal toxicity. Present study was designed to explore the phytoremediation potential of Vigna radiata var. NM-II in the presence of metal resistant PGPB and comparison of metabolites produced under heavy metal stresses (Pb, Ni, Cr). Three PGPB selected for present study include Bacillus pumilus MB246, Serratia nematodiphila MB307 and Delftia Lacustris MB322. Pot experiments were conducted with inoculated V. radiata NM-II seeds grown in soil artificially contaminated with lead (Pb), Nickle (Ni) and chromium (Cr) at a concentration of 300, 200 and 100 mg/kg respectively. After harvesting various growth parameters were studied (root length, shoot length, fresh weight and dry weight). Bacterial colonization on root surfaces of harvested plants was observed through Scanning electron microscopy (SEM) and Elemental composition was recorded through Energy dispersive X-ray spectroscopy (EDX) attached with SEM. Metabolic response of harvested plants was studied through Gas chromatography Mass spectrophotometry (GC-MS) analysis. Metal accumulation in roots, shoots and soil was analysed by acid digestion method from which Bioaccumulation factor (BF) and Translocation factor (TF) of metal from soil to plant was calculated. Results revealed stimulatory effect of PGPB on growth and phytoextraction ability of V. radiata. Soil metal removal efficiency was in the order Pb>Ni>Cr, whereas metal distribution in each part of plant was root>stem>leaf. The BF and TF values suggested V. radiata as Pb and Ni excluder while moderate accumulator for Cr. Elemental analysis through Energy Dispersive X- ray spectroscopy (EDX) found potassium (K+)and calcium (Ca+)as highly abundant nutrients with least accumulation of sulphur (S). Metabolites study through GC-MS revealed variety of compounds (carbohydrates, amino acids, fatty acids, steroids etc) detected differentially under each metal treatment and their concentration was influenced by different bacterial inoculations. Overall 9-Octadecenamide was found as commonly present lipid compound in most of the treatments which is required for detoxification in plants. The study concluded beneficial role of PGPB for successful phytoremediation of heavy metals and differential response of metabolites towards each metal stress that is related to metal tolerance ability of V. radiata.

Pseudomonas citronellolis alleviates arsenic toxicity and maintains cellular homeostasis in chickpea (Cicer arietinum L.)

Arsenic is a hazardous metalloid that causes detrimental effects on plant growth and metabolism. Plants accumulate arsenic in edible parts that consequently enter the food chain leading to many health problems. Metal tolerant plant growth-promoting bacteria (PGPB) ameliorate heavy metal toxicity. In this study, the effect of arsenic (As⁵⁺) and the role of PGPB Pseudomonas citronellolis (PC) in mitigating As⁵⁺ toxicity and associated metabolic alterations in chickpea were assessed. Five chickpea varieties (PBG1, GPF2, PDG3, PDG4 and PBG5) were evaluated for arsenic accumulation, translocation, and its interference with metabolic and defense processes. As⁵⁺ (40 mg kg^-1) interfered with plant metabolism and enhanced the antioxidative and carbohydrate metabolizing enzyme's activity but PC treatment maintained the activity at par with control. PC also facilitated the accumulation of As⁵⁺ in the root system and restricted its translocation to the shoot. Further, to map the metabolic changes, Gas chromatography Mass Spectroscopy (GC-MS) based metabolite profiling and gene expression analysis (qRT-PCR) were performed in the best and worst-performing chickpea varieties (PBG1 and PBG5). 48 metabolites of various metabolic pathways (amino acid, carbohydrate, and fatty acid) were altered in As⁵⁺ and PC treatment. Gene expressions showed correlation with biochemical analysis of the antioxidative enzymes and carbohydrate metabolizing enzymes while PC treatment improved chlorophyll biosynthesis enzyme CaDALA expression in As⁵⁺ treated plants. Therefore, PC mitigates As⁵⁺ toxicity by restricting it in the roots thereby maintaining the cellular homeostasis under As⁵⁺ stress in chickpeas.

Untargeted LC-MS/MS-Based Metabolomic Profiling for the Edible and Medicinal Plant Salvia miltiorrhiza Under Different Levels of Cadmium Stress

Salvia miltiorrhiza, a medicinal and edible plant, has been extensively applied to treat cardiovascular diseases and chronic hepatitis. Cadmium (Cd) affects the quality of S. miltiorrhiza, posing serious threats to human health. To reveal the metabolic mechanisms of S. miltiorrhiza's resistance to Cd stress, metabolite changes in S. miltiorrhiza roots treated with 0 (CK), 25 (T1), 50 (T2) and 100 (T3) mg kg-1 Cd by liquid chromatography coupled to mass spectrometry (LC-MS/MS) were investigated. A total of 305 metabolites were identified, and most of them were amino acids, organic acids and fatty acids, which contributed to the discrimination of CK from the Cd-treated groups. Among them, S. miltiorrhiza mainly upregulated o-tyrosine, chorismate and eudesmic acid in resistance to 25 mg kg-1 Cd; DL-tryptophan, L-aspartic acid, L-proline and chorismite in resistance to 50 mg kg-1 Cd; and L-proline, L-serine, L-histidine, eudesmic acid, and rosmarinic acid in resistance to 100 mg kg-1 Cd. It mainly downregulated unsaturated fatty acids (e.g., oleic acid, linoleic acid) in resistance to 25, 50, and 100 mg kg-1 Cd and upregulated saturated fatty acids (especially stearic acid) in resistance to 100 mg kg-1 Cd. Biosynthesis of unsaturated fatty acids, isoquinoline alkaloid, betalain, aminoacyl-tRNA, and tyrosine metabolism were the significantly enriched metabolic pathways and the most important pathways involved in the Cd resistance of S. miltiorrhiza. These data elucidated the crucial metabolic mechanisms involved in S. miltiorrhiza Cd resistance and the crucial metabolites that could be used to improve resistance to Cd stress in medicinal plant breeding.

A review on bioremediation approach for heavy metal detoxification and accumulation in plants

Nowadays, the accumulation of toxic heavy metals in soil and water streams is considered a serious environmental problem that causes various harmful effects on plants and animals. Phytoremediation is an effective, green, and economical bioremediation approach by which the harmful heavy metals in the contaminated ecosystem can be detoxified and accumulated in the plant. Hyperaccumulators exude molecules called transporters that carry and translocate the heavy metals present in the soil to different plant parts. The hyperaccumulator plant genes can confine higher concentrations of toxic heavy metals in their tissues. The efficiency of phytoremediation relies on various parameters such as soil properties (pH and soil type), organic matters in soil, heavy metal type, nature of rhizosphere, characteristics of rhizosphere microflora, etc. The present review comprehensively discusses the toxicity effect of heavy metals on the environment and different phytoremediation mechanisms for the transport and accumulation of heavy metals from polluted soil. This review gave comprehensive insights into plants tolerance for the higher heavy metal concentration their responses for heavy metal accumulation and the different mechanisms involved for heavy metal tolerance. The current status and the characteristic features that need to be improved in the phytoremediation process are also reviewed in detail.

Metabolite profiling of Bruguiera cylindrica reveals presence of potential bioactive compounds

Bruguiera cylindrica parts are commonly used in Chinese and Indian traditional medicine to treat diarrhea, fever, and many ailments. The present study aims non targeted analysis of key secondary metabolites of B. cylindrica by gas chromatography mass spectrometry (GC-MS) and ultra-high performance liquid chromatography hybrid quadrupole-Exactive-Orbitrap high resolution mass spectrometry (UHPLC-Q-Exactive Orbitrap HRMS). GC-MS and UHPLC-Q-Exactive Orbitrap HRMS were utilized for metabolic profiling of ethyl acetate extract of B. cylindrica leaves. Key metabolites in the extract were identified and predicted based on chemical similarity using online databases such as ChemSpider and mzCloud. Thirty-six compounds belonging to different classes of secondary metabolites viz. flavonoids, fatty acids, fatty acid amides, carboxylic acids, and alkaloids were identified in the extract. Pentacyclic triterpenes like betulin, ursolic acid and a tropine, an alkaloid with potential pharmacological and therapeutic activities such as anticancer properties, neuromuscular blockers and antioxidants, were also identified. This study combined GC-MS and UHPLC-Q-Exactive Orbitrap HRMS with available online database for effective and rapid identification of bioactive metabolites in the ethyl acetate extract of mangrove without individual standard application. This is the first report on the HRMS based secondary metabolic profiling of B. cylindrica, with comprehensive map of its biologically important metabolites.

Salinity mediated cross-tolerance of arsenic toxicity in the halophyte Salvadora persica L. through metabolomic dynamics and regulation of stomatal movement and photosynthesis

Arsenic (As) is a highly toxic metalloid adversely affecting the environment, human health, and crop productivity. The present study assessed the synergistic effects of salinity and As on photosynthetic attributes, stomatal regulations, and metabolomics responses of the xero-halophyte Salvadora persica to decipher the As-salinity cross-tolerance mechanisms and to identify the potential metabolites/metabolic pathways involved in cross-tolerance of As with salinity. Salinity and As stress-induced significant stomatal closure in S. persica suggests an adaptive response to decrease water loss through transpiration. NaCl supplementation improved the net photosynthetic rate (by +39%), stomatal conductance (by +190%), water use efficiency (by +55%), photochemical quenching (by +37%), and electron transfer rate (54%) under As stress as compared to solitary As treatment. Our results imply that both stomatal and non-stomatal factors account for a reduction in photosynthesis under high salinity and As stress conditions. A total of 64 metabolites were identified in S. persica under salinity and/or As stress, and up-regulation of various metabolites support early As-salinity stress tolerance in S. persica by improving antioxidative defense and ROS detoxification. The primary metabolites such as polyphenols (caffeic acid, catechin, gallic acid, coumaric acid, rosmarinic acid, and cinnamic acid), amino acids (glutamic acid, cysteine, glycine, lysine, phenylalanine, and tyrosine), citrate cycle intermediates (malic acid, oxalic acid, and α-ketoglutaric acid), and most of the phytohormones accumulated at higher levels under combined treatment of As + NaCl compared to solitary treatment of As. Moreover, exogenous salinity increased glutamate, glycine, and cysteine, which may induce higher synthesis of GSH-PCs in S. persica. The metabolic pathways that were significantly affected in response to salinity and/or As include inositol phosphate metabolism, citrate cycle, glyoxylate and dicarboxylate metabolism, amino acid metabolism, and glutathione metabolism. Our findings indicate that inflections of various metabolites and metabolic pathways facilitate S. persica to withstand and grow optimally even under high salinity and As conditions. Moreover, the addition of salt enhanced the arsenic tolerance proficiency of this halophyte.

Physiological defense and metabolic strategy of Pistia stratiotes in response to zinc-cadmium co-pollution

Pistia stratiotes is a cadmium (Cd) hyperaccumulating plant with strong bioaccumulation and translocation capacity for Cd. A hydroponic experiment was used to evaluate the combined effect of Zinc (Zn) and Cd at different concentrations on leaf growth and metabolism of P. stratiotes. This study revealed the physiological defense and metabolic strategy of responses to Zn-Cd co-pollution. With the Zn₅₀Cd₁, Zn₅₀Cd₁₀, Zn₁₀₀Cd_1, and Zn₁₀₀Cd₁₀ treatments for 9 d, the relative crown diameter, relative leave number, and ramet number of the plant had no significant difference with the control. Under the compound treatments containing Zn₅₀Cd₅₀ and Zn₁₀₀Cd₅₀, the activity of the glyoxalase system and amino acid metabolism in the leaves were inhibited. The leaf photosynthetic apparatus increased heat dissipation to reduce the damage to the photosystem II (PS II) reaction center caused by excess excitation energy under Zn-Cd stress. This safeguarded the balance between the absorption and utilization of light energy. Compared to the control, the Zn and Cd co-pollution for 9 d had no effect on the reduced glutathione (GSH) and oxidized glutathione (GSSG) contents. There was no effect on the dehydroascorbate reductase (DHAR) and glutathione reductase (GR) activities, but there was increased ascorbate peroxidase (APX) activity and oxidized ascorbic acid (DHA) content. These increased the antioxidant capacity of the ascorbate-glutathione (AsA-GSH) cycle. The treated plants also had increased levels of carnosol and substances related to lipid metabolism including 9, 10-Dihydroxystearate, Prostaglandin G2, Sphingosine, and 13-L-Hydroperoxylinoleic acid, maintaining the cell stability and resistance to the Zn-Cd stress.

Physiology and metabonomics reveal differences in drought resistance among soybean varieties

BACKGROUND

The soybean is an important food crop worldwide. Drought during the first pod stage significantly affects soybean yield, and understanding the metabolomic and physiological changes in soybeans under drought stress is crucial. This study identified the differential metabolites in initial pod stage soybean leaves under polyethylene glycol-simulated drought stress, using ultra performance liquid chromatography and tandem mass spectrometry, and the physiological indexes related to drought resistance.

RESULTS

Physiologically, drought resistance also generates enzyme and antioxidant activity; levels of superoxide dismutase, peroxidase, and catalase first increased and subsequently decreased, while those of soluble sugar, soluble protein, malondialdehyde, and proline content increased in both varieties. The contents of CAT, proline and soluble sugar in Heinong 44 (HN44) were higher than those in Heinong 65 (HN65), and the contents of MDA were lower than those in HN65. In metabolomics, the OPLS-DA model was used to screen different metabolites. KEGG analysis showed that the two varieties resisted drought through different ways. Amino acid metabolism and lipid metabolism play a key role in drought resistance of the two varieties, respectively. TCA cycle was one of the core pathways of drought resistance in two varieties. Changes in the content of L-Asparagine and citric acid may be one of the reasons for the difference in drought resistance between the two varieties.

CONCLUSIONS

We think that the reasons of drought resistance among soybean varieties are as follows: the main metabolic pathways are different under drought stress; the contents of metabolites in these metabolic pathways are different; some physiological indexes are different, such as MDA, CAT, proline content and so on. Our study enhances the understanding of the metabolomic soybean drought stress response and provides a reference for soybean drought resistance breeding.

Metabolite Profiles Provide Insights into Underlying Mechanism in Bupleurum (Apiaceae) in Response to Three Levels of Phosphorus Fertilization

Phosphorus (P) deficiency affects plant yield and quality, yet at the same time, excessive phosphorus application does not necessarily promote the growth of plants. How to maintain a balance between biomass accumulation and phosphorus application is a problem. Therefore, the purpose of this research was to explore the relationship between yield and quality of Bupleurum and phosphorus fertilization, based on three phosphorus fertilization levels (20 kg∙ha^-1; 10 kg∙ha^-1; and 0 kg∙ha^-1). We adopted gas chromatography-mass spectrometry to assess the response of primary metabolites of different plant tissues (flowers, main shoots, lateral shoots and roots) to phosphorus fertilization. At the same time, high-performance liquid chromatography was used to quantify saikosaponin A and saikosaponin D, the main active ingredients of Bupleurum. Our research showed that low phosphorus level application has a positive impact on the yield and quality of Bupleurum, especially the above-ground parts increasing the fresh weight of flowers and lateral shoots and the length of main shoots, and moreover, increasing the saikosaponins content in all above-ground parts while decreasing the content in roots which show no significance increase in fresh weight and length. However, high phosphorus level showed a negative impact as it decreases the saikosaponins content significantly in flowers and roots. Furthermore, phosphorus application changed the proportion of saikosaponins, promoting the content of saikosaponin A and inhibiting the content of saikosaponin D in most organs of Bupleurum. Therefore, we can say that high phosphorus application is not preferable to the yield and quality of Bupleurum. To identify the metabolic pathways and special key metabolites, a total of 73 metabolites were discovered, and four differential metabolites-ether, glycerol, chlorogenic and L-rhamnose-were considered to be the key metabolites of Bupleurum's response to phosphorus fertilization. Furthermore, Bupleurum's response to phosphorus fertilization was mainly related to metabolic pathways, such as starch and sucrose metabolism and galactose metabolism. Under the phosphorus level, the content of sugars, organic acids and their derivatives, polyols and their derivatives and alkyl were upregulated in flowers. Furthermore, the contents of compounds in the main shoot and lateral shoots showed the same upward trend, except glycosides and polyols and their derivatives.

Advances in thermal physiology of diving marine mammals: The dual role of peripheral perfusion

The ability to maintain a high core body temperature is a defining characteristic of all mammals, yet their diverse habitats present disparate thermal challenges that have led to specialized adaptations. Marine mammals inhabit a highly conductive environment. Their thermoregulatory capabilities far exceed our own despite having limited avenues of heat transfer. Additionally, marine mammals must balance their thermoregulatory demands with those associated with diving (i.e. oxygen conservation), both of which rely on cardiovascular adjustments. This review presents the progress and novel efforts in investigating marine mammal thermoregulation, with a particular focus on the role of peripheral perfusion. Early studies in marine mammal thermal physiology were primarily performed in the laboratory and provided foundational knowledge through in vivo experiments and ex vivo measurements. However, the ecological relevance of these findings remains unknown because comparable efforts on free-ranging animals have been limited. We demonstrate the utility of biologgers for studying their thermal adaptations in the context in which they evolved. Our preliminary results from freely diving northern elephant seals (Mirounga angustirostris) reveal blubber's dynamic nature and the complex interaction between thermoregulation and the dive response due to the dual role of peripheral perfusion. Further exploring the potential use of biologgers for measuring physiological variables relevant to thermal physiology in other marine mammal species will enhance our understanding of the relative importance of morphology, physiology, and behavior for thermoregulation and overall homeostasis.

Root Metabolite Differences in Two Maize Varieties Under Lead (Pb) Stress

To assess root metabolic differences of maize varieties in their response to lead (Pb) stress, the lead-tolerant variety Huidan No. 4 and the lead-sensitive variety Ludan No. 8 were tested under Pb-free and Pb-stressed conditions. Changes in metabolites were measured using ultra-performance liquid chromatography-mass spectrometry. Pb stress changed the levels of the amino acids proline, glutamine, lysine, and arginine in both varieties, whereas glutamate and phenylalanine levels changed only in Huidan No. 4. Pb stress altered cystine, valine, methionine, and tryptophan levels only in Ludan No. 8. Therefore, the synthesis and decomposition of amino acids may affect the response of maize to Pb stress. The degree of change in differential metabolites for Huidan No. 4 was greater than that for Ludan No. 8. In cell wall subcellular components, increases in superoxide dismutase (SOD), peroxidases (PODs), and Pb concentrations were greater in Huidan No. 4 than in Ludan No. 8. Therefore, the greater Pb tolerance of Huidan No. 4 could be due to better sequestration of Pb in cell walls and more effective removal of reactive oxygen species (ROS) from the plant. The levels of certain metabolites only increased in Ludan No. 8, indicating that Pb-sensitive varieties may use different metabolic pathways to cope with Pb stress. Both varieties showed increased levels of some metabolites related to antioxidant protection and osmotic regulation. This study provides an understanding of maize Pb tolerance mechanisms and a basis for further development of tools for use in maize breeding.

Synergistic Effect between Trichoderma virens and Bacillus velezensis on the Control of Tomato Bacterial Wilt Disease

(1) Background: Ralstonia solanacearum causes tomato bacterial wilt disease, one of the most serious tomato diseases. As the combination of Trichoderma virens (Tvien6) and Bacillus velezensis (X5) was more effective at controlling tomato bacterial wilt disease than a single agent, we investigated the synergistic effect of Tvien6 and X5 in controlling this disease; (2) Methods: The disease incidence, plant heights and weights, relative chlorophyll content (SPAD values), defensive enzymes (PPO, POD, and SOD) activities, and metabolome were estimated among four treatment groups (BR treatment, X5 + R. solanacearum (RS-15); TR treatment, Tvien6+ RS-15; TBR treatment, Tvien6 + X5 + RS-15; and R treatment, RS-15); (3) Results: The R treatment group had the highest disease incidence and lowest plant heights, plant weights, SPAD values, defensive enzyme activities, and D-fructose and D-glucose contents; the TBR treatment group had the lowest disease incidence and highest plant heights, plant weights, SPAD values, defensive enzyme activities, and D-fructose and D-glucose contents; (4) Conclusions: The results revealed that Tvien6 and X5 can both individually promote tomato plant growth, increase leaf chlorophyll content, enhance defensive enzyme activities, and induce the accumulation of D-fructose and D-glucose; however, they were more effective when combined.

Regulatory hubs and strategies for improving heavy metal tolerance in plants: Chemical messengers, omics and genetic engineering

Heavy metal (HM) accumulation in the agricultural soil and its toxicity is a major threat for plant growth and development. HMs disrupt functional integrity of the plants, induces altered phenological and physiological responses and slashes down qualitative crop yield. Chemical messengers such as phytohormones, plant growth regulators and gasotransmitters play a crucial role in regulating plant growth and development under metal toxicity in plants. Understanding the intricate network of these chemical messengers as well as interactions of genes/metabolites/proteins associated with HM toxicity in plants is necessary for deciphering insights into the regulatory circuit involved in HM tolerance. The present review describes (a) the role of chemical messengers in HM-induced toxicity mitigation, (b) possible crosstalk between phytohormones and other signaling cascades involved in plants HM tolerance and (c) the recent advancements in biotechnological interventions including genetic engineering, genome editing and omics approaches to provide a step ahead in making of improved plant against HM toxicities.

Comprehensive transcriptome and metabolome profiling reveal metabolic mechanisms of Nitraria sibirica Pall. to salt stress

Nitraria sibirica Pall., a typical halophyte that can survive under extreme drought conditions and in saline-alkali environments, exhibits strong salt tolerance and environmental adaptability. Understanding the mechanism of molecular and physiological metabolic response to salt stress of plant will better promote the cultivation and use of halophytes. To explore the mechanism of molecular and physiological metabolic of N. sibirica response to salt stress, two-month-old seedlings were treated with 0, 100, and 400 mM NaCl. The results showed that the differentially expressed genes between 100 and 400 mmol L^-1 NaCl and unsalted treatment showed significant enrichment in GO terms such as binding, cell wall, extemal encapsulating structure, extracellular region and nucleotide binding. KEGG enrichment analysis found that NaCl treatment had a significant effect on the metabolic pathways in N. sibirica leaves, which mainly including plant-pathogen interaction, amino acid metabolism of the beta alanine, arginine, proline and glycine metabolism, carbon metabolism of glycolysis, gluconeogenesis, galactose, starch and sucrose metabolism, plant hormone signal transduction and spliceosome. Metabolomics analysis found that the differential metabolites between the unsalted treatment and the NaCl treatment are mainly amino acids (proline, aspartic acid, methionine, etc.), organic acids (oxaloacetic acid, fumaric acid, nicotinic acid, etc.) and polyhydric alcohols (inositol, ribitol, etc.), etc. KEGG annotation and enrichment analysis showed that 100 mmol L^-1 NaCl treatment had a greater effect on the sulfur metabolism, cysteine and methionine metabolism in N. sibirica leaves, while various amino acid metabolism, TCA cycle, photosynthetic carbon fixation and sulfur metabolism and other metabolic pathways have been significantly affected by 400 mmol L^-1 NaCl treatment. Correlation analysis of differential genes in transcriptome and differential metabolites in metabolome have found that the genes of AMY2, BAM1, GPAT3, ASP1, CML38 and RPL4 and the metabolites of L-cysteine, proline, 4-aminobutyric acid and oxaloacetate played an important role in N. sibirica salt tolerance control. This is a further improvement of the salt tolerance mechanism of N. sibirica, and it will provide a theoretical basis and technical support for treatment of saline-alkali soil and the cultivation of halophytes.

Metabolic Profiles of Brassica juncea Roots in Response to Cadmium Stress

Brassica juncea has great application potential in phytoremediation of cadmium (Cd)-contaminated soil because of its excellent Cd accumulating and high biomass. In this study, we compared the effects of Cd under 48 h and 7 d stress in roots of Brassica juncea using metabolite profiling. The results showed that many metabolic pathways and metabolites in Brassica juncea roots were altered significantly in response to Cd stress. We found that significant differences in levels of amino acids, organic acids, carbohydrates, lipids, flavonoids, alkaloids, and indoles were induced by Cd stress at different times, which played a pivotal role in the adaptation of Brassica juncea roots to Cd stress. Meanwhile, Brassica juncea roots could resist 48 h Cd stress by regulating the biosynthesis of amino acids, linoleic acid metabolism, aminoacyl-tRNA biosynthesis, glycerophospholipid metabolism, ABC transporters, arginine biosynthesis, valine, leucine and isoleucine biosynthesis, and alpha-linolenic acid metabolism; however, they regulated alpha-linolenic acid metabolism, glycerophospholipid metabolism, ABC transporters, and linoleic acid metabolism to resist 7 d Cd stress. A metabolomic expedition to the response of Brassica juncea to Cd stress will help to comprehend its tolerance and accumulation mechanisms of Cd.

A Comprehensive Targeted Metabolomics Assay for Crop Plant Sample Analysis

Metabolomics plays an important role in various fields from health to agriculture. However, the comprehensive quantitative metabolomic analysis of plants and plant metabolites has not been widely performed. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)-based plant metabolomics offers the sensitivity and breadth of coverage for both phenotyping and disease diagnosis of plants. Here, we report a high-coverage and quantitative MS-based assay for plant metabolite analysis. The assay detects and quantifies 206 primary and secondary plant metabolites, including many key plant hormones. In total, it measures 28 amino acids and derivatives, 27 organic acids, 20 biogenic amines and derivatives, 40 acylcarnitines, 90 phospholipids and C-6 sugars. All the analysis methods in this assay are based on LC-MS/MS techniques using both positive and negative-mode multiple reaction monitoring (MRM). The recovery rates of spiked plant samples at three different concentration levels (low, medium and high) ranged from 80% to 120%, with satisfactory precision values of less than 20%. This targeted plant metabolomic assay has been successfully applied to the analysis of large numbers of pine and spruce needle samples, canola root samples, as well as cannabis samples. Moreover, the assay was specifically developed in a 96-well plate format, which enables automated, high-throughput sample analysis. This assay has already been used to analyze over 1500 crop plant samples in less than two months.

Metabolomic and phenotypic implications of the application of fertilization products containing microcontaminants in lettuce (Lactuca sativa)

Cultivation practice using organic amendments is plausible to ensure global food security. However, plant abiotic stress due to the presence of metals and organic microcontaminants (OMCs) in fertilization products cannot be overlooked. In this study, we monitored lettuce metabolism and phenotypic response following the application of either sewage sludge (SS), the organic fraction of municipal solid waste, swine manure (SM), chemical fertilizers (CF), or no amendment (C) in a greenhouse facility. The experimental set-up consisted of five treatments with five replicates (25 experimental units randomly distributed). All fertilizers were supplied at the equivalent agronomic total nitrogen dose, but the occurrence of trace metals and/or OMCs was greater in the SS and SM than the rest. Non-target metabolomic analysis (high-resolution mass spectrometry coupled with partial least squares regression) identified more than 300 plant metabolites (amino acids, organic acids, sugar alcohols, and sugars), 55 of which showed significant changes in their relative abundances depending on the type of amendment. Functional analysis indicated that the use of CF or SS increased the levels of metabolites involved in carbohydrate and nitrogen metabolism. Therefore, although SS and SM fertilizers had a greater presence of heavy metals and/or OMCs, our results indicate that they did not induce measurable adverse effects in the lettuce phenotype or metabolism. Metabolic changes between fertilizers (CF and SS vs. C and SM) were mainly due to nitrogen availability.

Metabolomics, a Powerful Tool for Understanding Plant Abiotic Stress

Metabolomics is a technology that generates large amounts of data and contributes to obtaining wide and integral explanations of the biochemical state of a living organism. Plants are continuously affected by abiotic stresses such as water scarcity, high temperatures and high salinity, and metabolomics has the potential for elucidating the response-to-stress mechanisms and develop resistance strategies in affected cultivars. This review describes the characteristics of each of the stages of metabolomic studies in plants and the role of metabolomics in the characterization of the response of various plant species to abiotic stresses.

Investigation of bioactivities of Taxus chinensis, Taxus cuspidata, and Taxus × media by gas chromatography-mass spectrometry

Taxus species have attracted much attention for their potency in cancer treatment. However, investigating the bioactivities of Taxus species is a complex task, due to their diversity, slow growth, and endangered state. The most important Taxus species in China are Taxus chinensis (T. chinensis), Taxus cuspidata (T. cuspidata), and Taxus × media (T. media), which mainly grow in the northeastern region. This article probes deep into the differences among the leaves of T. chinensis, T. cuspidata, and T. media, with the aid of gas chromatography-mass spectrometry (GC-MS). Through GC-MS, 162 compounds were detected in the samples and found to contain 35 bioactive metabolites. On this basis, 20 metabolites with significant bioactivities (antibiotic, antioxidant, anticancer, and antiaging effects) were identified via unsupervised learning of principal component analysis and supervised learning of partial least squares-discriminant analysis. The results show that T. media has the most prominent antibiotic, antioxidant, and anticancer effects, while T. cuspidata has the most diverse and abundant metabolites that slow down aging.

Comparative Analysis of Secondary Metabolites and Metabolic Profiling between Diploid and Tetraploid Morus alba L

We profiled and quantified primary (amine, organic acids, tricarboxylic acid cycle intermediates, amino acids, and carbohydrates) and secondary metabolites (triterpenoids, phenolic acids, carotenoids, flavonoids, and anthocyanins) in the edible parts (leaves and fruits) of the diploid and tetraploid cultivar Morus alba L. 'Cheongil.' Through comprehensive metabolic profiling, the tetraploid mulberry cultivar was able to produce diverse metabolites supported by higher accumulation patterns of primary and secondary metabolites in their edible parts. In particular, the edible parts of the tetraploid showed higher accumulation patterns of most metabolites (amino acids, carbohydrates, carotenoids, and anthocyanins) than the diploid, which was supported by the results of principal component analyses (PCAs) showing a clear separation between the diploid and tetraploid groups. Additionally, this metabolome study comprehensively described the correlation between primary and secondary metabolites in the edible parts of diploid and tetraploid mulberry cultivars and provided information useful for plant breeding strategies to improve metabolite biosynthesis using polyploidy.

Biotechnological strategies for enhancing heavy metal tolerance in neglected and underutilized legume crops: A comprehensive review

Contamination of agricultural land and water by heavy metals due to rapid industrialization and urbanization including various natural processes have become one of the major constraints to crop growth and productivity. Several studies have reported that to counteract heavy metal stress, plants should be able to maneuver various physiological, biochemical and molecular processes to improve their growth and development under heavy metal stress. With the advent of modern biotechnological tools and techniques it is now possible to tailor legume and other plants overexpressing stress-induced genes, transcription factors, proteins, and metabolites that are directly involved in heavy metal stress tolerance. This review provides an in-depth overview of various biotechnological approaches and/or strategies that can be used for enhancing detoxification of the heavy metals by stimulating phytoremediation processes. Synthetic biology tools involved in the engineering of legume and other crop plants against heavy metal stress tolerance are also discussed herewith some pioneering examples where synthetic biology tools that have been used to modify plants for specific traits. Also, CRISPR based genetic engineering of plants, including their role in modulating the expression of several genes/ transcription factors in the improvement of abiotic stress tolerance and phytoremediation ability using knockdown and knockout strategies has also been critically discussed.

Insight Into the Metabolomic Characteristics of Post-Transplant Diabetes Mellitus by the Integrated LC-MS and GC-MS Approach- Preliminary Study

Post-transplantation diabetes mellitus (PTDM) is a common metabolic complication after solid organ transplantation, which not only results in elevated microvascular morbidity, but also seriously impacts graft function and recipient survival. However, its underlying mechanism is not yet fully understood. In this study, an integrated liquid chromatography- mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) based-metabolomics approach was adopted to dissect the metabolic fluctuations and deduce potential mechanism associated with PTDM. 68 adult liver transplant recipients were recruited and classified as 32 PTDM and 36 non-PTDM subjects. PTDM group and non-PTDM group were well matched in gender, age, BMI, family history of diabetes, alcohol drinking history, ICU length of stay and hepatitis B infection. Peripheral blood samples from these recipients were collected and prepared for instrument analysis. Data acquired from LC-MS and GC-MS demonstrated significant metabolome alterations between PTDM and non-PTDM subjects. A total of 30 differential metabolites (15 from LC-MS, 15 from GC-MS) were screened out. PTDM patients, compared with non-PTDM subjects, were characterized with increased levels of L-leucine, L-phenylalanine, LysoPE (16:0), LysoPE (18:0), LysoPC (18:0), taurocholic acid, glycocholic acid, taurochenodeoxycholic acid, tauroursodeoxycholic acid, glycochenodeoxycholic acid, glycoursodeoxycholic acid, etc, and with decreased levels of LysoPC (16:1), LysoPC (18:2), LysoPE (22:6), LysoPC (20:4), etc. Taken collectively, this study demonstrated altered metabolites in patients with PTDM, which would provide support for enhancing mechanism exploration, prediction and treatment of PTDM.

Promoting Human Nutrition and Health through Plant Metabolomics: Current Status and Challenges

Simple Summary

This review summarizes the status, applications, and challenges of plant metabolomics in the context of crop breeding, food quality and safety, and human nutrition and health. It also highlights the importance of plant metabolomics in elucidating biochemical and genetic bases of traits associated with nutritive and healthy beneficial foods and other plant products to secure food supply, to ensure food quality, to protect humans from malnutrition and other diseases. Meanwhile, this review calls for comprehensive collaborations to accelerate relevant researches and applications in the context of human nutrition and health.

Abstract

Plant metabolomics plays important roles in both basic and applied studies regarding all aspects of plant development and stress responses. With the improvement of living standards, people need high quality and safe food supplies. Thus, understanding the pathways involved in the biosynthesis of nutritionally and healthily associated metabolites in plants and the responses to plant-derived biohazards in humans is of equal importance to meet people’s needs. For each, metabolomics has a vital role to play, which is discussed in detail in this review. In addition, the core elements of plant metabolomics are highlighted, researches on metabolomics-based crop improvement for nutrition and safety are summarized, metabolomics studies on plant natural products including traditional Chinese medicine (TCM) for health promotion are briefly presented. Challenges are discussed and future perspectives of metabolomics as one of the most important tools to promote human nutrition and health are proposed.

Long-Term Cd Exposure Alters the Metabolite Profile in Stem Tissue of Medicago sativa

As a common pollutant, cadmium (Cd) is one of the most toxic heavy metals accumulating in agricultural soils through anthropogenic activities. The uptake of Cd by plants is the main entry route into the human food chain, whilst in plants it elicits oxidative stress by unbalancing the cellular redox status. Medicago sativa was subjected to chronic Cd stress for five months. Targeted and untargeted metabolic analyses were performed. Long-term Cd exposure altered the amino acid composition with levels of asparagine, histidine and proline decreasing in stems but increasing in leaves. This suggests tissue-specific metabolic stress responses, which are often not considered in environmental studies focused on leaves. In stem tissue, profiles of secondary metabolites were clearly separated between control and Cd-exposed plants. Fifty-one secondary metabolites were identified that changed significantly upon Cd exposure, of which the majority are (iso)flavonoid conjugates. Cadmium exposure stimulated the phenylpropanoid pathway that led to the accumulation of secondary metabolites in stems rather than cell wall lignification. Those metabolites are antioxidants mitigating oxidative stress and preventing cellular damage. By an adequate adjustment of its metabolic composition, M. sativa reaches a new steady state, which enables the plant to acclimate under chronic Cd stress.

Chemometric techniques coupled with NMR for matabolic profiling of lettuce exposed to polycyclic aromatic hydrocarbones

Treated waste water (TWW) quality varies due to the occurrence of polycyclic aromatic hydrocarbons (PAHs) up to low μg L-1. In this study, a non-targeted metabolomic analysis was performed on lettuce (Lactuca sativa L) exposed to 4 PAHs by irrigation. The plants were watered with different concentrations of contaminants (0-100 μg L-1) for 39 days under controlled conditions and then harvested, extracted and analyzed by nuclear magnetic resonance (NMR). Different chemometric tools based on principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) are proposed for the analysis of the complex data sets generated in the different exposure experiments. Furthermore, Analysis of Variance Simultaneous Component Analysis (ASCA) of changes on metabolite peaks showed significant PAHs concentration and exposure time-dependent changes, clearly differentiating between exposed and non-exposed samples.

Metabolomic Profiling of Drought-Tolerant and Susceptible Peanut (Arachis hypogaea L.) Genotypes in Response to Drought Stress

Peanut is frequently constrained by extreme environmental conditions such as drought. To reveal the involvement of metabolites, TAG 24 (drought-tolerant) and JL 24 (drought-sensitive) peanut genotypes were investigated under control and 20% PEG 6000-mediated water scarcity conditions at the seedling stage. Samples were analyzed by gas chromatography-mass spectrometry (GC-MS) to identify untargeted metabolites and targeted metabolites, i.e., polyamines and polyphenols by high-performance liquid chromatography (HPLC) and ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), respectively. The principal component analysis (PCA), partial least-squares discriminant analysis (PLS-DA), heat map, and cluster analysis were applied to the metabolomics data obtained by the GC-MS technique to determine the important metabolites for drought tolerance. Among 46 resulting metabolites, pentitol, phytol, xylonic acid, d-xylopyranose, stearic acid, and d-ribose were important drought-responsive metabolites. Agmatine and cadaverine were present in TAG 24 leaves and roots, respectively, during water-deficit conditions and believed to be the potential polyamines for drought tolerance. Polyphenols such as syringic acid and vanillic acid were produced more in the leaves of TAG 24, while catechin production was high in JL 24 during stress conditions. Seven metabolic pathways, namely, galactose metabolism, starch and sucrose metabolism, fructose and mannose metabolism, pentose and glucuronate interconversion, propanoate metabolism, amino sugar and nucleotide sugar metabolism, and biosynthesis of unsaturated fatty acids were significantly affected by water-deficit conditions. This study provides valuable information about the metabolic response of peanut to drought stress and metabolites identified, which encourages further study by transcriptome and proteomics to improve drought tolerance in peanut.

Absorption and interaction mechanisms of uranium & cadmium in purple sweet potato(Ipomoea batatas L.)

The purpose of this study was to reveal the absorption and interaction mechanisms of uranium (U) & cadmium (Cd) in corps. Purple sweet potato (Ipomoea batatas L.) was selected as the experimental material. The absorption behavior of U and Cd in this crop and the effects on mineral nutrition were analyzed in a pot experiment. The interactions between U and Cd in purple sweet potato were analyzed using UPLC-MS metabolome analysis. The pot experiment confirmed that the root tuber of the purple sweet potato had accumulated U (1.68-5.16 mg kg^-1) and Cd (0.78-2.02 mg kg^-1) and would pose a health risk if consumed. Both U and Cd significantly interfered with the mineral nutrient of the roots. Metabolomics revealed that a total of 4865 metabolites were identified in roots. 643 (419 up; 224 down), 526 (332 up; 194 down) and 634 (428 up; 214 down) different metabolites (DEMs) were identified in the U, Cd, and U + Cd exposure groups. Metabolic pathway analysis showed that U and Cd induced the expression of plant hormones (the first messengers) and cyclic nucleotides (cAMP and cGMP, second messengers) in cells and regulated the primary/secondary metabolism of roots to induce resistance to U and Cd toxicity.

TiO2 nanoparticles induced sugar impairments and metabolic pathway shift towards amino acid metabolism in wheat

TiO₂-nanoparticles (TiO₂-NP) have the potential to impair plant development. Nevertheless, the metabolic processes behind the physiological responses to TiO₂-NP are still far from being fully understood. In this study, Triticum aestivum plants were exposed for 21 days to different concentrations (0; 5; 50; 150 mg L^-1) of TiO₂-NP (P25). After treatment, the metabolite profiles of roots and leaves were analysed. The content of >70 % of the identified metabolites changed in response to P25 and the impact on metabolic pathways increased with TiO₂-NP dose, with leaves showing higher alterations. Roots up-regulated monosaccharides, azelaic acid, and γ-aminobutanoic acid and triggered the tyrosine metabolism, whereas leaves up-regulated the metabolisms of reserve sugars and tocopherol, and the phenylalanine and tryptophan pathways. Both organs (mainly leaves) up-regulated the aspartate family pathway together with serine, alanine and valine metabolisms and the glycerolipids' biosynthesis. In addition, the citrate and glyoxylate metabolisms were down-regulated in both organs (highest dose). Sugar biosynthesis breakdown, due to photosynthetic disturbances, shifted the cell metabolism to use amino acids as an alternative energy source, and both ROS and sugars worked as signalling molecules activating organ dependent antioxidant responses. Concluding, these NP-pollutants severely impact multiple crop metabolic pathways and may ultimately compromise plant performance.