Physiological, Metabolic, and Transcriptomic Analyses Reveal the Responses of Arabidopsis Seedlings to Carbon Nanohorns

Synergistic singlet oxygen and UV irradiation for efficient intracellular ARGs removal via peroxymonosulfate/catalytic membrane-UV system

The eliminate of antibiotic resistance genes (ARGs) is pivotal in mitigating the proliferation of antibiotic resistance. In this study, a PMS/CM-UV system was engineered, combining a Co3O4-modified carbon nanotubes catalytic membrane with LED-UV lamps, to effectively eliminate intracellular ARGs (iARGs). Leveraging the synergistic effect of singlet oxygen (1O2) and UV irradiation, this process requires only a brief hydraulic retention time of a few minutes and standard UV disinfection irradiation intensity. The cellular physiological function and transcriptomic analysis indicated that reactive oxygen species (ROS) and UV irradiation compromised the cell membrane integrity of E. coli MG1655-SD, as indicated by the down-regulation of the feoB gene, leading to an increased concentration of 1O2 within the intracellular environment. The synergistic effect of 1O2 and UV irradiation resulted in the down-regulation of btuE, thereby curtailing the SOS and oxidative stress responses. Additionally, UV irradiation down-regulated ftsK, uvrB, and uvrA genes, involved in DNA replication, damage site recognition, and self-repair. These processes collectively contribute to the oxidative damage of iARGs by 1O2 before their release into the extracellular environment. This work provided a strategy to develop advanced oxidation disinfection technology aimed at ARGs removal.

Carbon-based nanomaterials as inducers of biocompounds in plants: Potential risks and perspectives

Biocompounds are metabolites synthesized by plants, with clinically proven capacity in preventing and treating degenerative diseases in humans. Carbon-based nanomaterials (CNMs) are atomic structures that assume different hybridization and shape. Due to the reactive property, CNMs can induce the synthesis of metabolites, such as biocompounds in cells and various plant species, by generating reactive oxygen species (ROS). In response, plants positively or negatively regulate the expression of various families of genes and enzymes involved in physiological and metabolomic pathways of plants, such as carbon and nitrogen metabolism, which are directly involved in plant development and growth. Likewise, ROS can modulate the expression of enzymes and genes related to the adaptation of plants to stress, such as the glutathione ascorbate cycle, the shikimic acid, and phenylpropanoid pathways, from which the largest amount of biocompounds in plants are derived. This document exposes the ability of three CNMs (fullerene, graphene, and carbon nanotubes) to positively or negatively regulate the activity of enzymes and genes involved in various plant species' primary and secondary metabolism. The mechanism of action of CNMs on the production of biocompounds and the effect of the translocation of CNMs on the growth and content of primary metabolites in plants are described. Adverse effects of CNMs on plants, prospects, and possible risks involved are also discussed. The use of CNMs as inducers of biocompounds in plants could have implications and relevance for human health, crop quality, and plant adaptation and resistance to biotic and abiotic stress.

Unveiling key mechanisms: Transcriptomic meta-analysis of diverse nanomaterial applications addressing biotic and abiotic stresses in Arabidopsis Thaliana

The potential applications of nanomaterials in agriculture for alleviating diverse biotic and abiotic stresses have garnered significant attention. The reported mechanisms encompass promoting plant growth and development, alleviating oxidative stress, inducing defense responses, modulating plant-microbe interactions, and more. However, individual studies may not fully uncover the common pathways or distinguish the effects of different nanostructures. We examined Arabidopsis thaliana transcriptomes exposed to biotic, abiotic, and metal or carbon-based nanomaterials, utilizing 24 microarray chipsets and 17 RNA-seq sets. The results showed that: 1) from the perspective of different nanostructures, all metal nanomaterials relieved biotic/abiotic stresses via boosting metal homeostasis, particularly zinc and iron. Carbon nanomaterials induce hormone-related immune responses in the presence of both biotic and abiotic stressors. 2) Considering the distinct features of various nanostructures, metal nanomaterials displayed unique characteristics in seed priming for combating abiotic stresses. In contrast, carbon nanomaterials exhibited attractive features in alleviating water deprivation and acting as signaling amplifiers during biotic stress. 3) For shared pathway analysis, response to hypoxia emerges as the predominant and widely shared regulatory mechanism governing diverse stress responses, including those induced by nanomaterials. By deciphering shared and specific pathways and responses, this research opens new avenues for precision nano-agriculture, offering innovative strategies to optimize plant resilience, improve stress management, and advance sustainable crop production practices.

Azospirillum brasilense activates peroxidase-mediated cell wall modification to inhibit root cell elongation

The molecular mechanism of beneficial bacterium Azospirillum brasilense-mediated root developmental remain elusive. A. brasilense elicited extensively transcriptional changes but inhibited primary root elongation in Arabidopsis. By analyzing root cell type-specific developmental markers, we demonstrated that A. brasilense affected neither overall organization nor cell division of primary root meristem. The cessation of primary root resulted from reduction of cell elongation, which is probably because of bacterially activated peroxidase that will lead to cell wall cross-linking at consuming of H2O2. The activated peroxidase combined with downregulated cell wall loosening enzymes consequently led to cell wall thickness, whereas inhibiting peroxidase restored root growth under A. brasilense inoculation. We further showed that peroxidase activity was probably promoted by cadaverine secreted by A. brasilense. These results suggest that A. brasilense inhibits root elongation by activating peroxidase and inducing cell wall modification in Arabidopsis, in which cadaverine released by A. brasilense is a potential signal compound.

Rapid quantitative detection of luteolin using an electrochemical sensor based on electrospinning of carbon nanofibers doped with single-walled carbon nanoangles

In this study, single-walled carbon nanoangles/carbon nanofibers (SWCNHs/CNFs) were synthesized by electrospinning, followed by annealing in a N₂ atmosphere. The synthesized composite was structurally characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical sensor was fabricated by modifying a glassy carbon electrode (GCE) for luteolin detection, and its electrochemical characteristics were investigated using differential pulse voltammetry, cyclic voltammetry, and chronocoulometry. Under optimized conditions, the response range of the electrochemical sensor to luteolin was 0.01-50 μM, and the detection limit was 3.714 nM (S/N = 3). The SWCNHs/CNFs/GCE sensor showed excellent selectivity, repeatability, and reproducibility, thus enabling the development of an economical and practical electrochemical method for the detection of luteolin.

Effects of foliar application of single-walled carbon nanotubes on carbohydrate metabolism in crabapple plants

Carbon nanotubes (CNTs) regulate growth in many plants. Carbohydrates provide energy and carbon skeleton for cell growth. However, how CNTs influence plant carbohydrate metabolism remains largely unknown. For a comprehensive understanding the response of carbohydrate metabolism and accumulation in leaves of crabapple (Malus hupehensis Rehd) to single-walled carbon nanotubes (SWCNTs), the expression of key enzymes and genes involved in apple sugar metabolism was investigated. In this report, TEM showed that SWCNTs particles were absorbed in apple leaf. Foliar application of 10 and 20 mg/L SWCNTs promoted chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate. SWCNTs up-regulate the activity of aldose-6-phosphate reductase (A6PR), accompanied by increased concentration of photosynthetic assimilate‒sorbitol. However, the activities of sucrose phosphate synthase (SPS) and the accumulation of sucrose did not change significantly in SWCNTs-sprayed apple leaves compared with the control. In addition, the activities of photoassimilate degradation enzyme (sorbitol dehydrogenase, SDH; sucrose synthase, SUSY; neutral invertase, NINV) and hexose degradation enzyme (fructokinase, FRK; hexokinase, HK) were higher in SWCNTs-treated apple leaves than that in the control leaves. Quantitative real-time polymerase chain reaction (qRT‒PCR) results indicated that the expression of genes associated with sugar metabolism changed significantly after SWCNTs application. Taken together, we propose that spraying apple leaves with 10 and 20 mg/L SWCNTs can improve photosynthetic activity and accelerate carbohydrate metabolism in apple leaves. Our results provide insight into understanding the biological effects of CNTs in plants and are valuable for continued use of SWCNTs in agri-nanotechnology.

The behavior, transport, and positive regulation mechanism of ZnO nanoparticles in a plant-soil-microbe environment

ZnO nanoparticles (ZnO NPs) have been widely used in several fields, and they have the potential to be a novel fertilizer to promote plant growth. For the effective use of ZnO NPs, it is necessary to understand their influence mechanisms and key interactions with the soil physical and biological environment. In this review, we summarize the fate and transport of ZnO NPs applied via soil treatment or foliar spray in plant-soil systems and discuss their positive regulation mechanisms in plants and microbes. The latest research shows that the formation, bioavailability, and location of ZnO NPs experience complicated changes during the transport in soil-plant systems and that this depends on many factors. ZnO NPs can improve plant photosynthesis, nutrient element uptake, enzyme activity, and the related gene expression as well as modulate carbon/nitrogen metabolism, secondary metabolites, and the antioxidant systems in plants. Several microbial groups related to plant growth, disease biocontrol, and nutrient cycling in soil can be altered with ZnO NP treatment. In this work, we present a systematic comparison between ZnO NP fertilizer and conventional zinc salt fertilizer. We also fill several knowledge gaps in current studies with the hope of providing guidance for future research.

Molecular and genetic analyses revealed the phytotoxicity of perfluorobutane sulfonate

Perfluorobutane sulfonate (PFBS) has oily and hydrophobic characteristics similar to those of perfluorooctane sulfonic acid (PFOS), which is an environmental organic pollutant and has gradually become the main substitute for PFOS in industry. Several studies have revealed the potential toxicity of PFBS in animals. PFBS can be taken up and accumulate in plants; however, whether and how PFBS affects plant growth remain largely unclear. A low concentration of PFBS did not affect plant growth, indicating that it had higher environmental safety than other perfluorinated compounds; however, a high concentration of PFBS (>1 mM) markedly inhibited primary root growth in Arabidopsis thaliana. Subsequently, we investigated the molecular mechanisms underlying plant growth mediated by high concentrations of PFBS. First, a genome-wide transcriptomic analysis revealed that PFBS altered the expression of genes associated with phytohormone signaling pathways. Combining physio-biochemical and genetic analyses, we next demonstrated that PFBS reduced the contents of indole-3-acetic acid (IAA) and abscisic acid (ABA), and disrupted the two signaling pathways in plants, finally inhibiting root growth. Moreover, a high concentration of PFBS also inhibited photosynthesis by comprehensively repressing the expression of genes related to the Calvin cycle and the photosynthetic apparatus. Such an understanding is helpful for elucidating the phytotoxicity of PFBS and provides a new strategy for toxicology research on organic pollutants in plants.

Insights into growth-promoting effect of nanomaterials: Using transcriptomics and metabolomics to reveal the molecular mechanisms of MWCNTs in enhancing hyperaccumulator under heavy metal(loid)s stress

Carbon nanotubes present potential applications in soil remediation, particularly in phytoremediation. Yet, how multi-walled carbon nanotubes (MWCNTs) induced hyperaccumulator growth at molecular level remains unclear. Here, physio-biochemical, transcriptomic, and metabolomic analyses were performed to determine the effect of MWCNTs on Solanum nigrum L. (S. nigrum) growth under cadmium and arsenic stresses. 500 mg/kg MWCNTs application significantly promoted S. nigrum growth, especially for root tissues. Specially, MWCNTs application yields 1.38-fold, 1.56-fold, and 1.37-fold enhancement in the shoot length, root length, and fresh biomass, respectively. Furthermore, MWCNTs significantly strengthened P and Fe absorption in roots, as well as the activities of antioxidative enzymes. Importantly, the transcriptomic analysis indicated that S. nigrum gene expression was sensitive to MWCNTs, and MWCNTs upregulated advantageous biological processes under heavy metal(loid)s stress. Besides, MWCNTs reprogramed metabolism that related to defense system, leading to accumulation of 4-hydroxyphenylpyruvic acid (amino acid), 4-hydroxycinnamic acid (xenobiotic), and (S)-abscisic acid (lipid). In addition, key common pathways of differentially expressed metabolites and genes, including "tyrosine metabolism" and "isoquinoline alkaloid biosynthesis" were selected via integrating transcriptome and metabolome analyses. Combined omics technologies, our findings provide molecular mechanisms of MWCNTs in promoting S. nigrum growth, and highlight potential application of MWCNTs in soil remediation.

Advances in Plant Metabolomics and Its Applications in Stress and Single-Cell Biology

In the past two decades, the post-genomic era envisaged high-throughput technologies, resulting in more species with available genome sequences. In-depth multi-omics approaches have evolved to integrate cellular processes at various levels into a systems biology knowledge base. Metabolomics plays a crucial role in molecular networking to bridge the gaps between genotypes and phenotypes. However, the greater complexity of metabolites with diverse chemical and physical properties has limited the advances in plant metabolomics. For several years, applications of liquid/gas chromatography (LC/GC)-mass spectrometry (MS) and nuclear magnetic resonance (NMR) have been constantly developed. Recently, ion mobility spectrometry (IMS)-MS has shown utility in resolving isomeric and isobaric metabolites. Both MS and NMR combined metabolomics significantly increased the identification and quantification of metabolites in an untargeted and targeted manner. Thus, hyphenated metabolomics tools will narrow the gap between the number of metabolite features and the identified metabolites. Metabolites change in response to environmental conditions, including biotic and abiotic stress factors. The spatial distribution of metabolites across different organs, tissues, cells and cellular compartments is a trending research area in metabolomics. Herein, we review recent technological advancements in metabolomics and their applications in understanding plant stress biology and different levels of spatial organization. In addition, we discuss the opportunities and challenges in multiple stress interactions, multi-omics, and single-cell metabolomics.

Comparative cytology combined with transcriptomic and metabolomic analyses of Solanum nigrum L. in response to Cd toxicity

Cadmium (Cd) triggers molecular alterations in plants, perturbs metabolites and damages plant growth. Therefore, understanding the molecular mechanism underlying the Cd tolerance in plants is necessary for assessing the persistent environmental impact of Cd. In this study, Solanum nigrum was selected as the test plant to investigate changes in biomass, Cd translocation, cell ultrastructure, metabolites and genes under hydroponic conditions. The results showed that the plant biomass was significantly decreased under Cd stress, and the plant has a stronger Cd transport capability. Transmission electron microscopy revealed that increased Cd concentration gradually damaged the plant organs (roots, stems and leaves) cell ultrastructure, as evidenced by swollen chloroplasts and deformed cell walls. Additionally, metabolomics analyses revealed that Cd stress mainly affected seven metabolism pathways, including 19 differentially expressed metabolites (DEMs). Moreover, 3908 common differentially expressed genes (DEGs, 1049 upregulated and 2859 downregulated) were identified via RNA-seq among five Cd treatments. Meanwhile, conjoint analysis found several DEGs and DEMs, including laccase, peroxidase, D-fructose, and cellobiose etc., are associated with cell wall biosynthesis, implying the cell wall biosynthesis pathway plays a critical role in Cd detoxification. Our comprehensive investigation using multiple approaches provides a molecular-scale perspective on plant response to Cd stress.

Self-enhanced photoelectrochemical sensor based on a Schottky heterostructure organic electron donor matrix

A self-enhanced photoelectrochemical copper ions sensor was constructed using an organic electron donor matrix with a Schottky heterostructure prepared from dopamine and single walled carbon nanohorns. The determination of Cu²⁺ with no additional electron donor solution, with high sensitivity and low background, provides new inspiration for the development of photoelectric sensing.

Nanotechnology advances for sustainable agriculture: current knowledge and prospects in plant growth modulation and nutrition

Advances in nanotechnology make it an important tool for improving agricultural production. Strong evidence supports the role of nanomaterials as nutrients or nanocarriers for the controlled release of fertilizers to improve plant growth. Scientific research shows that nanotechnology applied in plant sciences is smart technology. Excessive application of mineral fertilizers has produced a harmful impact on the ecosystem. Furthermore, the projected increase in the human population by 2050 has led to the search for alternatives to ensure food security. Nanotechnology is a promising strategy to enhance crop productivity while minimizing fertilizer inputs. Nanofertilizers can contribute to the slow and sustainable release of nutrients to improve the efficiency of nutrient use in plants. Nanomaterial properties (i.e., size, morphology and charge) and plant physiology are crucial factors that influence the impact on plant growth. An important body of scientific research highlights the role of carbon nanomaterials, metal nanoparticles and metal oxide nanoparticles to improve plant development through the modulation of physiological and metabolic processes. Modulating nutrient concentrations, photosynthesis processes and antioxidant enzyme activities have led to increases in shoot length, root development, photosynthetic pigments and fruit yield. In parallel, nanocarriers (nanoclays, nanoparticles of hydroxyapatite, mesoporous silica and chitosan) have been shown to be an important tool for the controlled and sustainable release of conventional fertilizers to improve plant nutrition; however, the technical advances in nanofertilizers need to be accompanied by modernization of the regulations and legal frameworks to allow wider commercialization of these elements. Nanofertilizers are a promising strategy to improve plant development and nutrition, but their application in sustainable agriculture remains a great challenge. The present review summarizes the current advance of research into nanofertilizers, and their future prospects.

Molecular mechanisms of zooplanktonic toxicity in the okadaic acid-producing dinoflagellate Prorocentrum lima

Prorocentrum lima is a dinoflagellate that forms hazardous blooms and produces okadaic acid (OA), leading to adverse environmental consequences associated with the declines of zooplankton populations. However, little is known about the toxic effects and molecular mechanisms of P. lima or OA on zooplankton. Here, their toxic effects were investigated using the brine shrimp Artemia salina. Acute exposure of A. salina to P. lima resulted in lethality at concentrations 100-fold lower than densities observed during blooms. The first comprehensive results from global transcriptomic and metabolomic analyses in A. salina showed up-regulated mRNA expression of antioxidant enzymes and reduced non-enzyme antioxidants, indicating general detoxification responses to oxidative stress after exposure to P. lima. The significantly up-regulated mRNA expression of proteasome, spliceosome, and ribosome, as well as the increased fatty acid oxidation and oxidative phosphorylation suggested the proteolysis of damaged proteins and induction of energy expenditure. Exposure to OA increased catabolism of chitin, which may further disrupt the molting and reproduction activities of A. salina. Our data shed new insights on the molecular responses and toxicity mechanisms of A. salina to P. lima or OA. The simple zooplankton model integrated with omic methods provides a sensitive assessment approach for studying hazardous algae.

Physiological and molecular responses in halotolerant Dunaliella salina exposed to molybdenum disulfide nanoparticles

Molybdenum disulfide nanoparticles (MoS₂ NPs) has emerged as the promising nanomaterial with a wide array of applications in the biomedical, industrial and environmental field. However, the potential effect of MoS₂ NPs on marine organisms has yet to be reported. In this study, the effect of MoS₂ NPs on the physiological index, subcellular morphology, transcriptomic profiles of the marine microalgae Dunaliella salina was investigated for the first time. exhibited "doping-like" effects on marine microalgae; Growth stimulation was 193.55%, and chlorophyll content increased 1.61-fold upon the addition of 50 μg/L MoS₂ NPs. Additionally, exposure to MoS₂ NPs significantly increased the protein and carbohydrate content by 2.03- and 1.56-fold, respectively. The antioxidant system was activated as well to eliminate the adverse influence of reactive oxygen species (ROS). Transcriptomic analysis revealed that genes involved in porphyrin synthesis, glycolysis/gluconeogenesis, tricarboxylic acid cycle and DNA replication were upregulated upon MoS₂ NPs exposure, which supports the mechanistic role of MoS₂ NPs in improving cellular growth and photosynthesis. The "doping-like" effects on marine algae suggest that the low concentration of MoS₂ NPs might change the rudimentary ecological composition in the ocean.

Dual Effect of Nanomaterials on Germination and Seedling Growth: Stimulation vs. Phytotoxicity

Due to recent active research, a large amount of data has been accumulated regarding the effects of different nanomaterials (mainly metal oxide nanoparticles, carbon nanotubes, chitosan nanoparticles) on different plant species. Most studies have focused on seed germination and early seedling development, presumably due to the simplicity of these experimental systems. Depending mostly on size and concentration, nanomaterials can exert both positive and negative effects on germination and seedling development during normal and stress conditions, thus some research has evaluated the phytotoxic effects of nanomaterials and the physiological and molecular processes behind them, while other works have highlighted the favorable seed priming effects. This review aims to systematize and discuss research data regarding the effect of nanomaterials on germination and seedling growth in order to provide state-of-the-art knowledge about this fast developing research area.

Nanoparticles in Agroindustry: Applications, Toxicity, Challenges, and Trends

Nanotechnology is a tool that in the last decade has demonstrated multiple applications in several sectors, including agroindustry. There has been an advance in the development of nanoparticulated systems to be used as fertilizers, pesticides, herbicides, sensors, and quality stimulants, among other applications. The nanoencapsulation process not only protects the active ingredient but also can affect the diffusion, interaction, and activity. It is important to evaluate the negative aspects of the use of nanoparticles (NPs) in agriculture. Given the high impact of the nanoparticulated systems in the agro-industrial field, this review aims to address the effects of various nanomaterials on the morphology, metabolomics, and genetic modification of several crops.