Metabolomics characterizes the metabolic changes of Lonicerae Japonicae Flos under different salt stresses

Discrimination and characterization of volatile organic compounds in Lonicerae Japonicae flos and Lonicerae flos using multivariate statistics combined with headspace gas chromatography-ion mobility spectrometry and headspace solid-phase microextraction gas chromatography-mass spectrometry techniques

RATIONALE

The volatile organic compounds (VOCs) of Lonicerae Japonicae flos (LJF) and Lonicera flos (LF) play a pivotal role in determining their sensory characteristics, medicinal properties, and subsequent impact on market pricing and consumer preferences. However, the differences and specificity of these VOCs remain obscure. Hence, it is crucial to conduct a comprehensive characterization of the VOCs in LJF and LF and pinpoint their potential differential VOCs.

METHODS

In this study, headspace gas chromatography-ion mobility spectrometry (HS-GC/IMS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) were employed to comprehensively investigate the compositional characteristics and distinctions in VOCs between LJF and LF. Multivariate statistical analysis was used to identify candidate differential VOCs of LJF and LF samples.

RESULTS

A total of 54 and 88 VOCs were identified using HS-GC/IMS and HS-SPME-GC/MS analysis, respectively. Primary VOCs detected in LJF include leaf alcohol, (E)-2-hexen-1-ol dimer, 2-octyn-1-ol, and (E)-3-hexen-1-ol. Key VOCs prevalent in LF encompass farnesol, heptanoic acid, octanoic acid, and valeric acid. Multivariate statistical analysis indicates that compounds such as phenethyl alcohol and leaf alcohol were selected as potential VOCs for distinguishing between LJF and LF.

CONCLUSION

This research conducted a comprehensive analysis of the fundamental volatile components in both LJF and LF. It subsequently elucidated the distinctions and specificities within their respective VOC profiles. And this study enables differentiation between LJF and LF through the analysis of VOCs, offering valuable insights for enhancing the quality control of both LJF and LF.

Metabolomics reveals the response of hydroprimed maize to mitigate the impact of soil salinization

Soil salinization is a major environmental stressor hindering global crop production. Hydropriming has emerged as a promising approach to reduce salt stress and enhance crop yields on salinized land. However, a better mechanisitic understanding is required to improve salt stress tolerance. We used a biochemical and metabolomics approach to study the effect of salt stress of hydroprimed maize to identify the types and variation of differentially accumulated metabolites. Here we show that hydropriming significantly increased catalase (CAT) activity, soluble sugar and proline content, decreased superoxide dismutase (SOD) activity and peroxide (H₂O₂) content. Conversely, hydropriming had no significant effect on POD activity, soluble protein and MDA content under salt stress. The Metabolite analysis indicated that salt stress significantly increased the content of 1278 metabolites and decreased the content of 1044 metabolites. Ethisterone (progesterone) was the most important metabolite produced in the roots of unprimed samples in response to salt s tress. Pathway enrichment analysis indicated that flavone and flavonol biosynthesis, which relate to scavenging reactive oxygen species (ROS), was the most significant metabolic pathway related to salt stress. Hydropriming significantly increased the content of 873 metabolites and significantly decreased the content of 1313 metabolites. 5-Methyltetrahydrofolate, a methyl donor for methionine, was the most important metabolite produced in the roots of hydroprimed samples in response to salt stress. Plant growth regulator, such as melatonin, gibberellin A8, estrone, abscisic acid and brassinolide involved in both treatment. Our results not only verify the roles of key metabolites in resisting salt stress, but also further evidence that flavone and flavonol biosynthesis and plant growth regulator relate to salt tolerance.

Melatonin enhances stress tolerance in pigeon pea by promoting flavonoid enrichment, particularly luteolin in response to salt stress

Melatonin improves plant resistance to multiple stresses by participating in the biosynthesis of metabolites. Flavonoids are an important family of plant secondary metabolites and are widely recognized to be involved in resistance; however, the crosstalk between melatonin and flavonoid is largely unknown. We found that the resistance of pigeon pea (Cajanus cajan) to salt, drought, and heat stresses were significantly enhanced by pre-treatment with melatonin. Combined transcriptome and LC-ESI-MS/MS metabolomics analyses showed that melatonin significantly induced the enrichment of flavonoids and mediated the reprogramming of biosynthetic pathway genes. The highest fold-increase in expression in response to melatonin treatment was observed for the CcF3´H family, which encodes an enzyme that catalyses the biosynthesis of luteolin, and the transcription factor CcPCL1 directly bonded to the CcF3´H-5 promoter to enhance its expression. In addition, salt stress also induced the expression of CcPCL1 and CcF3´H-5, and their overexpression in transgenic plants greatly enhanced salt tolerance by promoting the biosynthesis of luteolin. Overall, our results indicated that pre-treatment of pigeon pea with melatonin promoted luteolin biosynthesis through the CcPCL1 and CcF3´H-5 pathways, resulting in salt tolerance. Our study shows that melatonin enhances plant tolerance to multiple stresses by mediating flavonoid biosynthesis, providing new avenues for studying the crosstalk between melatonin and flavonoids.

Evaluation of metabolites in Iranian Licorice accessions under salinity stress and Azotobacter sp. inoculation

Licorice (Glycyrrhiza glabra L.) is an industrial medicinal plant that is potentially threatened by extinction. In this study, the effects of salinity (0 and 200 mM sodium chloride (NaCl)) and Azotobacter inoculation were evaluated on 16 licorice accessions. The results showed that salinity significantly reduced the fresh and dry biomass (FW and DW, respectively) of roots, compared to plants of the control group (a decrease of 15.92% and 17.26%, respectively). As a result of bacterial inoculation, the total sugar content of roots increased by 21.56% when salinity was applied, but increased by 14.01% without salinity. Salinity stress increased the content of glycyrrhizic acid (GA), phenols, and flavonoids in licorice roots by 104.6%, 117.2%, and 56.3%, respectively. Integrated bacterial inoculation and salt stress significantly increased the GA content in the accessions. Bajgah and Sepidan accessions had the highest GA contents (96.26 and 83.17 mg/g DW, respectively), while Eghlid accession had the lowest (41.98 mg/g DW). With the bacterial application, the maximum amounts of glabridin were obtained in Kashmar and Kermanshah accessions (2.04 and 1.98 mg/g DW, respectively). Bajgah and Kashmar accessions had higher amounts of rutin in their aerial parts (6.11 and 9.48 mg/g DW, respectively) when their roots were uninoculated. In conclusion, these results can assist in selecting promising licorice accessions for cultivation in harsh environments.

Lonicerae Japonicae Flos Attenuates Neutrophilic Inflammation by Inhibiting Oxidative Stress

Lonicerae japonicae flos (LJ) is an Asian traditional herb that is used as a dietary supplement, tea, and beverage to clear heat and quench thirst. However, no studies investigated its effect on activated human neutrophils, which played a crucial role in the bad prognosis of coronavirus disease of 2019 (COVID-19) patients by aggravating lung inflammation and respiratory failure. Herein, we evaluated the anti-inflammatory effect of LJ ethanol extract (LJEE) on human neutrophils activated by N-formyl-methionyl-leucyl-phenylalanine (fMLF). Our experimental results indicated that LJEE suppressed fMLF-activated superoxide anion (O₂^•−) generation, the expression of CD11b, and cell adhesion and migration, as well as the formation of neutrophil extracellular traps in human neutrophils. Further in-depth mechanical investigation revealed that pretreatment with LJEE accelerated the Ca²⁺ clearance, but did not affect the phosphorylation of mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt) in activated human neutrophils. In addition, LJEE displayed a dose-dependent reactive oxygen species (ROS) scavenger activity, which assisted its anti-inflammatory activity. From the bioassay-coupled chromatographic profile, chlorogenic acids were found to dominate the anti-inflammatory effects of LJEE. Moreover, LJ water extract (LJWE) demonstrated an interrupting effect on the severe acute respiratory syndrome coronavirus-2 spike protein (SARS-CoV-2-Spike)/angiotensin-converting enzyme 2 (ACE2) binding. In conclusion, the obtained results not only supported the traditional use of LJ for heat-clearance, but also suggested its potential application in daily health care during the COVID-19 pandemic.

Metabolomics and Chemoinformatics in Agricultural Biotechnology Research: Complementary Probes in Unravelling New Metabolites for Crop Improvement

The United Nations (UN) estimate that the global population will reach 10 billion people by 2050. These projections have placed the agroeconomic industry under immense pressure to meet the growing demand for food and maintain global food security. However, factors associated with climate variability and the emergence of virulent plant pathogens and pests pose a considerable threat to meeting these demands. Advanced crop improvement strategies are required to circumvent the deleterious effects of biotic and abiotic stress and improve yields. Metabolomics is an emerging field in the omics pipeline and systems biology concerned with the quantitative and qualitative analysis of metabolites from a biological specimen under specified conditions. In the past few decades, metabolomics techniques have been extensively used to decipher and describe the metabolic networks associated with plant growth and development and the response and adaptation to biotic and abiotic stress. In recent years, metabolomics technologies, particularly plant metabolomics, have expanded to screening metabolic biomarkers for enhanced performance in yield and stress tolerance for metabolomics-assisted breeding. This review explores the recent advances in the application of metabolomics in agricultural biotechnology for biomarker discovery and the identification of new metabolites for crop improvement. We describe the basic plant metabolomics workflow, the essential analytical techniques, and the power of these combined analytical techniques with chemometrics and chemoinformatics tools. Furthermore, there are mentions of integrated omics systems for metabolomics-assisted breeding and of current applications.

Computational Metabolomics Tools Reveal Metabolic Reconfigurations Underlying the Effects of Biostimulant Seaweed Extracts on Maize Plants under Drought Stress Conditions

Drought is one of the major abiotic stresses causing severe damage and losses in economically important crops worldwide. Drought decreases the plant water status, leading to a disruptive metabolic reprogramming that negatively affects plant growth and yield. Seaweed extract-based biostimulants show potential as a sustainable strategy for improved crop health and stress resilience. However, cellular, biochemical, and molecular mechanisms governing the agronomically observed benefits of the seaweed extracts on plants are still poorly understood. In this study, a liquid chromatography–mass spectrometry-based untargeted metabolomics approach combined with computational metabolomics strategies was applied to unravel the molecular ‘stamps’ that define the effects of seaweed extracts on greenhouse-grown maize (Zea mays) under drought conditions. We applied mass spectral networking, substructure discovery, chemometrics, and metabolic pathway analyses to mine and interpret the generated mass spectral data. The results showed that the application of seaweed extracts induced alterations in the different pathways of primary and secondary metabolism, such as phenylpropanoid, flavonoid biosynthesis, fatty acid metabolism, and amino acids pathways. These metabolic changes involved increasing levels of phenylalanine, tryptophan, coumaroylquinic acid, and linolenic acid metabolites. These metabolic alterations are known to define some of the various biochemical and physiological events that lead to enhanced drought resistance traits. The latter include root growth, alleviation of oxidative stress, improved water, and nutrient uptake. Moreover, this study demonstrates the use of molecular networking in annotating maize metabolome. Furthermore, the results reveal that seaweed extract-based biostimulants induced a remodeling of maize metabolism, subsequently readjusting the plant towards stress alleviation, for example, by increasing the plant height and diameter through foliar application. Such insights add to ongoing efforts in elucidating the modes of action of biostimulants, such as seaweed extracts. Altogether, our study contributes to the fundamental scientific knowledge that is necessary for the development of a biostimulants industry aiming for a sustainable food security.

Polysaccharides and polyphenol in dried Morinda citrifolia fruit tea after different processing conditions: Optimization analysis using response surface methodology

The increasing popularity of Morinda citrifolia has many medical and health benefits because of its rich polysaccharides (PSC) and polyphenols (PPN). It has become popular to brew the dry M. citrifolia fruit slice as tea in some regions of China. In this study, optimize the extraction parameters of M. citrifolia fruit tea polysaccharides and polyphenols using response surface methodology. The results indicated the highest PSC yield of 17% at 46 °C for 11 min and the ratio of water/M. citrifolia fruit powder was 78 mL/g. The optimum extraction of PPN was at 95 °C for 10 min and the ratio of water/M. citrifolia fruit powder 90 mL/g, with 8.93% yield. Using dry M. citrifolia fruit slices as a tea is reported for the first time. Based on the results, the maximum level of PSC can be obtained under condition by infusing about four dried M. citrifolia fruit slice with average thickness and size in warm boiled water for 11 min, taking a 300 mL cup (300 mL of water) for example. The maximum level of PPN can be obtained by adding three slices of dried M. citrifolia fruit slice to boiled water for 10 min. Considering the powder used in our study, the further pulverization of cutting into powder is more conducive to material precipitation. This study provides a scientific basis for obtaining PSC and PPN from dry M. citrifolia fruit slice tea by brewing.

Salinity Stress Alters the Secondary Metabolic Profile of M. sativa, M. arborea and Their Hybrid (Alborea)

Increased soil salinity, and therefore accumulation of ions, is one of the major abiotic stresses of cultivated plants that negatively affect their growth and yield. Among Medicago species, only Medicago truncatula, which is a model plant, has been extensively studied, while research regarding salinity responses of two important forage legumes of Medicago sativa (M. sativa) and Medicago arborea (M. arborea) has been limited. In the present work, differences between M. arborea, M. sativa and their hybrid Alborea were studied regarding growth parameters and metabolomic responses. The entries were subjected to three different treatments: (1) no NaCl application (control plants), (2) continuous application of 100 mM NaCl (acute stress) and (3) gradual application of NaCl at concentrations of 50-75-150 mM by increasing NaCl concentration every 10 days. According to the results, M. arborea maintained steady growth in all three treatments and appeared to be more resistant to salinity. Furthermore, results clearly demonstrated that M. arborea presented a different metabolic profile from that of M. sativa and their hybrid. In general, it was found that under acute and gradual stress, M. sativa overexpressed saponins in the shoots while M. arborea overexpressed saponins in the roots, which is the part of the plant where most of the saponins are produced and overexpressed. Alborea did not perform well, as more metabolites were downregulated than upregulated when subjected to salinity stress. Finally, saponins and hydroxycinnamic acids were key players of increased salinity tolerance.

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.