Star Polymer Size, Charge Content, and Hydrophobicity Affect their Leaf Uptake and Translocation in Plants

A self-assembled multicomponent RNA nano-biopesticide for increasing the susceptibility of destructive bean flower thrips to insecticides via dsNrf2

High resistance of bean flower thrips (BFT, Megalurothrips usitatus) has led to the unscientific application of insecticides to cause famous "toxic cowpea" incidents in China. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in inducing antioxidant responses and drug detoxification. Therefore, the detoxification genes may be suppressed to control insecticide resistance via Nrf2. Herein, we demonstrated that the expression of most detoxification genes and enzyme activity were remarkably suppressed via nrf2 RNAi. Subsequently, a novel hydrophilic-lipophilic diblock polymer (HLDP) was developed to co-assemble with dsNrf2 and sulfoxaflor (SUL) into nanoscale SUL/HLDP/dsNrf2 complex (221.52 nm). Excitingly, the SUL/HLDP/dsNrf2 complex exhibited excellent leaf adhesion performance, with the smaller contact angle, reduced surface tension, amplified contact area, improved retention, and enhanced plant uptake. Meanwhile, theSUL/HLDP/dsNrf2 displayed high delivery efficiency in vitro and in vivo, and its insecticidal activity against BFTs was significantly higher than SUL. Furthermore, the required doses of SUL/HLDP/dsNrf2 to achieve similar insecticidal activity were 50.14% and 58.42% of SUL via immersion and oral feeding, respectively. Overall, this study elucidated the regulatory role of nrf2 in the detoxification and metabolism of BFTs and developed a self-assembled multicomponent RNA nano-biopesticide to increase the susceptibility of BFTs to insecticides.

Chitosan Coating as a Strategy to Increase Postemergent Herbicidal Efficiency and Alter the Interaction of Nanoatrazine with Bidens pilosa Plants

The atrazine nanodelivery system, composed of poly(ε-caprolactone) (PCL+ATZ) nanocapsules (NCs), has demonstrated efficient delivery of the active ingredient to target plants in previous studies, leading to greater herbicide effectiveness than conventional formulations. Established nanosystems can be enhanced or modified to generate new biological activity patterns. Therefore, this study aimed to evaluate the effect of chitosan coating of PCL+ATZ NCs on herbicidal activity and interaction mechanisms with Bidens pilosa plants. Chitosan-coated NCs (PCL/CS+ATZ) were synthesized and characterized for size, zeta potential, polydispersity, and encapsulation efficiency. Herbicidal efficiency was assessed in postemergence greenhouse trials, comparing the effects of PCL/CS+ATZ NCs (coated), PCL+ATZ NCs (uncoated), and conventional atrazine (ATZ) on photosystem II (PSII) activity and weed control. Using a hydroponic system, we evaluated the root absorption and shoot translocation of fluorescently labeled NCs. PCL/CS+ATZ presented a positive zeta potential (25 mV), a size of 200 nm, and an efficiency of atrazine encapsulation higher than 90%. The postemergent herbicidal activity assay showed an efficiency gain of PSII activity inhibition of up to 58% compared to ATZ and PCL+ATZ at 96 h postapplication. The evaluation of weed control 14 days after application ratified the positive effect of chitosan coating on herbicidal activity, as the application of PCL/CS+ATZ at 1000 g of a.i. ha-1 resulted in better control than ATZ at 2000 g of a.i. ha-1 and PCL+ATZ at 1000 g of a.i. ha-1. In the hydroponic experiment, chitosan-coated NCs labeled with a fluorescent probe accumulated in the root cortex, with a small quantity reaching the vascular cylinder and leaves up to 72 h after exposure. This behavior resulted in lower leaf atrazine levels and PSII inhibition than ATZ. In summary, chitosan coating of nanoatrazine improved the herbicidal activity against B. pilosa plants when applied to the leaves but negatively affected the root-to-shoot translocation of the herbicide. This study opens avenues for further investigations to improve and modify established nanosystems, paving the way for developing novel biological activity patterns.

Quantum chemically calculated Abraham parameters for quantifying and predicting polymer hydrophobicity

The leakage and accumulation of plastic in the environment is a significant and growing problem with numerous detrimental impacts and has led to a push toward the design and development of more environmentally benign materials. To this end, we have developed a quantum chemistry-based model for predicting the mobility of polymer materials from molecular structure. Hydrophobicity is used as a surrogate for mobility given that hydrophobic interactions drive much of the partitioning of contaminants in and out of various environmentally relevant compartments. To model polymer hydrophobicity, we adjusted a previously developed Quantum Chemically Calculated Abraham Parameter model to calculate Abraham parameters of small molecules from molecular structure information. The resulting model predicted the octanol-water partition coefficient (KOW) of polymer repeating units with a root mean square error (RMSE) of 0.48 (log scale). Additionally, the hydrophobicity of high molecular weight polymer materials was captured through solubility parameters and Nile red staining experiments from the literature and predicted with RMSEs of 1.21 (J/cc)0.5 and 3.42 nm, respectively. Finally, to test the environmental applicability of the model, the relative adsorption capacity of three polymers was predicted and used to unify sorption isotherms across multiple sorbates and polymer sorbents.

Developing frameworks for nanotechnology-driven DNA-free plant genome-editing

The bottlenecks of conventional plant genome-editing methods gave an innovative rise to nanotechnology as a delivery tool to manipulate gene(s) of interest. Studies suggest a strong correlation between the physicochemical properties of nanomaterials and their efficiency in gene delivery to different plant species/tissues. In this opinion article we highlight the need for a deeper understanding of plant-nanomaterial interactions to align their full capabilities with the strategic goals of plant genome-editing. Additionally, we emphasize DNA-free plant genome-editing approaches to potentially mitigate concerns surrounding genetically modified organisms (GMOs). Lastly, we propose a strategic integration of the principles of responsible research and innovation (RRI) in R&D. We aim to initiate a dialogue on developing collaborative and socio-technical frameworks for nanotechnology and DNA-free plant genome-editing.

Visual tracking of engineered nanomaterials-facilitated pesticide absorption and translocation in plants

Visualizing the movement of pesticides carried by engineered nanoparticles within plants is vital for understanding their behavior. This research presents a novel visualization technique for intuitively monitoring the manner of nanocarriers delivering pesticides to plants. Using in situ surface-enhanced Raman spectroscopy (SERS) imaging analysis, the performance of engineered nanomaterials (ENMs) as carriers to enhance the transdermal transport of pesticides on plant leaves was successfully evaluated. The hydrophilic nature of polyvinylpyrrolidone (PVP) was observed to facilitate the stable adsorption of ENMs such as gold nanoparticles (Au NPs) on the hydrophilic molecules or functional groups on the leaf surface. Additionally, the gold-sulfur bond between Au NPs and dimethoate enhanced the adhesion and absorption of the pesticide by the plant. Notably, the small-sized Au NPs-dimethoate complex exhibited greater penetration depth and velocity compared to its larger counterpart. The uneven distribution of the Au NPs-dimethoate complex across the leaf cross-section was influenced by the physical structure. Overall, the penetrating capacity of Au NPs on plant leaves played a crucial role in enhancing the effective delivery of dimethoate, increasing both the adsorption capacity and penetration rate. This advancement results in a reduction in the quantity of pesticide applied, fundamentally mitigating the environmental pollution and aligning with environmental conservation objectives.

High Aspect Ratio Polymer Nanocarriers for Gene Delivery and Expression in Plants

Plant genetic engineering methods are critical for food security and biofuel production and to enable molecular farming. Here, we elucidated how polymeric high aspect ratio nanocarriers can enable DNA delivery to Nicotiana benthamiana plants and transient expression. We demonstrated that a nanocarrier with 20 nm width, 80 nm length, and a polymer-to-DNA ratio of N/P = 3.0 afforded the most efficient DNA delivery and expression among the parameter space investigated. Additionally, we showed that polymer-DNA complexes with a moderate positive charge of ∼14 mV favored penetration through the cell wall and membranes with the assistance of cell wall degrading enzymes. Together, these results establish a narrow window of aspect ratios and charges of the nanocarrier-DNA complex that enables DNA delivery to plants using polymeric nanocarriers. This fundamental nanocarrier structure-function relationship informs the design of soft-material nanocarriers for nucleic acid delivery in plant cells to facilitate a wide range of plant biotechnology applications.

Improving Soybean Germination and Nodule Development with Nitric Oxide-Releasing Polymeric Nanoparticles

Nitric oxide (NO) is a multifunctional signaling molecule in plants, playing key roles in germination, microbial symbiosis, and nodule formation. However, its instability requires innovative approaches, such as using nanoencapsulated NO donors, to prolong its effects. This study evaluated the impact of treating soybean (Glycine max) seeds with the NO donor S-nitrosoglutathione (GSNO), encapsulated in polymeric nanoparticles, on the germination, nodulation, and plant growth. Seeds were treated with free GSNO, chitosan nanoparticles with/without NO (NP CS-GSNO/NP CS-GSH, where GSH is glutathione, the NO donor precursor), and alginate nanoparticles with/without NO (NP Al-GSNO/NP Al-GSH). Chitosan nanoparticles (positive zeta potential) were smaller and released NO faster compared with alginate nanoparticles (negative zeta potential). The seed treatment with NP CS-GSNO (1 mM, related to GSNO concentration) significantly improved germination percentage, root length, number of secondary roots, and dry root mass of soybean compared with the control. Conversely, NP CS-GSH resulted in decreased root and shoot length. NP Al-GSNO enhanced shoot dry mass and increased the number of secondary roots by approximately threefold at the highest concentrations. NP CS-GSNO, NP Al-GSNO, and NP Al-GSH increased S-nitrosothiol levels in the roots by approximately fourfold compared with the control. However, NP CS-GSNO was the only treatment that increased the nodule dry mass of soybean plants. Therefore, our results indicate the potential of chitosan nanoparticles to improve the application of NO donors in soybean seeds.

Light-emitting probes for in situ sensing of plant information

Monitoring plant physiological information for gaining a comprehensive understanding of plant growth and stress responses contributes to safeguarding plant health. Light-emitting probes - in terms of small-molecule, nanomaterials-based, and genetically protein-based probes - can be introduced into plants through foliar and root treatment or genetic transformation. These probes offer exciting opportunities for sensitive and in situ monitoring of dynamic plant chemical information - for example, reactive oxygen species (ROS), calcium ions, phytohormones - with spatiotemporal resolution. In this review we explore the sensing mechanisms of these light-emitting probes and their applications in monitoring various chemical information in plants in situ. These probes can be used as part of a sentinel plant approach to provide stress warning in the field or to explore plant signaling pathways.

Crystal structure of Kunitz-type trypsin inhibitor: Entomotoxic effect of native and encapsulated protein targeting gut trypsin of Tribolium castaneum Herbst

Trypsin inhibitors are known to act against insect pests by inhibiting proteases of the digestive tract. In this study, we report structural and functional characterization of ∼ 19 kDa Albizia procera Kunitz-type trypsin inhibitor (ApKTI) protein with potential bio-insecticidal applications. Crystal structure of ApKTI protein has been refined to 1.42 Å and molecular structure (8HNR) showed highly beta sheeted conformation including 12 beta sheets, 15 loops and two small alpha helices. Docking between predicted model of Tribolium castaneum trypsin (TcPT) and 8HNR produced a stable complex (-11.3 kcal/mol) which reflects the inhibitory potential of ApKTI against insect gut trypsin. Significant mortality was observed in all life stages of T. castaneum including egg, larvae, pupae and adults with a 3.0 mg native ApKTI treatment in comparison to negative control. Although standard trypsin inhibitor (Glycine max trypsin inhibitors; GmKTI; 3.0 mg) produced maximum reduction against all above life stages; however, a non-significant mortality difference was observed in comparison to 3.0 mg native ApKTI. The study further explores the synthesis and characterization of Graphene (GNPs) and Zinc oxide (ZnONPs) nanoparticles, followed by the optimization of ApKTI and GmKTI loading on both nanoparticles to evaluate their enhanced insecticidal effectiveness. Encapsulated proteins showed significant mortality against T. castaneum across all concentrations, with GNPs proving more effective than ZnONPs. Additionally, encapsulated GmKTI produced significant mortality of eggs compared to loaded ApKTI treatments while other life stages were non-significantly affected by two proteins. This research highlights the importance of encapsulated ApKTI protein for eco-friendly pest management strategies.

Differential Leaf-to-Root Movement, Trophic Transfer, and Tissue-Specific Biodistribution of Metal-Based and Polymer-Based Nanoparticles When Present Singly and in Mixture

The transfer of nanoparticles (NPs) through the terrestrial food chain via foliar uptake presents poorly understood risks, especially in scenarios involving copollution and plant translocation. Herein, we exposed the radishes to single and mixed foliar doses of CeO2 NPs and deuterated polystyrene (DPS), investigating the trophic transfer of NPs from radish shoots/roots to snails. Compared to single treatments, mixture treatments increased Ce uptake by plants but had no effect on DPS uptake. Additionally, mixture treatments did not affect the movement of Ce and DPS from shoots to roots. Under NP mixture exposure, trophic transfer efficiencies (TTF) for Ce (2.09 × 10-2) and DPS (2.54 × 10-2) significantly decreased in shoot-feeding snails. In root-feeding snails, TTF for Ce (3.32 × 10-1) also showed a significant decrease, while TTF for DPS remained unchanged. Mixture treatments exhibited differential impacts on different snail body parts, particularly leading to biomagnification of DPS in the digestive glands and soft tissues (TTF > 1) of snails consuming roots exposed to mixtures. Both CeO2 and DPS displayed a sudden increase in assimilation efficiency following translocation to the roots. This study provides insights into changes during trophic transfer due to coexposure and plant translocation processes associated with nanoparticles, enhancing our comprehension regarding their environmental risks.

Controlled Fabrication of Unimolecular Micelles as Versatile Nanoplatform for Multifunctional Applications

Unimolecular micelles (UMs) are nano-sized structures that are composed of single molecules with precise composition. Compared to self-assembled polymeric micelles, UMs possess ultra-stable property even in complex biological environment. With the development of controllable polymerization and coupling chemistry, the preparation of narrowly monodispersed UMs with precise morphology and size has been realized, which further facilitates their multifunctional applications. After brief introduction, state-of-the-art advances in the synthesis and applications of UMs are discussed with an emphasis on their bioapplications. It is believed that these UMs have great potential in future fabrication of multifunctional nanoplatforms.

GABA-Decorated Nanocarrier for Smart Delivery of Fludioxonil for Targeted Control of Banana Wilt Disease

Developing a targeted nanopesticide to control the vascular disease of banana in agriculture is crucial to improve pesticide utilization. In this study, according to the degree of functionalization, three γ-aminobutyric acid (GABA)-decorated nanocarriers (PSI-GABA8, PSI-GABA18, and PSI-GABA28) were constructed for smart delivery of nonsystemic fungicide in banana phloem tissues. Fludioxonil (Flu) was loaded in nanocarriers to form Flu@PSI-GABA nanoparticles with a core/shell structure for control of banana wilt disease. Results demonstrated that the delivery dosage of Flu was up to 1.6 mg/L in castor phloem sap using PSI-GABA28 nanocarriers. In vitro results showed that the EC50 of Flu@PSI-GABA28 was 0.0116 mg/L, and the inhibitory activity was about 8.8 times higher than that of technical-grade (TC) Flu. Flu@PSI-GABA28 could be transported for long distances and accumulated to the rhizome of banana by foliar application, and the control effectiveness was about 20 times that of the conventional Flu (50% WP) for the banana wilt. This study provides a distinctive guidance for effective control of vascular diseases in precision agriculture application.

Polymeric Nanocarriers Autonomously Cross the Plant Cell Wall and Enable Protein Delivery for Stress Sensing

Delivery of proteins in plant cells can facilitate the design of desired functions by modulation of biological processes and plant traits but is currently limited by narrow host range, tissue damage, and poor scalability. Physical barriers in plants, including cell walls and membranes, limit protein delivery to desired plant tissues. Herein, a cationic high aspect ratio polymeric nanocarriers (PNCs) platform is developed to enable efficient protein delivery to plants. The cationic nature of PNCs binds proteins through electrostatic. The ability to precisely design PNCs' size and aspect ratio allowed us to find a cutoff of ≈14 nm in the cell wall, below which cationic PNCs can autonomously overcome the barrier and carry their cargo into plant cells. To exploit these findings, a reduction-oxidation sensitive green fluorescent protein (roGFP) is deployed as a stress sensor protein cargo in a model plant Nicotiana benthamiana and common crop plants, including tomato and maize. In vivo imaging of PNC-roGFP enabled optical monitoring of plant response to wounding, biotic, and heat stressors. These results show that PNCs can be precisely designed below the size exclusion limit of cell walls to overcome current limitations in protein delivery to plants and facilitate species-independent plant engineering.

Foliar Uptake and Distribution of Metallic Oxide Nanoparticles in Maize (Zea mays L.) Leaf

The foliar uptake of Fe3O4, Cr2O3, CuO, and ZnO nanoparticles (NPs) by maize (Zea mays L.) was studied in a lab-scale experiment. The significant increase of Fe concentrations in leaves exposed to Fe3O4 was observed in both stomatal closing and stomatal opening treatments, suggesting the presence of a nonstomatal uptake. In parallel treatments with equal doses of Fe3O4 (∼200 nm), Cr2O3 (∼300 nm), CuO (∼30 nm), and ZnO (∼40 nm) (20-200 μg), the retention percentage of Fe in the leaves (21.0-69.0%) was higher than that of Cr, Cu, and Zn (0.5-14.0%). The steric hindrance effect seems more important for NPs of >200 nm, while hydrophobic surface and negative charge promote the foliar uptake of NPs smaller than 200 nm. The accumulation of NPs in the cuticle was observed through dark-field hyperspectral microscopy. Cr2O3, Fe3O4, and CuO NPs were difficult to penetrate the cuticle. In comparison, ZnO further migrated and distributed within the extracellular space of epidermal and mesophyll cells of the exposed leaf, possibly due to its comparatively higher solubility and hydrophilicity. The findings highlight the potential of the nonstomatal uptake, which might be a critical route for metallic oxide NPs to enter the food chain.

Dynamical Adsorption Behavior Prediction of Dried Tobacco Leaf Heterogeneous Interfaces through Simulation and Image Recognition Techniques

The process of spraying water and flavorings on dry tobacco is an important factor in the industrial environment and product quality. Tobacco as a complex porous fiber material, the interfacial transfer process of water is complex. In this study, machine learning and image recognition techniques were utilized to quickly obtain the structural parameters of the tobacco surface and construct a cellular structure model of the tobacco surface. In situ observation of the droplet impact spreading process was carried out using a high-speed camera to explore the droplet dissipation dynamics on different surfaces. And the competing processes of droplet wetting and evaporation under the influence of surface microstructure were determined by combining experimental studies and finite element simulation calculations. Based on the characteristics of tobacco pore size distribution, the infiltration under gas-liquid two-phase action was transformed into single-phase flow transfer under capillary force, and the continuous droplet infiltration process was simulated. A parallel artificial membrane permeability measurement method of bionic tobacco waxy layer was constructed for the screening of spray dosing copenetrant. This study brings new insights into the wetting of porous fibrous materials and is important for exploring the wetting process and additive development process influenced by the microstructure.

Towards realizing nano-enabled precision delivery in plants

Nanocarriers (NCs) that can precisely deliver active agents, nutrients and genetic materials into plants will make crop agriculture more resilient to climate change and sustainable. As a research field, nano-agriculture is still developing, with significant scientific and societal barriers to overcome. In this Review, we argue that lessons can be learned from mammalian nanomedicine. In particular, it may be possible to enhance efficiency and efficacy by improving our understanding of how NC properties affect their interactions with plant surfaces and biomolecules, and their ability to carry and deliver cargo to specific locations. New tools are required to rapidly assess NC-plant interactions and to explore and verify the range of viable targeting approaches in plants. Elucidating these interactions can lead to the creation of computer-generated in silico models (digital twins) to predict the impact of different NC and plant properties, biological responses, and environmental conditions on the efficiency and efficacy of nanotechnology approaches. Finally, we highlight the need for nano-agriculture researchers and social scientists to converge in order to develop sustainable, safe and socially acceptable NCs.

Redox/pH Dual-Responsive Fluorescent Nanoparticles for Intelligent Pesticide Release and Visualization in Gray Mold Disease Synergistic Control

An intelligent delivery nanoformulation could enhance the utilization efficacy, uptake, and translocation of pesticides in plants. Herein, a redox/pH-triggered and fluorescent smart delivery nanoformulation was designed and constructed by using hollow mesoporous organosilica nanoparticles (HMONs) and ZnO quantum dots as the nanocarrier and capping agent, respectively. Boscalid was further loaded to generate Boscalid@HMONs@ZnO with a loading rate of 9.8% for controlling Botrytis cinerea (B. cinerea). The quantity of boscalid released by Boscalid@HMONs@ZnO in a glutathione environment or at pH 3.0 was 1.3-fold and 1.9-fold higher than that in a neutral condition. Boscalid@HMONs@ZnO has 1.7-fold the toxicity index of boscalid technical against B. cinerea in antifungal experiments. Pot experiments revealed that the efficacy of Boscalid@HMONs@ZnO was significantly enhanced more than 1.27-fold compared to commercially available water-dispersible granules of boscalid. Due to the fluorescence properties of Boscalid@HMONs@ZnO, pesticide transport's real-time monitoring of pesticide translocation in tomato plants could be observed by confocal laser scanning microscopy. Fluorescence images revealed that HMONs@ZnO had been effectively transported via treated leaves or roots in tomato plants. This research showed the successful application of HMONs@ZnO as a nanocarrier for controlling disease and offered an effective avenue to explore the real-time tracking of pesticide translocation in plants.

Carbon Nanodot-Microbe-Plant Nexus in Agroecosystem and Antimicrobial Applications

The intensive applications of nanomaterials in the agroecosystem led to the creation of several environmental problems. More efforts are needed to discover new insights in the nanomaterial-microbe-plant nexus. This relationship has several dimensions, which may include the transport of nanomaterials to different plant organs, the nanotoxicity to soil microbes and plants, and different possible regulations. This review focuses on the challenges and prospects of the nanomaterial-microbe-plant nexus under agroecosystem conditions. The previous nano-forms were selected in this study because of the rare, published articles on such nanomaterials. Under the study's nexus, more insights on the carbon nanodot-microbe-plant nexus were discussed along with the role of the new frontier in nano-tellurium-microbe nexus. Transport of nanomaterials to different plant organs under possible applications, and translocation of these nanoparticles besides their expected nanotoxicity to soil microbes will be also reported in the current study. Nanotoxicity to soil microbes and plants was investigated by taking account of morpho-physiological, molecular, and biochemical concerns. This study highlights the regulations of nanotoxicity with a focus on risk and challenges at the ecological level and their risks to human health, along with the scientific and organizational levels. This study opens many windows in such studies nexus which are needed in the near future.

Critical Review: Uptake and Translocation of Organic Nanodelivery Vehicles in Plants

Nanodelivery vehicles (NDVs) are engineered nanomaterials (ENMs) that, within the agricultural sector, have been investigated for their ability to improve uptake and translocation of agrochemicals, control release, or target specific tissues or subcellular compartments. Both inorganic and organic NDVs have been studied for agrochemical delivery in the literature, but research on the latter has been slower to develop than the literature on the former. Since the two classes of nanomaterials exhibit significant differences in surface chemistry, physical deformability, and even colloidal stability, trends that apply to inorganic NDVs may not hold for organic NDVs, and vice versa. We here review the current literature on the uptake, translocation, biotransformation, and cellular and subcellular internalization of organic NDVs in plants following foliar or root administration. A background on nanomaterials and plant physiology is provided as a leveling ground for researchers in the field. Trends in uptake and translocation are examined as a function of NDV properties and compared to those reported for inorganic nanomaterials. Methods for assessing fate and transport of organic NDVs in plants (a major bottleneck in the field) are discussed. We end by identifying knowledge gaps in the literature that must be understood in order to rationally design organic NDVs for precision agrochemical nanodelivery.

Foliar application of glycine-functionalized nanopesticides for effective prevention and control of root-knot nematodes via a targeted delivery strategy

BACKGROUND

Root-knot nematodes (RKNs) are the highly damaging pests for various crops, and the prevalence of RKNs has posed serious threats to worldwide agricultural harvest, severely affecting global food security and ecosystem health. Traditional pesticide systems on controlling RKNs generally cause environmental hazards and phytotoxicity due to the excessive use of pesticides resulted from low utilization efficiency. And effective approaches with biosafe and efficient features are highly demanded to break away from the dilemma caused by RKNs.

RESULTS

In this research, a nanopesticide system with root-targeted delivery function was developed to achieve effective prevention and control of RKNs. The nanocarriers (MSN-KH560-Gly) and the obtained nanopesticides (EB@MSN-KH560-Gly) were proved to be biosafe. Also, this nanopesticide system demonstrated sustained release behavior. The grafting of glycine (Gly) significantly improved the pesticide contents translocating to cucumber roots (about 304.7%). Besides, such root-targeted delivery function resulted in no root nodule in cucumber plants after the foliar application of these nanopesticides (prevention rate of 100%). In addition, the root nodule numbers of the infected cucumber plants decreased by 71.67%.

CONCLUSION

Foliar application of these Gly-functionalized nanopesticides achieved effective prevention and control of RKNs due to the root-targeted delivery property inherent in this nanopesticide system, and such root-targeted delivery strategy opens a novel and efficient method to protect crops from RKN invasion and thus facilitates the development of sustainable agriculture. © 2023 Society of Chemical Industry.

Uptake, accumulation and translocation mechanisms of organophosphate esters in cucumber (Cucumis sativus) following foliar exposure

Organophosphate esters (OPEs) have been frequently detected in crops. However, few studies have focused on the uptake and translocation of OPEs in plants following foliar exposure. Herein, to investigate the foliar uptake, accumulation and translocation mechanisms of OPEs in plant, the cucumber (Cucumis sativus) was selected as a model plant for OPEs exposure via foliar application under control conditions. The results showed that the content of OPEs in the leaf cuticle was higher than that in the mesophyll on exposed leaf. Significant positive correlations were observed between the content of OPEs in the leaf cuticle and their log Kow and log Kcw values (P < 0.01), suggesting that OPEs with high hydrophobicity could not easily move from the cuticle to the mesophyll. The moderately hydrophobic OPEs, such as tris (2-chloroisopropyl) phosphate (TCPP, log Kow = 2.59), were more likely to move not only from the cuticle to the mesophyll but also from the mesophyll to the phloem. The majority of the transported OPEs accumulated in younger leaves (32-45 %), indicating that younger tissue was the primary target organ for OPEs accumulation after foliar exposure. Compared to chlorinated OPEs (except TCPP) and aryl OPEs, alkyl OPEs exhibited the strongest transport capacity in cucumber seedling due to their high hydrophilicity. Interestingly, tri-p-cresyl phosphate was found to be more prone to translocation compared to tri-m-cresyl phosphate and tri-o-cresyl phosphate, despite having same molecular weight and similar log Kow value. These results can contribute to our understanding of foliar uptake and translocation mechanism of OPEs by plant.

Effect of a Zinc Phosphate Shell on the Uptake and Translocation of Foliarly Applied ZnO Nanoparticles in Pepper Plants (Capsicum annuum)

Here, isotopically labeled 68ZnO NPs (ZnO NPs) and 68ZnO NPs with a thin 68Zn3(PO4)2 shell (ZnO_Ph NPs) were foliarly applied (40 μg Zn) to pepper plants (Capsicum annuum) to determine the effect of surface chemistry of ZnO NPs on the Zn uptake and systemic translocation to plant organs over 6 weeks. Despite similar dissolution of both Zn-based NPs after 3 weeks, the Zn3(PO4)2 shell on ZnO_Ph NPs (48 ± 12 nm; -18.1 ± 0.6 mV) enabled a leaf uptake of 2.31 ± 0.34 μg of Zn, which is 2.7 times higher than the 0.86 ± 0.18 μg of Zn observed for ZnO NPs (26 ± 8 nm; 14.6 ± 0.4 mV). Further, ZnO_Ph NPs led to higher Zn mobility and phloem loading, while Zn from ZnO NPs was stored in the epidermal tissues, possibly through cell wall immobilization as a storage strategy. These differences led to higher translocation of Zn from the ZnO_Ph NPs within all plant compartments. ZnO_Ph NPs were also more persistent as NPs in the exposed leaf and in the plant stem over time. As a result, the treatment of ZnO_Ph NPs induced significantly higher Zn transport to the fruit than ZnO NPs. As determined by spICP-TOFMS, Zn in the fruit was not in the NP form. These results suggest that the Zn3(PO4)2 shell on ZnO NPs can help promote the transport of Zn to pepper fruits when foliarly applied. This work provides insight into the role of Zn3(PO4)2 on the surface of ZnO NPs in foliar uptake and in planta biodistribution for improving Zn delivery to edible plant parts and ultimately improving the Zn content in food for human consumption.

Targeted Delivery of Sucrose-Coated Nanocarriers with Chemical Cargoes to the Plant Vasculature Enhances Long-Distance Translocation

Current practices for delivering agrochemicals are inefficient, with only a fraction reaching the intended targets in plants. The surfaces of nanocarriers are functionalized with sucrose, enabling rapid and efficient foliar delivery into the plant phloem, a vascular tissue that transports sugars, signaling molecules, and agrochemicals through the whole plant. The chemical affinity of sucrose molecules to sugar membrane transporters on the phloem cells enhances the uptake of sucrose-coated quantum dots (sucQD) and biocompatible carbon dots with β-cyclodextrin molecular baskets (suc-β-CD) that can carry a wide range of agrochemicals. The QD and CD fluorescence emission properties allowed detection and monitoring of rapid translocation (<40 min) in the vasculature of wheat leaves by confocal and epifluorescence microscopy. The suc-β-CDs more than doubled the delivery of chemical cargoes into the leaf vascular tissue. Inductively coupled plasma mass spectrometry (ICP-MS) analysis showed that the fraction of sucQDs loaded into the phloem and transported to roots is over 6.8 times higher than unmodified QDs. The sucrose coating of nanoparticles approach enables unprecedented targeted delivery to roots with ≈70% of phloem-loaded nanoparticles delivered to roots. The use of plant biorecognition molecules mediated delivery provides an efficient approach for guiding nanocarriers containing agrochemicals to the plant vasculature and whole plants.

Toxicity Mechanisms of Nanoplastics on Crop Growth, Interference of Phyllosphere Microbes, and Evidence for Foliar Penetration and Translocation

Despite the increasing prevalence of atmospheric nanoplastics (NPs), there remains limited research on their phytotoxicity, foliar absorption, and translocation in plants. In this study, we aimed to fill this knowledge gap by investigating the physiological effects of tomato leaves exposed to differently charged NPs and foliar absorption and translocation of NPs. We found that positively charged NPs caused more pronounced physiological effects, including growth inhibition, increased antioxidant enzyme activity, and altered gene expression and metabolite composition and even significantly changed the structure and composition of the phyllosphere microbial community. Also, differently charged NPs exhibited differential foliar absorption and translocation, with the positively charged NPs penetrating more into the leaves and dispersing uniformly within the mesophyll cells. Additionally, NPs absorbed by the leaves were able to translocate to the roots. These findings provide important insights into the interactions between atmospheric NPs and crop plants and demonstrate that NPs' accumulation in crops could negatively impact agricultural production and food safety.

Metagenomic and proteomic insights into the self-adaptive cell surface hydrophobicity of Sphingomonas sp. strain PAH02 reducing the migration of cadmium-phenanthrene co-pollutant in rice

Cell surface hydrophobicity (CSH) dominates the interactions between rhizobacteria and pollutants at the soil-water interface, which is critical for understanding the dissipation of pollutants in the rhizosphere microzone of rice. Herein, we explored the effects of self-adaptive CSH of Sphingomonas sp. strain PAH02 on the translocation and biotransformation behaviour of cadmium-phenanthrene (Cd-Phe) co-pollutant in rice and rhizosphere microbiome. We evidenced that strain PAH02 reduced the adsorption of Cd-Phe co-pollutant on the rice root surface while enhancing the degradation of Phe and adsorption of Cd via its self-adaptive CSH in the hydroponic experiment. The significant upregulation of key protein expression levels such as MerR, ARHDs and enoyl-CoA hydratase/isomerase, ensures self-adaptive CSH to cope with the stress of Cd-Phe co-pollutant. Consistently, the bioaugmentation of strain PAH02 promoted the formation of core microbiota in the rhizosphere soil of rice (Oryza sativa L.), such as Bradyrhizobium and Streptomyces and induced gene enrichment of CusA and PobA that are strongly associated with pollutant transformation. Consequently, the contents of Cd and Phe in rice grains at maturity decreased by 17.2% ± 0.2% and 65.7% ± 0.3%, respectively, after the bioaugmentation of strain PAH02. These findings present new opportunities for the implementation of rhizosphere bioremediation strategies of co-contaminants in paddy fields.

Nanoenabled Enhancement of Plant Tolerance to Heat and Drought Stress on Molecular Response

Global warming has posed significant pressure on agricultural productivity. The resulting abiotic stresses from high temperatures and drought have become serious threats to plants and subsequent global food security. Applying nanomaterials in agriculture can balance the plant's oxidant level and can also regulate phytohormone levels and thus maintain normal plant growth under heat and drought stresses. Nanomaterials can activate and regulate specific stress-related genes, which in turn increase the activity of heat shock protein and aquaporin to enable plants' resistance against abiotic stresses. This review aims to provide a current understanding of nanotechnology-enhanced plant tolerance to heat and drought stress. Molecular mechanisms are explored to see how nanomaterials can alleviate abiotic stresses on plants. In comparison with organic molecules, nanomaterials offer the advantages of targeted transportation and slow release. These advantages help the nanomaterials in mitigating drought and heat stress in plants.

Application of ZnO Nanoparticles Encapsulated in Mesoporous Silica on the Abaxial Side of a Solanum lycopersicum Leaf Enhances Zn Uptake and Translocation via the Phloem

Foliar application of nutrient nanoparticles (NPs) is a promising strategy for improving fertilization efficiency in agriculture. Phloem translocation of NPs from leaves is required for efficient fertilization but is currently considered to be feasible only for NPs smaller than a cell wall pore size exclusion limit of <20 nm. Using mass spectrometry imaging, we provide here the first direct evidence for phloem localization and translocation of a larger (∼70 nm) fertilizer NP comprised of ZnO encapsulated in mesoporous SiO2 (ZnO@MSN) following foliar deposition. The Si content in the phloem tissue of the petiole connected to the dosed leaf was ∼10 times higher than in the xylem tissue, and ∼100 times higher than the phloem tissue of an untreated tomato plant petiole. Direct evidence of NPs in individual phloem cells has only previously been shown for smaller NPs introduced invasively in the plant. Furthermore, we show that uptake and translocation of the NPs can be enhanced by their application on the abaxial (lower) side of the leaf. Applying ZnO@MSN to the abaxial side of a single leaf resulted in a 56% higher uptake of Zn as well as higher translocation to the younger (upper) leaves and to the roots, than dosing the adaxial (top) side of a leaf. The higher abaxial uptake of NPs is in alignment with the higher stomatal density and lower density of mesophyll tissues on that side and has not been demonstrated before.

Electrostatics Control Nanoparticle Interactions with Model and Native Cell Walls of Plants and Algae

A lack of mechanistic understanding of nanomaterial interactions with plants and algae cell walls limits the advancement of nanotechnology-based tools for sustainable agriculture. We systematically investigated the influence of nanoparticle charge on the interactions with model cell wall surfaces built with cellulose or pectin and performed a comparative analysis with native cell walls of Arabidopsis plants and green algae (Choleochaete). The high affinity of positively charged carbon dots (CDs) (46.0 ± 3.3 mV, 4.3 ± 1.5 nm) to both model and native cell walls was dominated by the strong ionic bonding between the surface amine groups of CDs and the carboxyl groups of pectin. In contrast, these CDs formed weaker hydrogen bonding with the hydroxyl groups of cellulose model surfaces. The CDs of similar size with negative (-46.2 ± 1.1 mV, 6.6 ± 3.8 nm) or neutral (-8.6 ± 1.3 mV, 4.3 ± 1.9 nm) ζ-potentials exhibited negligible interactions with cell walls. Real-time monitoring of CD interactions with model pectin cell walls indicated higher absorption efficiency (3.4 ± 1.3 10-9) and acoustic mass density (313.3 ± 63.3 ng cm-2) for the positively charged CDs than negative and neutral counterparts (p < 0.001 and p < 0.01, respectively). The surface charge density of the positively charged CDs significantly enhanced these electrostatic interactions with cell walls, pointing to approaches to control nanoparticle binding to plant biosurfaces. Ca2+-induced cross-linking of pectin affected the initial absorption efficiency of the positively charged CD on cell wall surfaces (∼3.75 times lower) but not the accumulation of the nanoparticles on cell wall surfaces. This study developed model biosurfaces for elucidating fundamental interactions of nanomaterials with cell walls, a main barrier for nanomaterial translocation in plants and algae in the environment, and for the advancement of nanoenabled agriculture with a reduced environmental impact.

Improving RNA-based crop protection through nanotechnology and insights from cross-kingdom RNA trafficking

Spray-induced gene silencing (SIGS) is a powerful and eco-friendly method for crop protection. Based off the discovery of RNA uptake ability in many fungal pathogens, the application of exogenous RNAs targeting pathogen/pest genes results in gene silencing and infection inhibition. However, SIGS remains hindered by the rapid degradation of RNA in the environment. As extracellular vesicles are used by plants, animals, and microbes in nature to transport RNAs for cross-kingdom/species RNA interference between hosts and microbes/pests, nanovesicles and other nanoparticles have been used to prevent RNA degradation. Efforts examining the effect of nanoparticles on RNA stability and internalization have identified key attributes that can inform better nanocarrier designs for SIGS. Understanding sRNA biogenesis, cross-kingdom/species RNAi, and how plants and pathogens/pests naturally interact are paramount for the design of SIGS strategies. Here, we focus on nanotechnology advancements for the engineering of innovative RNA-based disease control strategies against eukaryotic pathogens and pests.

Flash NanoPrecipitation as an Agrochemical Nanocarrier Formulation Platform: Phloem Uptake and Translocation after Foliar Administration

The increasing severity of pathogenic and environmental stressors that negatively affect plant health has led to interest in developing next-generation agrochemical delivery systems capable of precisely transporting active agents to specific sites within plants. In this work, we adapt Flash NanoPrecipitation (FNP), a scalable nanocarrier (NC) formulation technology used in the pharmaceutical industry, to prepare organic core-shell NCs and study their efficacy as foliar or root delivery vehicles. NCs ranging in diameter from 55 to 200 nm, with surface zeta potentials from -40 to +40 mV, and with seven different shell material properties were prepared and studied. Shell materials included synthetic polymers poly(acrylic acid), poly(ethylene glycol), and poly(2-(dimethylamino)ethyl methacrylate), naturally occurring compounds fish gelatin and soybean lecithin, and semisynthetic hydroxypropyl methylcellulose acetate succinate (HPMCAS). NC cores contained a gadolinium tracer for tracking by mass spectrometry, a fluorescent dye for tracking by confocal microscopy, and model hydrophobic compounds (alpha tocopherol acetate and polystyrene) that could be replaced by agrochemical payloads in subsequent applications. After foliar application onto tomato plants with Silwet L-77 surfactant, internalization efficiencies of up to 85% and NC translocation efficiencies of up to 32% were observed. Significant NC trafficking to the stem and roots suggests a high degree of phloem loading for some of these formulations. Results were corroborated by confocal microscopy and synchrotron X-ray fluorescence mapping. NCs stabilized by cellulosic HPMCAS exhibited the highest degree of translocation, followed by formulations with a significant surface charge. The results from this work indicate that biocompatible materials like HPMCAS are promising agrochemical delivery vehicles in an industrially viable pharmaceutical nanoformulation process (FNP) and shed light on the optimal properties of organic NCs for efficient foliar uptake, translocation, and delivery.

Particle Size Determines the Phytotoxicity of ZnO Nanoparticles in Rice (Oryza sativa L.) Revealed by Spatial Imaging Techniques

To understand the nanotoxicity effects on plants, it is necessary to systematically study the distribution of NPs in vivo. Herein, elemental and particle-imaging techniques were used to unravel the size effects of ZnO NPs on phytotoxicity. Small-sized ZnO NPs (5, 20, and 50 nm) showed an inhibitory effect on the length and biomass of rice (Oryza sativa L.) used as a model plant. ZnO NP nanotoxicity caused rice root cell membrane damage, increased the malondialdehyde content, and activated antioxidant enzymes. As a control, the same dose of Zn2+ salt did not affect the physiological and biochemical indices of rice, suggesting that the toxicity is caused by the entry of the ZnO NPs and not the dissolved Zn2+. Laser ablation inductively coupled plasma optical emission spectroscopy analysis revealed that ZnO NPs accumulated in the rice root vascular tissues of the rhizodermis and procambium. Furthermore, transmission electron microscopy confirmed that the NPs were internalized to the root tissues. These results suggest that ZnO NPs may exist in the rice root system and that their particle size could be a crucial factor in determining toxicity. This study provides evidence of the size-dependent phytotoxicity of ZnO NPs.

Synchrotron science for sustainability: life cycle of metals in the environment

The movement of metals through the environment links together a wide range of scientific fields: from earth sciences and geology as weathering releases minerals; to environmental sciences as metals are mobilized and transformed, cycling through soil and water; to biology as living things take up metals from their surroundings. Studies of these fundamental processes all require quantitative analysis of metal concentrations, locations, and chemical states. Synchrotron X-ray tools can address these requirements with high sensitivity, high spatial resolution, and minimal sample preparation. This perspective describes the state of fundamental scientific questions in the lifecycle of metals, from rocks to ecosystems, from soils to plants, and from environment to animals. Key X-ray capabilities and facility infrastructure for future synchrotron-based analytical resources serving these areas are summarized, and potential opportunities for future experiments are explored.

Oscillatory and Relaxation Study of the Interfacial Rheology of Star Polymers with Low-Grafting-Density PEO Arms and Hydrophobic Poly(divinylbenzene) Cores

Star polymers have been gaining interest due to their tunable properties. They have been used as effective stabilizers for Pickering emulsions. Herein, star polymers were synthesized via activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP). Poly(ethylene oxide) (PEO) with terminal α-bromoisobutyrate ATRP functionality was used as a macroinitiator and divinylbenzene as a crosslinker for the arm-first star synthesis. Stars with PEO arms with a molar mass of either 2 or 5 kDa had a relatively low density of grafted chains, i.e., ca. 0.25 chain/nm². The properties of PEO stars adsorbed at oil-water interfaces were investigated using interfacial tension and interfacial rheology. The magnitude of interfacial tensions at oil-water interfaces depends on the nature of the oil phase, being lower at the m-xylene/water interface than at the n-dodecane/water interface. Small differences were observed for stars with different molecular weights of PEO arms. The overall behavior of PEO stars adsorbed at an interface can be considered as an intermediate between a particle and a linear/branched polymer. Obtained results offer an important insight into the interfacial rheology of PEO star polymers in the context of their application as stabilizers for Pickering emulsions.

Temperature-Responsive Bottlebrush Polymers Deliver a Stress-Regulating Agent In Vivo for Prolonged Plant Heat Stress Mitigation

Anticipated increases in the frequency and intensity of extreme temperatures will damage crops. Methods that efficiently deliver stress-regulating agents to crops can mitigate these effects. Here, we describe high aspect ratio polymer bottlebrushes for temperature-controlled agent delivery in plants. The foliar-applied bottlebrush polymers had near complete uptake into the leaf and resided in both the apoplastic regions of the leaf mesophyll and in cells surrounding the vasculature. Elevated temperature enhanced the in vivo release of spermidine (a stress-regulating agent) from the bottlebrushes, promoting tomato plant (Solanum lycopersicum) photosynthesis under heat and light stress. The bottlebrushes continued to provide protection against heat stress for at least 15 days after foliar application, whereas free spermidine did not. About 30% of the ∼80 nm short and ∼300 nm long bottlebrushes entered the phloem and moved to other plant organs, enabling heat-activated release of plant protection agents in phloem. These results indicate the ability of the polymer bottlebrushes to release encapsulated stress relief agents when triggered by heat to provide long-term protection to plants and the potential to manage plant phloem pathogens. Overall, this temperature-responsive delivery platform provides a new tool for protecting plants against climate-induced damage and yield loss.

What is missing to advance foliar fertilization using nanotechnology?

An urgent challenge within agriculture is to improve fertilizer efficiency in order to reduce the environmental footprint associated with an increased production of crops on existing farmland. Standard soil fertilization strategies are often not very efficient due to immobilization in the soil and losses of nutrients by leaching or volatilization. Foliar fertilization offers an attractive supplementary strategy as it bypasses the adverse soil processes, but implementation is often hampered by a poor penetration through leaf barriers, leaf damage, and a limited ability of nutrients to translocate. Recent advances within bionanotechnology offer a range of emerging possibilities to overcome these challenges. Here we review how nanoparticles can be tailored with smart properties to interact with plant tissue for a more efficient delivery of nutrients.

Polymer nanoparticles pass the plant interface

As agriculture strives to feed an ever-increasing number of people, it must also adapt to increasing exposure to minute plastic particles. To learn about the accumulation of nanoplastics by plants, we prepared well-defined block copolymer nanoparticles by aqueous dispersion polymerisation. A fluorophore was incorporated via hydrazone formation and uptake into roots and protoplasts of Arabidopsis thaliana was investigated using confocal microscopy. Here we show that uptake is inversely proportional to nanoparticle size. Positively charged particles accumulate around root surfaces and are not taken up by roots or protoplasts, whereas negatively charged nanoparticles accumulate slowly and become prominent over time in the xylem of intact roots. Neutral nanoparticles penetrate rapidly into intact cells at the surfaces of plant roots and into protoplasts, but xylem loading is lower than for negative nanoparticles. These behaviours differ from those of animal cells and our results show that despite the protection of rigid cell walls, plants are accessible to nanoplastics in soil and water.

Mesoporous silica size, charge, and hydrophobicity affect the loading and releasing performance of lambda-cyhalothrin

Nanopesticides are attracting increasing attention as a promising technology in agriculture to improve insecticidal efficacy, decrease pesticides uses, and reduce potential environmental impacts. We synthesized mesoporous silica nanoparticles, i.e., Mobil Composition of Matter No.48 (MCM-48), with different sizes (63-130 nm), charges (-22 to 12 mV), and hydrophobicity (water contact angle 29-103°) to assess their loading amount and release of a typical poorly soluble halogenated pyrethroid (i.e., lambda-cyhalothrin particles, LCNS). The smallest MCM-48 displayed relatively higher loading amount of LCNS (~16%) compared to the larger MCM-48 nanoparticles, likely because of its higher pore volume (1.46 cm³ g^-1) and pore size (3.56 nm). LCNS loading amount was further improved to ~26% and ~36% after -NH₂ (positively charged) and -CH₃ (hydrophobic) functionalization, respectively, probably due to hydrogen bonding, electrostatic, and hydrophobic interactions with LCNS. Loading LCNS in MCM-48 nanoparticles also significantly improved its dispersion in water and ultraviolet (UV) light stability, with a 3-7 times longer half-life than that of free LCNS. Although the -NH₂ and -CH₃ modifications of MCM-48 slightly decreased the UV stability of LCNS, they significantly decreased the release efficiency of LCNS, possibly because of their stronger interactions with LCNS. In addition, the insecticidal effects of LCNS-loaded MCM-48 were more efficient and longer than those of free LCNS. The findings clarify the relationships between physicochemical properties and performance of mesoporous silica nanoparticles, and will inform the rational design of materials for controlled release of pesticides and sustainable control of pests.

A Preparation Method of Nano-Pesticide Improves the Selective Toxicity toward Natural Enemies

Various nano-delivery systems have been designed to deliver synthetic/botanical pesticides for improved bioactivity. However, the enhanced toxicity of nanocarrier-loaded pesticides may injure the natural enemies, and their selective toxicity should be evaluated before the large-scale application. In this context, a star polymer (SPc)-based cyantraniliprole (CNAP) nano-delivery system was constructed, and its selective toxicity was evaluated using pest Frankliniella occidentalis (WFT) and predator Orius sauteri. The amide NH of CNAP could assemble with carbonyl groups or tertiary amines of SPc through hydrogen bonds to form CNAP/SPc complex spontaneously. The above self-assembly decreased the particle size of CNAP from 808 to 299 nm. With the help of SPc, the lethal concentration 50 (LC₅₀) values of CNAP decreased from 99 to 54 mg/L and 230 to 173 mg/L toward WFTs and O. sauteri due to the enhancement of broad-spectrum bioactivity. Interestingly, the toxicity selective ratio (TSR) of CNAP increased from 2.33 to 3.23 with the help of SPc, revealing the higher selectivity of SPc-loaded CNAP. To our knowledge, it was the first successful exploration of the selective toxicity of nanocarrier-loaded pesticides, and the higher selective toxicity of SPc-loaded CNAP was beneficial for alleviating the negative impacts on predators.

Interaction of Nanoatrazine and Target Organism: Evaluation of Fate and Photosystem II Inhibition in Hydroponically Grown Mustard (Brassica juncea) Plants

Poly(epsilon-caprolactone) nanoparticles are an efficient carrier system for atrazine. However, there is a gap regarding the effects of nanoencapsulation on herbicide-plant interactions. Here, we evaluate the fate and photosystem II inhibition of nano and commercial atrazine in hydroponically grown mustard (Brassica juncea) plants whose roots were exposed to the formulations. In addition, to quantify the endogenous levels of atrazine in plant organs, we measured the inhibition of photosystem II activity by both formulations. Moreover, the fluorescently labeled nanoatrazine was tracked in plant tissues using confocal microscopy. The nanoencapsulation induced greater inhibition of photosystem II activity as well as higher accumulation of atrazine in roots and leaves. The nanoparticles were quickly absorbed by the roots, being detected in the vascular tissues and the leaves. Overall, these results provide insights into the mechanisms involved in the enhanced preemergent herbicidal activity of nanoatrazine against target plants.

Nitric oxide-releasing nanomaterials: from basic research to potential biotechnological applications in agriculture

Nitric oxide (NO) is a multifunctional gaseous signal that modulates the growth, development and stress tolerance of higher plants. NO donors have been used to boost plant endogenous NO levels and to activate NO-related responses, but this strategy is often hindered by the relative instability of donors. Alternatively, nanoscience offers a new, promising way to enhance NO delivery to plants, as NO-releasing nanomaterials (e.g. S-nitrosothiol-containing chitosan nanoparticles) have many beneficial physicochemical and biochemical properties compared to non-encapsulated NO donors. Nano NO donors are effective in increasing tissue NO levels and enhancing NO effects both in animal and human systems. The authors believe, and would like to emphasize, that new trends and technologies are essential for advancing plant NO research and nanotechnology may represent a breakthrough in traditional agriculture and environmental science. Herein, we aim to draw the attention of the scientific community to the potential of NO-releasing nanomaterials in both basic and applied plant research as alternatives to conventional NO donors, providing a brief overview of the current knowledge and identifying future research directions. We also express our opinion about the challenges for the application of nano NO donors, such as the environmental footprint and stakeholder's acceptance of these materials.

Star Polymers with Designed Reactive Oxygen Species Scavenging and Agent Delivery Functionality Promote Plant Stress Tolerance

Plant abiotic stress induces reactive oxygen species (ROS) accumulation in leaves that can decrease photosynthetic performance and crop yield. Materials that scavenge ROS and simultaneously provide nutrients in vivo are needed to manage this stress. Here, we incorporated both ROS scavenging and ROS triggered agent release functionality into an ∼20 nm ROS responsive star polymer (RSP) poly(acrylic acid)-block-poly((2-(methylsulfinyl)ethyl acrylate)-co-(2-(methylthio)ethyl acrylate)) (PAA-b-P(MSEA-co-MTEA)) that alleviated plant stress by simultaneous ROS scavenging and nutrient agent release. Hyperspectral imaging indicates that all of the RSP penetrates through the tomato leaf epidermis, and 32.7% of the applied RSP associates with chloroplasts in mesophyll. RSP scavenged up to 10 μmol mg^-1 ROS in vitro and suppressed ROS in vivo in stressed tomato (Solanum lycopersicum) leaves. Reaction of the RSP with H₂O₂in vitro enhanced the release of nutrient agent (Mg²⁺) from star polymers. Foliar applied RSP increased photosynthesis in plants under heat and light stress compared to untreated controls, enhancing the carbon assimilation, quantum yield of CO₂ assimilation, Rubisco carboxylation rate, and photosystem II quantum yield. Mg loaded RSP improved photosynthesis in Mg deficient plants, mainly by promoting Rubisco activity. These results indicate the potential of ROS scavenging nanocarriers like RSP to alleviate abiotic stress in crop plants, allowing crop plants to be more resilient to heat stress, and potentially other climate change induced abiotic stressors.

Bioaccumulation and phytotoxicity of ZnO nanoparticles in soil-grown Brassica chinensis L. and potential risks

Zinc oxide nanoparticles (ZnO NPs) widely used have caught the attention of researchers, nevertheless, phytotoxicity, bioaccumulation, and potential risks thereof to the green leafy still have knowledge defects. A pot experiment was intended to cultivate pakchoi (Brassica chinensis L.) following root exposure to ZnO NPs and Zn²⁺. ZnO NPs promoted plant growth and Zn accumulation, formed a dose-dependent effect on chlorophyll and carotenoids, and induced fluctuations in antioxidant enzyme activities and alleviated the oxidative damage of pakchoi. Particularly, 1000 mg kg^-1 ZnO NPs resulted in malondialdehyde (MDA) content of pakchoi shoots that was 87% higher than control. TEM was used to observe ZnO NPs of root cells and found that its possible way to enter the plant was endocytosis. Research on the content of several co-existing nutrients showed that 100 mg kg^-1 ZnO NPs significantly (p < 0.05) promoted the absorption of Ca, P and Fe by pakchoi shoots. In parallel, the hazard quotient (HQ) was used to assess the potential health risk of ZnO NPs.

A pH Dual-Responsive Multifunctional Nanoparticle Based on Mesoporous Silica with Metal-Polymethacrylic Acid Gatekeeper for Improving Plant Protection and Nutrition

Integrating pesticides and mineral elements into a multi-functional stimuli-responsive nanocarrier can have a synergistic effect on protecting plants from pesticides and the supply of nutrients. Herein, a pH dual-responsive multifunctional nanosystem regulated by coordination bonding using bimodal mesoporous silica (BMMs) as a carrier and coordination complexes of ferric ion and polymethacrylic acid (PMAA/Fe3+) as the gatekeeper was constructed to deliver prochloraz (Pro) for the smart treatment of wilt disease (Pro@BMMs-PMAA/Fe3+). The loading capacity of Pro@BMMs-PMAA/Fe3+ nanoparticles (Nps) was 24.0% and the "PMMA/Fe3+" complexes deposited on the BMMs surface could effectively protect Pro against photodegradation. The nanoparticles possessed an excellent pH dual-responsive release behavior and better inhibition efficacy against Rhizoctonia solani. Fluorescence tracking experiments showed that Nps could be taken up and transported in fungi and plants, implying that non-systemic pesticides could be successfully delivered into target organisms. Furthermore, BMMS-PMAA/Fe3+ nanocarriers could effectively promote the growth of crop seedlings and had no obvious toxicological influence on the cell viability and the growth of bacteria. This study provides a novel strategy for enhancing plant protection against diseases and reducing the risk to the environment.

Zein and lignin-based nanoparticles as soybean seed treatment: translocation and impact on seed and plant health

Zein nanoparticles (ZNPs) were synthesized with a cationic surfactant, didodecyldimethylammonium bromide (122.9 ± 0.8 nm, + 59.7 ± 4.4 mV) and a non-ionic surfactant, Tween 80 (118.7 ± 1.7 nm, + 26.4 ± 1.1 mV). Lignin-graft-poly(lactic-co-glycolic) acid nanoparticles (LNPs) were made without surfactants (52.9 ± 0.2 nm, − 54.9 ± 0.5 mV). Both samples were applied as antifungal seed treatments on soybeans, and their impact on germination and plant health was assessed. Treated seeds showed high germination rates (> 90% for all treatment groups), similar to the control group (100%). Root and stem lengths and the dry biomass of treated seeds were not statistically distinguishable from the control. Foliage from seed-treated plants was fed to larvae of Chrysodeixis includens with no differences in mortality between treatments. No translocation of fluorescently tagged particles was observed with fluorescence microscopy following seed treatment and germination. Nano-delivered azoxystrobin provided ~ 100% protection when LNPs were used. Results suggest ZNPs and LNPs are safe and effective delivery systems of active compounds for seed treatments.