Mesoporous Silica Nanoparticles Induce Intracellular Peroxidation Damage of Phytophthora infestans: A New Type of Green Fungicide for Late Blight Control

ZnO quantum dots reduce acquisition of huanglongbing pathogen by Diaphorina citri

BACKGROUND

Diaphorina citri Kuwayama is the main vector of the Huanglongbing (HLB) pathogen Candidatus Liberibacter asiaticus (CLas). Therefore, reducing CLas acquisition by D. citri is crucial for controlling the spread of HLB.

RESULTS

This study aimed to investigate the effect of ZnO quantum dots (ZnO QDs) on CLas acquisition by D. citri. The results showed that ZnO QDs were absorbed by citrus plants and D. citri, inducing reactive oxygen species generation in the intestine and causing intestinal cell apoptosis. The uptake rate of CLas was reduced to 75% and 22.3% after treatment with 2 and 5 mg ∙ mL-1 ZnO QDs, respectively, compared with 100% in the control group. Transcription analysis showed significant changes in the expression of D. citri genes related to apoptosis, oxidative stress, and DNA replication and repair.

CONCLUSION

The results suggested that ZnO QDs could efficiently reduce CLas acquisition by D. citri, providing a safe and reliable tool for HLB prevention and control. © 2024 Society of Chemical Industry.

Zein and resveratrol Schiff base nanocomplexes: An efficient delivery system to enhance the antibacterial efficacy of berberine

Plant-derived bactericides with limited drug resistance and environmental friendliness are promising alternatives to traditional chemical bactericides. Berberine (BBR) is a natural product with excellent biological activity against bacteria. Novel pesticide delivery systems were designed and constructed based on the plant-derived zein resveratrol (RSV) and its derivative 4-((E)-((2-hydroxyphenyl)imino)methyl)-5-((E)-4-hydroxystyryl)benzene-1,3-diol (XF) to improve the efficacy of BBR. BBR@Zein-RSV and BBR@Zein-XF nanoparticles (NPs) had uniform dispersion and were approximately 119.19 and 86.82 nm, with encapsulation rates of 55.71 % and 83.34 %, respectively. BBR@Zein-RSV and BBR@Zein-XF NPs used dual pH and redox reaction mechanisms to achieve a controlled release into the environment. Especially, BBR@Zein-XF NPs exhibited antibacterial activity against Xanthomonas oryzae pv. oryzicola with an EC50 value of 0.98 mg/L. Additionally, it showed excellent protective (51.52 %) and curative (48.17 %) effects against rice bacterial leaf streaks. NPs could inhibit biofilm formation and extracellular polysaccharide production but promote reactive oxygen species levels, thereby destroying the integrity of bacteria and eventually leading to cell death. Proteomic analysis revealed that BBR@Zein-XF NPs regulated the expression of phosphoenolpyruvate carboxykinase and lactoylglutathione lyase, thereby influencing plant growth, energy metabolism, and maintaining a normal redox state. This study provides new ideas for extensively utilizing plant-derived antibacterial agents by developing innovative and eco-friendly nano-pesticides.

Lignin-enabled silica hybrid nanoparticles from rice husk for improved biopesticide delivery and cotton bollworm control

This study investigates the production of lignin/silica hybrid nanoparticles (LSNPs) from rice husk, an abundant agricultural byproduct, for the delivery of soybean trypsin inhibitor (STI), a bioinsecticide. Lignin was extracted from rice husk under alkaline conditions and co-precipitated with silica to form LSNPs. Characterization revealed that lignin imparted hydrophobicity to the nanoparticles and increased their surface area, enhancing their potential for pesticide delivery. The hybrid nanoparticles were evaluated for their ability to resist washout, control STI release, and provide effective biocontrol against cotton bollworm larvae - one of the most damaging pests in cotton crops. The results indicates that lignin played a critical role in imparting hydrophobicity to the nanoparticles, significantly enhancing their adhesion to hydrophobic plants such as cotton. The hybrid nano-formulations exhibited superior foliar adherence, washout resistance, and pH-responsive release (28.1 % at pH 9). STI delivered with LSNP achieved 99.1 % insect weight reduction, and complete (100 %) mortality rate compared to 75.8 % weight reduction and 66.7 % mortality rate when delivered by pure silica. This work highlights the synergistic potential of combining lignin and silica from the same bio-based source in enhancing both foliar adhesion and bioactivity of biopesticides, offering a promising alternative for sustainable pest management in agriculture.

The Potato StNAC2-StSABP2 Module Enhanced Resistance to Phytophthora infestans Through Activating the Salicylic Acid Pathway

Potato late blight is an important disease in potato production, which causes serious damage. Salicylic acid (SA) is a plant hormone involved in the regulation of potato (Solanum tuberosum) resistance to Phytophthora infestans. In this study, it was found that exogenous methyl salicylate (MeSA) treatment could significantly enhance the resistance of potato to P. infestans. RNA-seq results confirmed that SA was important for potato resistance to P. infestans. Salicylic acid binding protein 2 (SABP2) is a member of α/β hydrolase family, which can convert MeSA into SA to regulate the steady state of SA in plants. StSABP2 protein was obtained through prokaryotic expression, and enzymatic analysis in vitro confirmed that StSABP2 could transform MeSA into SA. In order to explore the function of StSABP2 in the process of plant resistance to P. infestans, we carried out virus-mediated gene silencing of StSABP2 in potato and transiently expressed StSABP2 in tobacco. The results showed that StSABP2 positively regulated plant resistance to P. infestans, and this process was achieved by mediating the transcription of SA signal and defence-related genes. Then we screened for the upstream regulator of StSABP2. The results of double luciferase and yeast one-hybrid analysis showed that StNAC2 could activate the transcription of StSABP2. The StNAC2-StSABP2 module regulated potato resistance to P. infestans by positively mediating the SA pathway. This study provides a new idea for improving host resistance to potato late blight by regulating the SA signal in potato and provides germplasm resources for potato resistance breeding.

From Spear to Shield: A Novel Antifungal Drug that Safely Enhances Rice Immune Defenses

The infection and resistance of pathogenic fungi pose a significant threat to food crop safety, highlighting the urgent need for new green antifungal agents. Fusarium acid (FA) with its simple and novel structure correlates with the principles of green pesticides and has demonstrated substantial broad-spectrum antifungal activity. In a previous study, several promising lead compounds were identified. This study focused on further optimizing lead compound A1. Its inhibitory effect was evaluated against six different pathogenic fungi and several new promising compounds were identified. Notably, the anti-Magnaporthe oryzae (M. oryzae) activity of compound B4 was significantly enhanced with an EC50 value of 910 ng/mL. Rice safety tests indicated that B4 not only exhibited no adverse effect on rice growth and chlorophyll synthesis but also induced plant immunity by increasing the levels of polyphenol oxidase (PPO), peroxidase (POD), and superoxide dismutase (SOD), and soluble sugars. Further investigations into the antifungal mechanism of B4 indicated that it enhanced the permeability and damage of the mycelial membrane, thereby leading to electrolyte leakage and the loss of essential cellular substances. Subsequently, B4 induced the production of reactive oxygen species (ROS) in M. oryzae cell, including •OH, •O2-, and 1O2, while promoting increased levels of malondialdehyde (MDA) and SOD enzyme activity. Rice infection tests indicated that B4 effectively inhibited M. oryzae conidia activity and inhibited melanin production. These findings indicated that FA derivatives hold significant potential as a new strategy for M. oryzae disease management and offer valuable insights for the control of plant fungal diseases.

Multi-stimuli-responsive pectin-coated dendritic mesoporous silica nanoparticles with Eugenol as a sustained release nanocarrier for the control of tomato bacterial wilt

BACKGROUND

Environmentally responsive nanoscale biocide delivery system enhances smart, regulated, and synergistic biocide application with precise biocide release. In this study, pectin-modified dendritic mesoporous silica nanoparticles (DMSNs) was used as a carrier to successfully construct a microenvironment-responsive (pH, temperature and enzyme) eugenol nano-biocide delivery system for the control of Ralstonia solanacearum infection.

RESULTS

The results showed that the specific surface area, pore size and surface activity of DMSNs significantly influence the biocide loading of eugenol, and the biocide loading capability was up to 72.50%. Eu@DMSNs/Pec had significant pH and pectinase stimulating effects, with varying release amounts under different temperature conditions. Compared with eugenol alone, Eu@DMSNs/Pec significantly enhanced the efficacy of eugenol. DMSNs assisted eugenol to induce peroxidation damage, produce ROS (•O2-, •OH and 1O2), achieve synergistic antibacterial effects, and had better rain erosion resistance and foliar retention rate based on pectin wettability and adhesion. Eu@DMSNs/Pec-FITC showed demonstrated efficient transport characteristics in tomato roots, stems and leaves, which enhanced the control effect on tomato bacterial wilt. In addition, Eu@DMSNs/Pec exert minimal influence on tomato seed germination and root growth, and have low toxicity to non-target organisms such as earthworms. Therefore, Eu@DMSNs/Pec environment-responsive nano-controlled release nanocarrier can effectively achieve accurate biocide release and reduce biocide dosage.

CONCLUSION

This work not only provides a pectin-modified DMSNs-based eugenol nanoscale biocide delivery system in response to specific environmental conditions of R. solanacearum infection but also elucidates the eugenol biocide loading, selective release ability and antibacterial mechanism of the system.

Development of morphology-dependent nanoselenium carriers for enhancing biological activity and reducing plant stress

Owing to their small size, morphology and release modification properties, nanopesticides are considered promising alternative strategies for enhancing biological activity and minimizing pesticide losses. In this study, we used a colloidal self-assembly method to develop a morphology-stable, regularly rod-shaped nanoselenium pesticide carrier (NSer), which was further modified with chitosan. After loading penthiopyrad (PEN), the biological activity of NSer@PEN and its impact on the physiological and biochemical processes of plants were further compared with those of spherical nanoselenium pesticides (NSes@PEN) and commercial materials (20 % PEN SC). The biological activities were quantified through the EC50 values, which revealed that NSer@PEN (0.71 mg/L) and NSes@PEN (1.09 mg/L) exhibited significantly greater activity against Colletotrichum orbiculare Arx compared to 20 % PEN SC (2.70 mg/L). Moreover, through further investigation into the impact of nanopesticides on plant root exudates, Fourier transform infrared spectroscopy (FTIR) and two-dimensional correlation spectroscopy (2D-COS) analysis revealed that the ketone CO bond exhibited the strongest binding affinity, and the CO bond of phenols contributed significantly to the binding of cucumber root exudates induced by NSer@PEN, resulting in a mild response of the plant. The morphology-dependent nanoselenium carriers developed in this work are expected to enhance biological activity and reduce plant stress caused by pesticides, tackling one of the application challenges of pesticides.

Boosting Rice Resilience: Role of Biogenic Nanosilica in Reducing Arsenic Toxicity and Defending against Herbivore

The use of nanoparticles is a promising ecofriendly strategy for mitigating both abiotic and biotic stresses. However, the physiological and defense response mechanisms of plants exposed to multiple stresses remain largely unexplored. Herein, we examined how foliar application of biogenic nanosilica (BNS) impacts rice plant growth, molecular defenses, and metabolic responses when subjected to arsenic (As) toxicity and infested by the insect Chilo suppressalis. We show that BNS significantly increased shoot and root silicon accumulation but reduced the shoot As content by 34.7% under herbivory. Additionally, BNS reduced C. suppressalis larval weight gain by 34.5 and 12.3% without and with As stress, respectively. Importantly, BNS enhanced antioxidant enzyme activity under As stress, herbivore attack, and combined pressures, surpassing the effects of traditional silicate fertilizers. BNS ultimately increased rice shoot biomass by 8.2-23.4% under the respective stress conditions compared to the control treatment. Moreover, while As stress alone diminished the plant's resistance to herbivores, BNS application countered this effect by increasing detoxifying compound (e.g., glutathione) production and antioxidant enzyme activity. This study highlights the impact of biotic and abiotic stress interactions on BNS-enhanced plant resilience mechanisms in rice plants, reallocating resources to counter heavy metal toxicity and herbivore damage in agroecosystems.

Efficient Control of Fusarium Head Blight and Reduction of Deoxynivalenol Accumulation by a Novel Nanopartner-Based Strategy

Chemical control of Fusarium head blight (FHB) in wheat plants is often challenged by the resistance outbreak and deoxynivalenol (DON) accumulation. Developing green partners for fungicides is crucial for reducing fungal growth, mycotoxin contamination, and agricultural fungicides input. Herein, we investigated the mechanism of MgO nanoparticles (NPs) in controlling FHB. The EC50 of MgO NPs on mycelial growth was 105.2 μg/mL. At this concentration, they inhibited the spore germination, DON production, and wheat colonization of Fusarium graminearum by 56.0%, 24.5%, and 43.8%, respectively, exhibiting superior performance compared to nine other bioactive NPs such as ZnO and TiO2. Importantly, MgO NPs showed an additive effect with carbendazim and azoxystrobin in inhibiting F. graminearum. The extracellular toxicity of MgO NPs against F. graminearum was mainly attributed to the inhibition of fungal growth and germination by oxidative damage, alkaline damage, and cell structure damage. Although MgO NPs could not be absorbed into mycelia, they (EC90) decreased the soluble protein content and DNA concentration of mycelia by 27.8% and 42.3%, respectively, and increased the pyruvate content by 67.4%, demonstrating that the intracellular toxicity was mainly based on their inhibition of protein and DNA production and promotion of carbohydrate degradation. With low risks to nontarget organisms, MgO NPs could be a promising nanopartner for fungicides to protect wheat from FHB and mitigate fungicide overuse.

Multifaceted impacts of nanoparticles on plant nutrient absorption and soil microbial communities

With the growth of the global population and the increasing scarcity of resources, the sustainability and efficiency improvement of agricultural production have become urgent needs. The rapid development of nanotechnology provides new solutions to this challenge, especially the application of nanoparticles in agriculture, which is gradually demonstrating its unique advantages and broad prospects. Nonetheless, various nanoparticles can influence plant growth in diverse manners, often through distinct mechanisms of action. Beyond their direct effects on the plant itself, they frequently alter the physicochemical properties of the soil and modulate the structure of microbial communities in the rhizosphere. This review focuses intently on the diverse methods through which nanoparticles can modulate plant growth, delving deeply into the interactions between nanoparticles and plants, as well as nanoparticles with soil and microbial communities. The aim is to offer a comprehensive reference for the utilization of functionalized nanoparticles in the agricultural sector.

Sustainable and Biosafe Approach to Control Potato Late Blight Using Mesoporous Silica Nanoparticles

Phytophthora infestans-induced potato late blight is considered the "cancer of the potato crop." In this work, mesoporous silica nanoparticles (MSNs) with ultrahigh specific surface area (786.28 m2/g) were synthesized, which significantly inhibited P. infestans compared with some commercial fungicides. Moreover, MSNs inhibited the growth and reproductive of P. infestans processes, including germination, sporangia infection, and zoospore release. MSNs targeted key biological pathways and induced a stress response in the P. infestans, leading to reactive oxygen species (•O2-, •OH, and 1O2) production and structural damage of sporangia. Pot experiments showed that MSNs are translocated from leaves to roots of potato plants, enhancing physiological and biochemical processes, alleviating drought stress, improving resistance to pathogens, and exhibiting soil microbe-friendly. This study systematically reveals the mechanism of MSNs to weaken the reproduction process of P. infestans and confirm the safety and feasibility of MSNs as a green and sustainable fungicide.

Cestrum tomentosum L.f. Extracts against Colletotrichum scovillei by Altering Cell Membrane Permeability and Inducing ROS Accumulation

Chili pepper anthracnose, caused by Colletotrichum spp., is a significant biotic stress affecting chili fruits globally. While fungicide application is commonly used for disease management due to its efficiency and costeffectiveness, excessive use poses risks to human health and the environment. Botanical fungicides offer advantages such as rapid degradation and low toxicity to mammals, making them increasingly popular for sustainable plant disease control. This study investigated the antifungal properties of Cestrum tomentosum L.f. crude extracts (CTCE) against Colletotrichum scovillei. The results demonstrated that CTCE effectively inhibited conidia germination and germ tube elongation at 40 µg/ml concentrations. Moreover, CTCE exhibited strong antifungal activity against C. scovillei mycelial growth, with an EC50 value of 18.81 µg/ml. In vivo experiments confirmed the protective and curative effects of CTCE on chili pepper fruits infected with C. scovillei. XTT analysis showed that the CTCE could significantly inhibit the cell viability of C. scovillei. Mechanistic studies revealed that CTCE disrupted the plasma membrane integrity of C. scovillei and induced the accumulation of reactive oxygen species in hyphal cells. These findings highlight CTCE as a promising eco-friendly botanical fungicide for managing C. scovillei infections in chili peppers.

Recent advances in nano-enabled immunomodulation for enhancing plant resilience against phytopathogens

Plant diseases caused by microbial pathogens pose a severe threat to global food security. Although genetic modifications can improve plant resistance; however, environmentally sustainable strategies are needed to manage plant diseases. Nano-enabled immunomodulation involves using engineered nanomaterials (ENMs) to modulate the innate immune system of plants and enhance their resilience against pathogens. This emerging approach provides unique opportunities through the ability of ENMs to act as nanocarriers for delivering immunomodulatory agents, nanoprobes for monitoring plant immunity, and nanoparticles (NPs) that directly interact with plant cells to trigger immune responses. Recent studies revealed that the application of ENMs as nanoscale agrochemicals can strengthen plant immunity against biotic stress by enhancing systemic resistance pathways, modulating antioxidant defense systems, activating defense-related genetic pathways and reshaping the plant-associated microbiomes. However, key challenges remain in unraveling the complex mechanisms through which ENMs influence plant molecular networks, assessing their long-term environmental impacts, developing biodegradable formulations, and optimizing targeted delivery methods. This review provides a comprehensive investigation of the latest research on nano-enabled immunomodulation strategies, potential mechanisms of action, and highlights future perspectives to overcome existing challenges for sustainable plant disease management.

Visible-light-driven water-soluble zinc oxide quantum dots for efficient control of citrus canker

BACKGROUND

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is a devastating bacterial disease that reduces citrus yield and quality, posing a serious threat to the citrus industry. Several conventional chemicals have been used to control citrus canker. However, this approach often leads to the excessive use of chemical agents, can exacerbate environmental pollution and promotes the development of resistant Xcc. Therefore, there is significant interest in the development of efficient and environmentally friendly technologies to control citrus canker.

RESULTS

In this study, water-soluble ZnO quantum dots (ZnO QDs) were synthesised as an efficient nanopesticide against Xcc. The results showed that the antibacterial activity of ZnO QDs irradiated with visible light [half-maximal effective concentration (EC50) = 33.18 μg mL-1] was ~3.5 times higher than that of the dark-treated group (EC50 = 114.80 μg mL-1). ZnO QDs induced the generation of reactive oxygen species (•OH, •O- 2 and 1O2) under light irradiation, resulting in DNA damage, cytoplasmic destruction, and decreased catalase and superoxide dismutase activities. Transcription analysis showed downregulation of Xcc genes related to 'biofilms, virulence, adhesion' and 'DNA transfer' exposure to ZnO QDs. More importantly, ZnO QDs also promoted the growth of citrus.

CONCLUSION

This research provides new insights into the photocatalytic antibacterial mechanisms of ZnO QDs and supports the development of more efficient and safer ZnO QDs-based nanopesticides to control citrus canker. © 2024 Society of Chemical Industry.

Silica nanoparticles as a waste product to alleviate the harmful effects of water stress in wheat

Drought is a threat to food security and agricultural sustainability in arid and semi-arid countries. Using wasted silica nanoparticles could minimize water scarcity. A controlled study investigated wheat plant physiological and morphological growth under tap-water irrigation (80-100, 60-80, and 40-60% field capacity). The benefits of S1: 0%, S2: 5%, and S3: 10% nanoparticle silica soil additions were studied. Our research reveals that water stress damages the physiological and functional growth of wheat plants. Plant height decreased by 8.9%, grain yield by 5.4%, and biological yield by 19.2%. These effects were observed when plants were irrigated to 40-60% field capacity vs. control. In plants under substantial water stress (40-60% of field capacity), chlorophyll a (8.04 mg g-1), b (1.5 mg g-1), total chlorophyll (9.55 mg g-1), carotenoids (2.44 mg g-1), and relative water content (54%), Electrolyte leakage (59%), total soluble sugar (1.79 mg g-1 fw), and proline (80.3 mol g-1) were highest. Plants cultivated with silica nanoparticles exhibit better morphological and physiological growth than controls. The largest effect came from maximum silica nanoparticle loading. Silica nanoparticles may increase drought-stressed plant growth and production.

Hollow Mesoporous Silica Nanoparticles as a New Nanoscale Resistance Inducer for Fusarium Wilt Control: Size Effects and Mechanism of Action

In agriculture, soil-borne fungal pathogens, especially Fusarium oxysporum strains, are posing a serious threat to efforts to achieve global food security. In the search for safer agrochemicals, silica nanoparticles (SiO2NPs) have recently been proposed as a new tool to alleviate pathogen damage including Fusarium wilt. Hollow mesoporous silica nanoparticles (HMSNs), a unique class of SiO2NPs, have been widely accepted as desirable carriers for pesticides. However, their roles in enhancing disease resistance in plants and the specific mechanism remain unknown. In this study, three sizes of HMSNs (19, 96, and 406 nm as HMSNs-19, HMSNs-96, and HMSNs-406, respectively) were synthesized and characterized to determine their effects on seed germination, seedling growth, and Fusarium oxysporum f. sp. phaseoli (FOP) suppression. The three HMSNs exhibited no side effects on cowpea seed germination and seedling growth at concentrations ranging from 100 to 1500 mg/L. The inhibitory effects of the three HMSNs on FOP mycelial growth were very weak, showing inhibition ratios of less than 20% even at 2000 mg/L. Foliar application of HMSNs, however, was demonstrated to reduce the FOP severity in cowpea roots in a size- and concentration-dependent manner. The three HMSNs at a low concentration of 100 mg/L, as well as HMSNs-19 at a high concentration of 1000 mg/L, were observed to have little effect on alleviating the disease incidence. HMSNs-406 were most effective at a concentration of 1000 mg/L, showing an up to 40.00% decline in the disease severity with significant growth-promoting effects on cowpea plants. Moreover, foliar application of HMSNs-406 (1000 mg/L) increased the salicylic acid (SA) content in cowpea roots by 4.3-fold, as well as the expression levels of SA marker genes of PR-1 (by 1.97-fold) and PR-5 (by 9.38-fold), and its receptor gene of NPR-1 (by 1.62-fold), as compared with the FOP infected control plants. Meanwhile, another resistance-related gene of PAL was also upregulated by 8.54-fold. Three defense-responsive enzymes of POD, PAL, and PPO were also involved in the HMSNs-enhanced disease resistance in cowpea roots, with varying degrees of reduction in activity. These results provide substantial evidence that HMSNs exert their Fusarium wilt suppression in cowpea plants by activating SA-dependent SAR (systemic acquired resistance) responses rather than directly suppressing FOP growth. Overall, for the first time, our results indicate a new role of HMSNs as a potent resistance inducer to serve as a low-cost, highly efficient, safe and sustainable alternative for plant disease protection.

Silica nanoparticles conferring resistance to bacterial wilt in peanut (Arachis hypogaea L.)

Peanut bacterial wilt (PBW) caused by the pathogen Ralstonia solanacearum severely affects the growth and yield potential of peanut crop. In this study, we synthesized silica nanoparticles (SiO2 NPs), a prospective efficient management approach to control PBW, and conducted a hydroponic experiment to investigate the effects of different SiO2 NPs treatments (i.e., 0, 100, and 500 mg L-1 as NP0, NP100, and NP500, respectively) on promoting plant growth and resistance to R. solanacearum. Results indicated that the disease indices of NP100 and NP500 decreased by 51.5 % and 55.4 % as compared with NP0 under R. solanacearum inoculation, respectively, while the fresh and dry weights and shoot length of NP100 and NP500 increased by 7.62-42.05 %, 9.45-32.06 %, and 2.37-17.83 %, respectively. Furthermore, SiO2 NPs induced an improvement in physio-biochemical enzymes (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and lipoxygenase) which eliminated the excess production of hydrogen peroxide, superoxide anions, and malondialdehyde to alleviate PBW stress. Notably, the targeted metabolomic analysis indicated that SiO2 NPs enhanced salicylic acid (SA) contents, which involved the induction of systemic acquired resistance (SAR). Moreover, the transcriptomic analysis revealed that SiO2 NPs modulated the expression of multiple transcription factors (TFs) involved in the hormone pathway, such as AHLs, and the identification of hormone pathways related to plant defense responses, such as the SA pathway, which activated SA-dependent defense mechanisms. Meanwhile, the up-regulated expression of the SA-metabolism gene, salicylate carboxymethyltransferase (SAMT), initiated SAR to promote PBW resistance. Overall, our findings revealed that SiO2 NPs, functioning as a plant elicitor, could effectively modulate physiological enzyme activities and enhance SA contents through the regulation of SA-metabolism genes to confer the PBW resistance in peanuts, which highlighted the potential of SiO2 NPs for sustainable agricultural practices.

Biosynthesis of high antibacterial silver chloride nanoparticles against Ralstonia solanacearum using spent mushroom substrate extract

In this study, a green and highly efficient method was proposed to synthesize nano-silver chloride (nano-AgCl) using spent mushroom substrate (SMS) extract as a cheap reactant. Nanoparticles were characterized by a series of techniques like x-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), which showed the formation of near-spherical silver chloride nanoparticles with an average size of about 8.30 nm. Notably, the synthesized nano-silver chloride has a more prominent antibacterial effect against Ralstonia solanacearum (EC50 = 5.18 mg L−1) than non-nano-sized silver chloride particles, nano-silver chloride synthesized by chemical method, and commercial pesticides. In-depth, the study of the mechanism revealed that nano-silver chloride could cause cell membrane disruption, DNA damage and intracellular generation of reactive oxygen species (·OH, ·O2− and 1O2), leading to peroxidation damage in Ralstonia solanacearum (R. solanacearum). Moreover, the reaction between nano-silver chloride and bacteria could be driven by intermolecular forces instead of electrostatic interactions. Our study provides a new approach to synthesizing nano-silver chloride as a highly efficient antibacterial agent and broadens the utilization of agricultural waste spent mushroom substrate.

Liquid crystal monomers in ventilation and air conditioning dust: Indoor characteristics, sources analysis and toxicity assessment

Indoor dust contaminated with liquid crystal monomers (LCMs) released from various commercial liquid crystal display (LCD) screens may pose environmental health risks to humans. This study aimed to investigate the occurrence of 64 LCMs in ventilation and air conditioning filters (VACF) dust, characterize their composition profiles, potential sources, and associations with indoor characteristics, and assess their in vitro toxicity using the human lung bronchial epithelial cells (BEAS-2B). A total of 31 LCMs with concentrations (ΣLCMs) ranging from 43.7 ng/g to 448 ng/g were detected in the collected VACF dust. Additional analysis revealed the potential interactions between indoor environmental conditions and human exposure risks associated with the detected LCMs in VACF dust. The service area and working time of the ventilation and air conditioning system, and the number of indoor LCD screens were positively correlated with the fluorinated ΣLCMs in VACF dust (r = 0.355 ∼ 0.511, p < 0.05), while the associations with the non-fluorinated ΣLCMs were not found (p > 0.05), suggesting different environmental behavior and fates of fluorinated and non-fluorinated LCMs in the indoor environment. Four main indoor sources of LCMs (i.e., computer (37.1%), television (28.3%), Brand A smartphone (21.2%) and Brand S smartphone (13.4%)) were identified by positive matrix factorization-multiple linear regression (PMF-MLR). Exposure to 14 relatively frequently detected LCMs, individually and in the mixture, induced significant oxidative stress in BEAS-2B cells. Among them, non-fluorinated LCMs, specifically 3cH2B and MeP3bcH, caused dominant decreased cell viability. This study provides new insights into the indoor LCMs pollution and the associated potential health risks due to the daily use of electronic devices.