Quaternary ammonium iminofullerenes improve root growth of oxidative-stress maize through ASA-GSH cycle modulating redox homeostasis of roots and ROS-mediated root-hair elongation

Carbohydrate-Derived Superhydrophilic Carbon Aerogels and Their Effects on Seedling Growth of Triticum aestivum

Synthesis methods of carbon nanomaterials have been developed vigorously in recent years, among which a simple, green, and mature approach is of more research significance. Carbon nanomaterials have depicted an impact on the growth and development of plants. In this study, a new type of carbon nanomaterial, superhydrophilic carbon aerogel (CA), was synthesized via a hydrothermal process using carbohydrates and water-soluble polymers as raw materials. Characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, and N2 adsorption analysis, the exemplified CA presented to have porous three-dimensional network structure composed of individual particles with diameters of 25 nm, with reactive surface, single composition, high specific surface area (89.94 m2·g-1), and wide range of density variation. The 9 mg·mL-1 CA suspension had a significant positive effect on the root growth of wheat seedlings, with promoted root elongation (about 67.17% longer) and root diameter (about 28.95% thicker) compared with those of the control group. The cytological results suggested that CA treatment triggered the propagation of meristematic cells, and the increased number of meristematic cells (65.79% more than the control group) led to enhanced root growth by upregulated expression of related phytohormone genes in wheat seedlings.

Calcium Hexacyanoferrate Nanozyme Enhances Plant Stress Resistance by Oxidative Stress Alleviation and Heavy Metal Removal

Oxidative damage, exacerbated by the excessive accumulation of reactive oxygen species (ROS), profoundly inhibits both crop growth and yield. Herein, a biocompatible nanozyme, calcium hexacyanoferrate nanoparticles (CaHCF NPs), targeting ROS is developed, to mitigate oxidative damage and sequestrate heavy metal ions during plant growth. Uniquely, CaHCF NPs feature multifaced enzyme-like activities, involving superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase, thiol peroxidase, and ascorbate peroxidase, which enable them to neutralize excessive ROS. Furthermore, CaHCF NPs promote calcium-cadmium exchange process, diminishing the uptake of heavy metals. Importantly, 120 µg mL-1 of CaHCF NPs alleviate the inhibitory effects of hydrogen peroxide and cadmium chloride on Arabidopsis and tomato. The activities of SOD, POD, and CAT increase by 46.2%, 74.4%, and 48.3%, respectively, meanwhile the glutathione level rises by 72.4% in Arabidopsis under cadmium stress. Moreover, CaHCF NPs boost the expression of genes associated with antioxidation, heavy metal detoxification, nutrient transport, and stress resistance. These findings unveil the significant potential of nanoplatforms equipped with nanozymes in alleviating oxidative stress in plants, which not only regulate crop growth but also substantially ameliorate yield and quality, heralding a new era in agricultural nanotechnology.

Cu-II-directed self-assembly of fullerenols to ameliorate copper stress in maize seedlings

Widespread use of copper-based agrochemical may cause copper excessive accumulation in agricultural soil to seriously threaten crop production. Recently, fullerenols are playing important roles in helping crops build resistance to abiotic stresses by giving ingenious and successful resolutions. However, there is a lack of knowledge on their beneficial effects in crops under stresses induced by heavy metals. Herein, the visual observation of Cu2+-mediated assembly of fullerenols via electrostatic and coordination actions was carried out in vitro, showing that water-soluble nanocomplexes and water-insoluble cross-linking nanohybrids were selectively fabricated by precisely adjusting feeding ratios of fullerenols and CuSO4. Furthermore, maize simultaneous exposure of fullerenols and CuSO4 solutions was tested to investigate the comparative effects of seed germination and seedling growth relative to exposure of CuSO4 alone. Under moderate Cu2+ stresses (40 and 80 μM), fullerenols significantly mitigated the detrimental effects of seedlings, including phenotype, root and shoot elongation, biomass accumulation, antioxidant capacity, and Cu2+ uptake and copper transporter-related gene expressions in roots. Under 160 μM of Cu2+ as a stressor, fullerenols also accelerated germination of Cu2+-stressed seeds eventually up to the level of the control. Summarily, fullerenols can enhance tolerance of Cu2+-stressed maize mainly due to direct detoxification through fullerenol-Cu2+ interactions restraining the Cu2+ intake into roots and reducing free Cu2+ content in vivo, as well as fullerenol-maize interactions to enhance resistance by maintaining balance of reactive oxygen species and optimizing the excretion and transport of Cu2+. This will unveil valuable insights into the beneficial roles of fullerenols and its mechanism mode in alleviating heavy metal stress on crop plants.

Application of carbon nanostructures in biomedicine: realities, difficulties, prospects

The review systematizes data on the wide possibilities of practical application of carbon nanostructures. Much attention is paid to the use of carbon nanomaterials in medicine for the visualization of tumors during surgical interventions, in the creation of cosmetics, as well as in agriculture in the creation of fertilizers. Additionally, we demonstrate trends in research in the field of carbon nanomaterials with a view to elaborating targeted drug delivery systems. We also show the creation of nanosized medicinal substances and diagnostic systems, and the production of new biomaterials. A separate section is devoted to the difficulties in studying carbon nanomaterials. The review is intended for a wide range of readers, as well as for experts in the field of nanotechnology and nanomedicine.

Non-bone-derived exosomes: a new perspective on regulators of bone homeostasis

Accumulating evidence indicates that exosomes help to regulate bone homeostasis. The roles of bone-derived exosomes have been well-described; however, recent studies have shown that some non-bone-derived exosomes have better bone targeting ability than bone-derived exosomes and that their performance as a drug delivery vehicle for regulating bone homeostasis may be better than that of bone-derived exosomes, and the sources of non-bone-derived exosomes are more extensive and can thus be better for clinical needs. Here, we sort non-bone-derived exosomes and describe their composition and biogenesis. Their roles and specific mechanisms in bone homeostasis and bone-related diseases are also discussed. Furthermore, we reveal obstacles to current research and future challenges in the practical application of exosomes, and we provide potential strategies for more effective application of exosomes for the regulation of bone homeostasis and the treatment of bone-related diseases. Video Abstract.

Advances in the Involvement of Metals and Metalloids in Plant Defense Response to External Stress

Plants, as sessile organisms, uptake nutrients from the soil. Throughout their whole life cycle, they confront various external biotic and abiotic threats, encompassing harmful element toxicity, pathogen infection, and herbivore attack, posing risks to plant growth and production. Plants have evolved multifaceted mechanisms to cope with exogenous stress. The element defense hypothesis (EDH) theory elucidates that plants employ elements within their tissues to withstand various natural enemies. Notably, essential and non-essential trace metals and metalloids have been identified as active participants in plant defense mechanisms, especially in nanoparticle form. In this review, we compiled and synthetized recent advancements and robust evidence regarding the involvement of trace metals and metalloids in plant element defense against external stresses that include biotic stressors (such as drought, salinity, and heavy metal toxicity) and abiotic environmental stressors (such as pathogen invasion and herbivore attack). We discuss the mechanisms underlying the metals and metalloids involved in plant defense enhancement from physiological, biochemical, and molecular perspectives. By consolidating this information, this review enhances our understanding of how metals and metalloids contribute to plant element defense. Drawing on the current advances in plant elemental defense, we propose an application prospect of metals and metalloids in agricultural products to solve current issues, including soil pollution and production, for the sustainable development of agriculture. Although the studies focused on plant elemental defense have advanced, the precise mechanism under the plant defense response still needs further investigation.

Exploring the mechanism of exopolysaccharides in mitigating cadmium toxicity in rice through analyzing the changes of antioxidant system

Recently, exopolysaccharides (EPS) were found to alleviate cadmium (Cd) toxicity to crops by regulating the antioxidant system, but the mechanism remains unclear. Herein, by quantitative and transcriptomic approaches, a systematical map of the changes in the antioxidant system was drawn to dissected the underlying mechanism. The results demonstrated that the ascorbate-glutathione cycle (ASA-GSH cycle) is a major contributor. Specifically, compared to the control, the rice exposed to Cd exhibited a significant increase in the GSH pool (about 9-fold at 7 d), but a continuous decrease in the ASA pool (only 15.42% remained at 15 d) and an excessive accumulation of reactive oxygen species (ROS). Interestingly, with the addition of EPS, the increase of the GSH pool significantly slowed down (decreased by 180.18% at 7 d, compared to the Cd-stressed treatment), and the ASA pool remained high (consistently above 70.00% of the control group). ROS also maintained at a good level. Moreover, the activities of enzymatic antioxidants showed the similar trend. By RNA-Seq analysis, multiple genes enriched in ASA-GSH related pathway were screened (such as OsRBOHB, OsGST, OsPOD) for further study. This study provides a foundation for EPS application in agriculture, which also establishes a better way for analyzing antioxidant system.

Directed assembly of fullerenols via electrostatic and coordination interactions to fabricate diverse and water-soluble metal cation-fullerene nanocluster complexes

Metal ion-nanocluster coordination complexes can produce a variety of functional engineered nanomaterials with promising characteristics to enable widespread applications. Herein, the visualization observation of the interactions of metal ions and fullerene derivatives, particularly anionic fullerenols (Fol), were carried out in aqueous solutions. The alkali metal salts only resulted in salting out of Fol to gain re-soluble sediments, whereas multivalent metal cations (Mn+, n = 2, 3) modulated further assembly of Fol to produce insoluble hybrids. These provide crucial insights into the directed assembly of Fol that two major forces involved in actuation are electrostatic and coordination effects. Through the precise modulation of feed ratios of Fol to Mn+, a variety of water-soluble Mn+@Fol coordination complexes were facilely prepared and subsequently characterized by various measurements. Among them, X-ray photoelectron spectra validated the coordination effects through the metal cation and oxygen binding feature. Transmission electron microscopy delivered valuable information about diverse morphologies and locally-ordered microstructures at the nanoscale. This study opens a new opportunity for developing a preparation strategy to fabricate water-soluble metal cation-fullerenol coordination complexes with various merits for potential application in biomedical fields.

Potential roles of iron nanomaterials in enhancing growth and nitrogen fixation and modulating rhizomicrobiome in alfalfa (Medicago sativa L.)

Iron (Fe) is one of the essential nutrient elements for plant growth and development. However, the potential roles of iron nanomaterials in regulating growth and nitrogen fixation and modulating rhizomicrobiome in legume plants are poorly known. In this study, we reported that 10 mg L-1 is the optimal concentration for the application of iron nanoparticles (FeNPs) and seed soaking plus leaf spraying is the optimal application method of FeNPs in alfalfa (Medicago sativa L.); FeNPs had more positive effects on the growth and nitrogen fixation capability in alfalfa than FeCl2; FeNPs enhanced the intensity of corporations and competitions among rhizosphere fungal taxa of alfalfa. This work provides insights into the regulation mechanism of FeNPs on growth, nitrogen fixation, and the composition and function of rhizosphere microbial community in legume plants as well as the potential application value of FeNPs in agriculture system.

Foliar spraying of exogenous uniconazole (S3307) at the flowering stage as an effective method to resist low-temperature stress on mung bean [Vigna radiata (L.) Wilczek]

Low temperature is one of the major constraints on agricultural productivity worldwide and is likely to further increase. Several adaptations and mitigation strategies are required to cope with low-temperature stress. Uniconazole (S3307) could play a significant role in the alleviation of abiotic stress in plants. In this study, the effects of S3307 on the reactive oxygen species (ROS) and antioxidant metabolism were studied in the leaves of mung bean [Vigna radiata (L.) Wilczek]. The experimental results showed that the low-temperature induced accumulation of superoxide anion (O2-) production rate, and malonaldehyde (MDA) contents. Increased proline content and enzymatic antioxidants, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), were found to alleviate oxidative damage under low temperatures. While, S3307 could reduce O2- production rate and MDA contents and increase the activities of SOD, POD, and CAT, slowed the decrease in ascorbic acid (AsA), dehydroascorbic acid (DHA), glutathione (GSH), and oxidized glutathione (GSSG), and promoted increase in soluble sugars (SS), soluble proteins (SP), and proline (Pro) content under low-temperature. At the same time, low temperature leads to lower 100 grain weight and number of grains per plant, which eventually causes yield reduction decreased. Foliar spraying of S3307 could alleviate the yield loss caused by low temperature, and the increase of S3307 treatment was 5.1%-12.5% and 6.3%-32.9% for the two varieties, respectively, compared with CK. In summary, exogenous S3307 pretreatment enhances plant tolerance to low-temperature by improving the antioxidant enzyme activities, increased non-enzymatic antioxidants content, and decreased O2- production rate and MDA contents and inducing alterations in endogenous S3307, and reduce the decrease in mung bean yield.

Dimethyl Bisphenolate Ameliorates Carbon Tetrachloride-Induced Liver Injury by Regulating Oxidative Stress-Related Genes

Liver disease accounts for millions of deaths per year all over the world due to complications from cirrhosis and liver injury. In this study, a novel compound, dimethyl bisphenolate (DMB), was synthesized to investigate its role in ameliorating carbon tetrachloride (CCl4)-induced liver injury through the regulation of oxidative stress-related genes. The structure of DMB was confirmed based on its hydrogen spectrum and mass spectrometry. DMB significantly reduced the high levels of ALT, AST, DBIL, TBIL, ALP, and LDH in a dose-dependent manner in the sera of CCl4-treated rats. The protective effects of DMB on biochemical indicators were similar to those of silymarin. The ROS fluorescence intensity increased in CCl4-treated cells but significantly weakened in DMB-treated cells compared with the controls. DMB significantly increased the content of oxidative stress-related GSH, Nrf2, and GCLC dose-dependently but reduced MDA levels in CCl4-treated cells or the liver tissues of CCl4-treated rats. Moreover, DMB treatment decreased the expression levels of P53 and Bax but increased those of Bcl2. In summary, DMB demonstrated protective effects on CCl4-induced liver injury by regulating oxidative stress-related genes.

Physiological, biochemical, and metabolic changes in diploid and triploid watermelon leaves during flooding

Background

Flooding is a major stress factor impacting watermelon growth and production globally. Metabolites play a crucial role in coping with both biotic and abiotic stresses.

Methods

In this study, diploid (2X) and triploid (3X) watermelons were investigated to determine their flooding tolerance mechanisms by examining physiological, biochemical, and metabolic changes at different stages. Metabolite quantification was done using UPLC-ESI-MS/MS and a total of 682 metabolites were detected.

Results

The results showed that 2X watermelon leaves had lower chlorophyll content and fresh weights compared to 3X. The activities of antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were higher in 3X than in 2X. 3X watermelon leaves showed lower O2 production rates, MDA, and hydrogen peroxide (H2O2) levels in response to flooding, while higher ethylene production was observed. 3X had higher levels of dehydrogenase activity (DHA) and ascorbic acid + dehydrogenase (AsA + DHA), but both 2X and 3X showed a significant decline in the AsA/DHA ratio at later stages of flooding. Among them, 4-guanidinobutyric acid (mws0567), an organic acid, may be a candidate metabolite responsible for flooding tolerance in watermelon and had higher expression levels in 3X watermelon, suggesting that triploid watermelon is more tolerant to flooding.

Conclusion

This study provides insights into the response of 2X and 3X watermelon to flooding and the physiological, biochemical, and metabolic changes involved. It will serve as a foundation for future in-depth molecular and genetic studies on flooding response in watermelon.