Barriers, pathways and processes for uptake, translocation and accumulation of nanomaterials in plants – Critical review

Nanoparticles and plants: A focus on analytical characterization techniques

Nanotechnology has brought about significant progress through the use of goods based on nanomaterials. However, concerns remain about the accumulation of these materials in the environment and their potential toxicity to living organisms. Plants have the ability to take in nanomaterials (NMs), which can cause changes in their physiology and morphology. On the other hand, nanoparticles (NPs) have been used to increase plant development and control pests in agriculture by including them into agrochemicals. The challenges of the interaction, internalization, and accumulation of NMs within plant tissues are enormous, mainly because of the various characteristics of NMs and the absence of reliable analytical tools. As our knowledge of the interactions between NMs and plant cells expands, we are able to create novel NMs that are tailored, targeted, and designed to be safe, thus minimizing the environmental consequences of nanomaterials. This review provides a thorough examination and comparison of the main microscopy techniques, spectroscopic methods, and far-field super-resolution methodologies used to examine nanomaterials within the cell walls of plants.

Effect of silver nanoparticles foliar application on the nutritional properties of potato tubers

The aim of presented study was to test nutritional properties of potato tubers and silver ions accumulation pattern after foliar application of silver nanoparticles (AgNPs) during potato vegetation. Potato plants were sprayed with different concentration of Ag nanoparticles (0.1, 1.0 and 10 mg·dm-3) synthesized with incorporation with sodium dodecyl sulphate (SDS) and sodium citrate as stabilizing agent. The lowest amounts of silver ions were transported to the tubers after spraying with AgNPs synthesized with SDS, rather than with citrate. Nevertheless silver ions accumulation in tubers was negligible. SDS method of synthesis was more favourable in terms of nutritional properties of potato tubers. The highest tested concentration of AgNPs_SDS had a favourable effect on a variety of macro- and micronutrients, ascorbic acid and soluble sugars. In turn, lower concentrations of AgNPs_SDS increased the content of phenolic compounds and free radical scavenging efficiency of tubers. These correlations were also confirmed by Principal Component Analysis.

Nanoparticle LDH enhances RNAi efficiency of dsRNA in piercing-sucking pests by promoting dsRNA stability and transport in plants

Piercing-sucking pests are the most notorious group of pests for global agriculture. RNAi-mediated crop protection by foliar application is a promising approach in field trials. However, the effect of this approach on piercing-sucking pests is far from satisfactory due to the limited uptake and transport of double strand RNA (dsRNA) in plants. Therefore, there is an urgent need for more feasible and biocompatible dsRNA delivery approaches to better control piercing-sucking pests. Here, we report that foliar application of layered double hydroxide (LDH)-loaded dsRNA can effectively disrupt Panonychus citri at multiple developmental stages. MgAl-LDH-dsRNA targeting Chitinase (Chit) gene significantly promoted the RNAi efficiency and then increased the mortality of P. citri nymphs by enhancing dsRNA stability in gut, promoting the adhesion of dsRNA onto leaf surface, facilitating dsRNA internalization into leaf cells, and delivering dsRNA from the stem to the leaf via the vascular system of pomelo plants. Finally, this delivery pathway based on other metal elements such as iron (MgFe-LDH) was also found to significantly improve the protection against P. citri and the nymphs or larvae of Diaphorina citri and Aphis gossypii, two other important piercing-sucking hemipeteran pests, indicating the universality of nanoparticles LDH in promoting the RNAi efficiency and mortality of piercing-sucking pests. Collectively, this study provides insights into the synergistic mechanism for nano-dsRNA systemic translocation in plants, and proposes a potential eco-friendly control strategy for piercing-sucking pests.

Meta-analysis reveals the combined effects of microplastics and heavy metal on plants

The combined pollution of microplastics and heavy metals is becoming increasingly serious, and its effects on toxicology and heavy metal accumulation of plants are closely related to crop yield and population health. Here, we collected 57 studies to investigate the effect of microplastics on heavy metal accumulation in plants and their combined toxicity. An assessment was conducted to discover the primary pollutant responsible for the toxicity of combined pollution on plants. The study examined the influence of microplastic characteristics, heavy metal characteristics, and experimental methods on this pollutant. The results showed that combined toxicity of plants was more similar to heavy metals, whereas microplastics interacted with heavy metals mainly by inducing oxidative stress damage. Culture environment, heavy metal type, experimental duration, microplastic concentration and microplastic size were the main factors affecting heavy metal accumulation in plants. There was a negative correlation between experimental duration, microplastic concentration and microplastic size with heavy metal accumulation in plants. The interactions among influencing factors were found, and microplastic biodegradation was the core factor of the strong interaction. These results provided comprehensive insights and guiding strategies for environmental and public health risks caused by the combined pollution of microplastics and heavy metals.

Zinc oxide nanoparticles application alleviates salinity stress by modulating plant growth, biochemical attributes and nutrient homeostasis in Phaseolus vulgaris L

Salt stress poses a significant challenge to global agriculture, adversely affecting crop yield and food production. The current study investigates the potential of Zinc Oxide (ZnO) nanoparticles (NPs) in mitigating salt stress in common beans. Salt-stressed bean plants were treated with varying concentrations of NPs (25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L) using three different application methods: foliar application, nano priming, and soil application. Results indicated a pronounced impact of salinity stress on bean plants, evidenced by a reduction in fresh weight (24%), relative water content (27%), plant height (33%), chlorophyll content (37%), increased proline (over 100%), sodium accumulation, and antioxidant enzyme activity. Application of ZnO NPs reduced salt stress by promoting physiological growth parameters. The NPs facilitated enhanced plant growth and reduced reactive oxygen species (ROS) generation by regulating plant nutrient homeostasis and chlorophyll fluorescence activity. All the tested application methods effectively mitigate salt stress, with nano-priming emerging as the most effective approach, yielding results comparable to control plants for the tested parameters. This study provides the first evidence that ZnO NPs can effectively mitigate salt stress in bean plants, highlighting their potential to address salinity-induced growth inhibition in crops.

Nanopriming boost seed vigor: Deeper insights into the effect mechanism

Nanopriming, an advanced seed priming technology, is highly praised for its environmental friendliness, safety, and effectiveness in promoting sustainable agriculture. Studies have shown that nanopriming can enhance seed germination by stimulating the expression of aquaporins and increasing amylase production. By applying an appropriate concentration of nanoparticles, seeds can generate reactive oxygen species (ROS), enhance their antioxidant capacity, improve their response to oxidative stress, and enhance their tolerance to both biotic and abiotic stresses. This positive impact extends beyond the seed germination and seedling growth stages, persisting throughout the entire life cycle. This review offers a comprehensive overview of recent research progress in seed priming using various nanoparticles, while also addressing current challenges and future opportunities for sustainable agriculture.

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.

Migration and accumulation of microplastics in soil-plant systems mediated by symbiotic microorganisms and their ecological effects

The coexistence of microorganisms in complex soil environments greatly affects the environmental behavior and ecological effects of microplastics (MPs). However, relevant studies are sparse, and internal mechanisms remain unclear. Herein, arbuscular mycorrhizal fungi (AMF), a common symbiotic microorganism in the soil-plant system, was proved to significantly affect MPs absorption and migration with a "size effect". Specifically, the existence of AMF accelerated small-sized MPs (0.5 μm) uptake but slowed large-sized MPs (2 μm) uptake in lettuce. The content of 0.5 μm MPs absorbed by plants with AMF was 1.26 times that of the non-AMF group, while the content of 2 μm MPs was only 77.62 % that of non-AMF group. Additionally, the different effects of microorganisms on the intake content of MPs with different particle sizes in plants also led to different toxic effects of MPs on lettuce, that is, AMF exacerbated small-size MPs toxicity in lettuce (e.g., reduced plant biomass, photosynthesis, etc), and it weakened large-sized MPs toxicity (e.g., increased plant height, antioxidant enzyme activity, etc). The above phenomenon mainly because of the change in AMF on the plant root structure, which can be visually observed through the intraradical and extraradical hyphae. The symbiotic structure (hyphae) formed by AMF and host plants root could enhance the absorption pathway for small-sized MPs in lettuce, although not for large-sized MPs. Additionally, the effects of AMF varied with the soil environment of differently sized MPs, which promoted the migration of small-particle MPs to plants but aggravated large-particle MPs fixation at the soil interface. These findings could deepen the understanding of MPs pollution in terrestrial systems and provide theoretical basis and technical support to accurately assess soil MPs pollution.

Nanoparticle-plant interactions: Physico-chemical characteristics, application strategies, and transmission electron microscopy-based ultrastructural insights, with a focus on stereological research

Ensuring global food security is pressing among challenges like population growth, climate change, soil degradation, and diminishing resources. Meeting the rising food demand while reducing agriculture's environmental impact requires innovative solutions. Nanotechnology, with its potential to revolutionize agriculture, offers novel approaches to these challenges. However, potential risks and regulatory aspects of nanoparticle (NP) utilization in agriculture must be considered to maximize their benefits for human health and the environment. Understanding NP-plant cell interactions is crucial for assessing risks of NP exposure and developing strategies to control NP uptake by treated plants. Insights into NP uptake mechanisms, distribution patterns, subcellular accumulation, and induced alterations in cellular architecture can be effectively drawn using transmission electron microscopy (TEM). TEM allows direct visualization of NPs within plant tissues/cells and their influence on organelles and subcellular structures at high resolution. Moreover, integrating TEM with stereological principles, which has not been previously utilized in NP-plant cell interaction assessments, provides a novel and quantitative framework to assess these interactions. Design-based stereology enhances TEM capability by enabling precise and unbiased quantification of three-dimensional structures from two-dimensional images. This combined approach offers comprehensive data on NP distribution, accumulation, and effects on cellular morphology, providing deeper insights into NP impact on plant physiology and health. This report highlights the efficient use of TEM, enhanced by stereology, in investigating diverse NP-plant tissue/cell interactions. This methodology facilitates detailed visualization of NPs and offers robust quantitative analysis, advancing our understanding of NP behavior in plant systems and their potential implications for agricultural sustainability.

Negatively Charged Carbon Dots Employed Symplastic and Apoplastic Pathways to Enable Better Plant Delivery than Positively Charged Carbon Dots

Efficient delivery of nanoparticles (NPs) to plants is important for agricultural application. However, to date, we still lack knowledge about how NPs' charge matters for its translocation pathway, i.e., symplastic and apoplastic pathways, in plants. In this study, we synthesized and used negatively charged citrate sourced carbon dots (C-CDs, -37.97 ± 1.89 mV), Cy5 coated C-CDs (Cy5-C-CDs, -41.90 ± 2.55 mV), positively charged PEI coated carbon dots (P-CDs, +43.03 ± 1.71 mV), and Cy5 coated P-CDs (Cy5-P-CDs, +48.80 ± 1.21 mV) to investigate the role of surface charges and coatings on the employed translocation pathways (symplastic and apoplastic pathways) of charged NPs in plants. Our results showed that, different from the higher fluorescence intensity of P-CDs and Cy5-P-CDs in extracellular than intracellular space, the fluorescence intensity of C-CDs and Cy5-C-CDs was similar between intracellular and extracellular space in cucumber and cotton roots. It suggests that the negatively charged CDs were translocated via both symplastic and apoplastic pathways, but the positively charged CDs were mainly translocated via the apoplastic pathway. Furthermore, our results showed that root applied negatively charged C-CDs demonstrated higher leaf fluorescence than did positively charged P-CDs in both cucumber (8.09 ± 0.99 vs 3.75 ± 0.23) and cotton (7.27 ± 1.06 vs 3.23 ± 0.22), indicating that negatively charged CDs have a higher translocation efficiency from root to leaf than do positively charged CDs. It should be noted that CDs do not affect root cell activities, ROS level, and photosynthetic performance in cucumber and cotton, showing its good biocompatibility. Overall, this study not only figured out that root applied negatively charged CDs employed both symplastic and apoplastic pathways to do the transportation in roots compared with mainly the employment of apoplastic pathway for positively charge CDs, but also found that negatively charge CDs could be more efficiently translocated from root to leaf than positively charged CDs, indicating that imparting negative charge to NPs, at least CDs, matters for its efficient delivery in crops.

Nanoparticle-specific transformations dictate nanoparticle effects associated with plants and implications for nanotechnology use in agriculture

Nanotechnology shows potential to promote sustainable and productive agriculture and address the growing population and food demand worldwide. However, the applications of nanotechnology are hindered by the lack of knowledge on nanoparticle (NP) transformations and the interactions between NPs and macromolecules within crops. In this Review, we discuss the beneficial and toxicity-relieving transformation products of NPs that provide agricultural benefits and the toxic and physiology-disturbing transformations that induce phytotoxicities. Based on knowledge related to the management of NP transformations and their long-term effects, we propose feasible design suggestions to attain nano-enabled efficient and sustainable agricultural applications.

Multiomics analysis reveals a substantial decrease in nanoplastics uptake and associated impacts by nano zinc oxide in fragrant rice (Oryza sativa L.)

Nanoplastics (NPs) have emerged as global environmental pollutants with concerning implications for sustainable agriculture. Understanding the underlying mechanisms of NPs toxicity and devising strategies to mitigate their impact is crucial for crop growth and development. Here, we investigated the nanoparticles of zinc oxide (nZnO) to mitigate the adverse effects of 80 nm NPs on fragrant rice. Our results showed that optimized nZnO (25 mg L-1) concentration rescued root length and structural deficits by improving oxidative stress response, antioxidant defense mechanism and balanced nutrient levels, compared to seedlings subjected only to NPs stress (50 mg L-1). Consequently, microscopy observations, Zeta potential and Fourier transform infrared (FTIR) results revealed that NPs were mainly accumulated on the initiation joints of secondary roots and between cortical cells that blocks the nutrients uptake, while the supplementation of nZnO led to the formation of aggregates with NPs, which effectively impedes the uptake of NPs by the roots of fragrant rice. Transcriptomic analysis identified a total of 3973, 3513 and 3380 differentially expressed genes (DEGs) in response to NPs, nZnO and NPs+nZnO, respectively, compared to the control. Moreover, DEGs were significantly enriched in multiple pathways including biosynthesis of secondary metabolite, phenylpropanoid biosynthesis, amino sugar and nucleotide sugar metabolism, carotenoid biosynthesis, plant-pathogen interactions, MAPK signaling pathway, starch and sucrose metabolism, and plant hormone signal transduction. These pathways could play a significant role in alleviating NPs toxicity and restoring fragrant rice roots. Furthermore, metabolomic analysis demonstrated that nZnO application restored 2-acetyl-1-pyrroline (2-AP) pathways genes expression, enzymatic activities, and the content of essential precursors related to 2-AP biosynthesis under NPs toxicity, which ultimately led to the restoration of 2-AP content in the leaves. In conclusion, this study shows that optimized nZnO application effectively alleviates NPs toxic effects and restores both root structure and aroma production in fragrant rice leaves. This research offers a sustainable and practical strategy to enhance crop production under NPs toxicity while emphasizing the pivotal role of essential micronutrient nanomaterials in agriculture.

Interaction of plants and metal nanoparticles: Exploring its molecular mechanisms for sustainable agriculture and crop improvement

Metal nanoparticles offer promising prospects in agriculture, enhancing plant growth and ensuring food security. Silver, gold, copper, and zinc nanoparticles possess unique properties making them attractive for plant applications. Understanding molecular interactions between metal nanoparticles and plants is crucial for unlocking their potential to boost crop productivity and sustainability. This review explores metal nanoparticles in agriculture, emphasizing the need to understand these interactions. By elucidating mechanisms, it highlights the potential for enhancing crop productivity, stress tolerance, and nutrient-use efficiency, contributing to sustainable agriculture and food security. Quantifying benefits and risks reveal significant advantages. Metal nanoparticles enhance crop productivity by 20% on average and reduce disease incidence by up to 50% when used as antimicrobial agents. They also reduce nutrient leaching by 30% and enhance soil carbon sequestration by 15%, but concerns about toxicity, adverse effects on non-target organisms, and nanoparticle accumulation in the food chain must be addressed. Metal nanoparticles influence cellular processes including sensing, signaling, transcription, translation, and post-translational modifications. They act as signaling molecules, activate stress-responsive genes, enhance defense mechanisms, and improve nutrient uptake. The review explores their catalytic role in nutrient management, disease control, precision agriculture, nano-fertilizers, and nano-remediation. A bibliometric analysis offers insights into the current research landscape, highlighting trends, gaps, and future directions. In conclusion, metal nanoparticles hold potential for revolutionizing agriculture, enhancing productivity, mitigating environmental stressors, and promoting sustainability. Addressing risks and gaps is crucial for their safe integration into agricultural practices.

Nanoparticle-mediated defense priming: A review of strategies for enhancing plant resilience against biotic and abiotic stresses

Nanotechnology has emerged as a promising field with the potential to revolutionize agriculture, particularly in enhancing plant defense mechanisms. Nanoparticles (NPs) are instrumental in plant defense priming, where plants are pre-exposed to controlled levels of stress to heighten their alertness and responsiveness to subsequent stressors. This process improves overall plant performance by enabling quicker and more effective responses to secondary stimuli. This review explores the application of NPs as priming agents, utilizing their unique physicochemical properties to bolster plants' innate defense mechanisms. It discusses key findings in NP-based plant defense priming, including various NP types such as metallic, metal oxide, and carbon-based NPs. The review also investigates the intricate mechanisms by which NPs interact with plants, including uptake, translocation, and their effects on plant physiology, morphology, and molecular processes. Additionally, the review examines how NPs can enhance plant responses to a range of stressors, from pathogen attacks and herbivore infestations to environmental stresses. It also discusses NPs' ability to improve plants' tolerance to abiotic stresses like drought, salinity, and heavy metals. Safety and regulatory aspects of NP use in agriculture are thoroughly addressed, emphasizing responsible and ethical deployment for environmental and human health safety. By harnessing the potential of NPs, this approach shows promise in reducing crop losses, increasing yields, and enhancing global food security while minimizing the environmental impact of traditional agricultural practices. The review concludes by emphasizing the importance of ongoing research to optimize NP formulations, dosages, and delivery methods for practical application in diverse agricultural settings.

Isotope Evidence for Rice Accumulation of Newly Deposited and Soil Legacy Cadmium: A Three-Year Field Study

Biogeochemical processes of atmospherically deposited cadmium (Cd) in soils and accumulation in rice were investigated through a three-year fully factorial atmospheric exposure experiment using Cd stable isotopes and diffusive gradients in thin films (DGT). Our results showed that approximately 37-79% of Cd in rice grains was contributed by atmospheric deposition through root and foliar uptake during the rice growing season, while the deposited Cd accounted for a small proportion of the soil pools. The highly bioavailable metals in atmospheric deposition significantly increased the soil DGT-measured bioavailable fraction; yet, this fraction rapidly aged following a first-order exponential decay model, leading to similar percentages of the bioavailable fraction in soils exposed for 1-3 years. The enrichment of light Cd isotopes in the atmospheric deposition resulted in a significant shift toward lighter Cd isotopes in rice plants. Using a modified isotopic mass balance model, foliar and root uptake of deposited Cd accounted for 47-51% and 28-36% in leaves, 41-45% and 22-30% in stems, and 45-49% and 26-30% in grains, respectively. The implications of this study are that new atmospheric deposition disproportionately contributes to the uptake of Cd in rice, and managing emissions thus becomes very important versus remediation of impacted soils.

Fluorescent carbon dot embedded polystyrene: an alternative for micro/nanoplastic translocation study in leguminous plants

Micro/nanoplastics are widespread in terrestrial ecosystem. Even though many studies have been reported on the effects of these in marine environment, studies concerning their accumulation and impact on terrestrial ecosystem have been scanty. The current study was designed to determine how terrestrial plants, especially legumes, interact with micro/nanoplastics to gain insights into their uptake and translocation. The paper describes the synthesis of fluorescent carbon dot embedded polystyrene (CDPS) followed by its characterization. Translocation studies at different concentrations from 2 to 100% (v/v) for tracking the movement and accumulation of microplastics in Vigna radiata and Vigna angularis were performed. The optical properties of the synthesized CDPS were investigated, and their translocation within the plants was visualized using fluorescence microscopy. These findings were further validated by scanning electron microscopy (SEM) imaging of the plant sections. The results showed that concentrations higher than 6% (v/v) displayed noticeable fluorescence in the vascular region and on the cell walls, while concentrations below this threshold did not. The study highlights the potential of utilizing fluorescent CDPS as markers for investigating the ecological consequences and biological absorption of microplastics in agricultural systems. This method offers a unique technique for monitoring and analyzing the routes of microplastic accumulation in edible plants, with significant implications for both food safety and environmental health.

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.

Nano hybrid fertilizers: A review on the state of the art in sustainable agriculture

The advent of Nanohybrid (NH) fertilizers represents a groundbreaking advancement in the pursuit of precision and sustainable agriculture. This review abstract encapsulates the transformative potential of these innovative formulations in addressing key challenges faced by modern farming practices. By incorporating nanotechnology into traditional fertilizer matrices, nanohybrid formulations enable precise control over nutrient release, facilitating optimal nutrient uptake by crops. This enhanced precision not only fosters improved crop yields but also mitigates issues of over-fertilization, aligning with the principles of sustainable agriculture. Furthermore, nanohybrid fertilizers exhibit the promise of minimizing environmental impact. Their controlled release mechanisms significantly reduce nutrient runoff, thereby curbing water pollution and safeguarding ecosystems. This dual benefit of precision nutrient delivery and environmental sustainability positions nanohybrid fertilizers as a crucial tool in the arsenal of precision agriculture practices. The intricate processes of uptake, translocation, and biodistribution of nutrients within plants are examined in the context of nanohybrid fertilizers. The nanoscale features of these formulations play a pivotal role in governing the efficiency of nutrient absorption, internal transport, and distribution within plant tissues. Factors affecting the performance of nanohybrid fertilizers are scrutinized, encompassing aspects such as soil type, crop variety, and environmental conditions. Understanding these variables is crucial for tailoring nanohybrid formulations to specific agricultural contexts, and optimizing their impact on crop productivity and resource efficiency. Environmental considerations are integral to the review, assessing the broader implications of nanohybrid fertilizer application. This review offers a holistic overview of nanohybrid fertilizers in precision and sustainable agriculture. Exploring delivery mechanisms, synthesis methods, uptake dynamics, biodistribution patterns, influencing factors, and environmental implications, it provides a comprehensive understanding of the multifaceted role and implications of nanohybrid fertilizers in advancing modern agricultural practices.

Deciphering the Impact of ZnO Nanoparticles and a Sunscreen Product Containing ZnO on Phosphorus Dynamics and Release in Chlorella pyrenoidosa in Aquatic Systems

Zinc oxide nanoparticles (ZnO NPs) expedite the conversion of organic phosphorus (OP) into PO4-P (Pi), facilitating phosphorus (P) absorption by algae. Our study explored the mechanisms of converting OP (2-aminoethylphosphonic acid (AEP) and β-glycerol phosphate (β-GP)) into Pi in Chlorella pyrenoidosa under P deficiency with sunscreen and ZnO NPs. Cell density followed the order of K2HPO4 > β-GP+ZnO > β-GP > AEP+ZnO > AEP > P-free. ZnO NPs promoted the conversion of β-GP, containing C-O-P bonds (0.028-0.041 mg/L), into Pi more efficiently than AEP, which possesses C-P bonds (0.022-0.037 mg/L). Transcriptomics revealed Pi transport/metabolism (phoB (3.99-12.01 fold), phoR (2.20-5.50 fold), ppa (4.49-10.40 fold), and ppk (2.50-5.40 fold)) and phospholipid metabolism (SQD1 (1.85-2.79 fold), SQD2 (2.60-6.53 fold), MGD (2.13-3.21 fold), and DGD (4.08-7.56 fold)) were up-regulated compared to K2HPO4. 31P nuclear magnetic resonance spectroscopy identified intracellular P as polyphosphate, orthophosphate, and pyrophosphate. Synchrotron radiation-based X-ray near-edge structure spectroscopy indicated that K2HPO4 and Zn3(PO4)2 in β-GP+ZnO were increased by 8.09% and 7.28% compared to AEP+ZnO, suggesting superior P storage in β-GP+ZnO. Overall, ZnO NPs improved photoinduced electron-hole pair separation and charge separation efficiency and amplified the ·OH and ·O2- levels, promoting OP photoconversion into Pi and algae growth.

Heat Waves Coupled with Nanoparticles Induce Yield and Nutritional Losses in Rice by Regulating Stomatal Closure

The frequency, duration, and intensity of heat waves (HWs) within terrestrial ecosystems are increasing, posing potential risks to agricultural production. Cerium dioxide nanoparticles (CeO2 NPs) are garnering increasing attention in the field of agriculture because of their potential to enhance photosynthesis and improve stress tolerance. In the present study, CeO2 NPs decreased the grain yield, grain protein content, and amino acid content by 16.2, 23.9, and 10.4%, respectively, under HW conditions. Individually, neither the CeO2 NPs nor HWs alone negatively affected rice production or triggered stomatal closure. However, under HW conditions, CeO2 NPs decreased the stomatal conductance and net photosynthetic rate by 67.6 and 33.5%, respectively. Moreover, stomatal closure in the presence of HWs and CeO2 NPs triggered reactive oxygen species (ROS) accumulation (increased by 32.3-57.1%), resulting in chloroplast distortion and reduced photosystem II activity (decreased by 9.4-36.4%). Metabolic, transcriptomic, and quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed that, under HW conditions, CeO2 NPs activated a stomatal closure pathway mediated by abscisic acid (ABA) and ROS by regulating gene expression (PP2C, NCED4, HPCA1, and RBOHD were upregulated, while CYP707A and ALMT9 were downregulated) and metabolite levels (the content of γ-aminobutyric acid (GABA) increased while that of gallic acid decreased). These findings elucidate the mechanism underlying the yield and nutritional losses induced by stomatal closure in the presence of CeO2 NPs and HWs and thus highlight the potential threat posed by CeO2 NPs to rice production during HWs.

Emerging concern of nano-pollution in agro-ecosystem: Flip side of nanotechnology

Nanomaterials (NMs) have proven to be a game-changer in agriculture, showcasing their potential to boost plant growth and safeguarding crops. The agricultural sector has widely adopted NMs, benefiting from their small size, high surface area, and optical properties to augment crop productivity and provide protection against various stressors. This is attributed to their unique characteristics, contributing to their widespread use in agriculture. Human exposure from various components of agro-environmental sectors (soil, crops) NMs residues are likely to upsurge with exposure paths may stimulates bioaccumulation in food chain. With the aim to achieve sustainability, nanotechnology (NTs) do exhibit its potentials in various domains of agriculture also have its flip side too. In this review article we have opted a fusion approach using bibliometric based analysis of global research trend followed by a holistic assessment of pros and cons i.e. toxicological aspect too. Moreover, we have also tried to analyse the current scenario of policy associated with the application of NMs in agro-environment.

Combat phytopathogenic bacteria employing Argirium-SUNCs: limits and perspectives

Bacterial plant diseases are difficult to control as the durability of deployed control measures is thwarted by continuous and rapid changing of bacterial populations. Although application of copper compounds to plants is the most widespread and inexpensive control measure, it is often partially efficacious for the frequent appearance of copper-resistant bacterial strains and it is raising concerns for the harmful effects of copper on environment and human health. Consequently, European Community included copper compounds in the list of substances candidates for substitution. Nanotechnologies and the application of nanoparticles seem to respond to the need to find new very effective and durable measures. We believe that Argirium-SUNCs®, silver ultra nanoclusters with an average size of 1.79 nm and characterized by rare oxidative states (Ag2+/3+), represent a valid candidate as a nano-bactericide in the control of plant bacterial diseases. Respect to the many silver nanoparticles described in the literature, Argirium-SUNCs have many strengths due to the reproducibility of the synthesis method, the purity and the stability of the preparation, the very strong (less than 1 ppm) antimicrobial, and anti-biofilm activities. In this mini-review, we provide information on this nanomaterial and on the possible application in agriculture. KEY POINTS: • Argirium-SUNCs have strong antimicrobial activities against phytopathogenic bacteria. • Argirium-SUNCs are a possible plant protection product. • Argirium-SUNCs protect tomato plants against bacterial speck disease.

Exploring Sustainable Agriculture with Nitrogen-Fixing Cyanobacteria and Nanotechnology

The symbiotic relationship between nitrogen-fixing cyanobacteria and plants offers a promising avenue for sustainable agricultural practices and environmental remediation. This review paper explores the molecular interactions between nitrogen-fixing cyanobacteria and nanoparticles, shedding light on their potential synergies in agricultural nanotechnology. Delving into the evolutionary history and specialized adaptations of cyanobacteria, this paper highlights their pivotal role in fixing atmospheric nitrogen, which is crucial for ecosystem productivity. The review discusses the unique characteristics of metal nanoparticles and their emerging applications in agriculture, including improved nutrient delivery, stress tolerance, and disease resistance. It delves into the complex mechanisms of nanoparticle entry into plant cells, intracellular transport, and localization, uncovering the impact on root-shoot translocation and systemic distribution. Furthermore, the paper elucidates cellular responses to nanoparticle exposure, emphasizing oxidative stress, signaling pathways, and enhanced nutrient uptake. The potential of metal nanoparticles as carriers of essential nutrients and their implications for nutrient-use efficiency and crop yield are also explored. Insights into the modulation of plant stress responses, disease resistance, and phytoremediation strategies demonstrate the multifaceted benefits of nanoparticles in agriculture. Current trends, prospects, and challenges in agricultural nanotechnology are discussed, underscoring the need for responsible and safe nanoparticle utilization. By harnessing the power of nitrogen-fixing cyanobacteria and leveraging the unique attributes of nanoparticles, this review paves the way for innovative, sustainable, and efficient agricultural practices.

Strategies for Enhancing Plant Immunity and Resilience Using Nanomaterials for Sustainable Agriculture

Research on plant-nanomaterial interactions has greatly advanced over the past decade. One particularly fascinating discovery encompasses the immunomodulatory effects in plants. Due to the low doses needed and the comparatively low toxicity of many nanomaterials, nanoenabled immunomodulation is environmentally and economically promising for agriculture. It may reduce environmental costs associated with excessive use of chemical pesticides and fertilizers, which can lead to soil and water pollution. Furthermore, nanoenabled strategies can enhance plant resilience against various biotic and abiotic stresses, contributing to the sustainability of agricultural ecosystems and the reduction of crop losses due to environmental factors. While nanoparticle immunomodulatory effects are relatively well-known in animals, they are still to be understood in plants. Here, we provide our perspective on the general components of the plant's immune system, including the signaling pathways, networks, and molecules of relevance for plant nanomodulation. We discuss the recent scientific progress in nanoenabled immunomodulation and nanopriming and lay out key avenues to use plant immunomodulation for agriculture. Reactive oxygen species (ROS), the mitogen-activated protein kinase (MAPK) cascade, and the calcium-dependent protein kinase (CDPK or CPK) pathway are of particular interest due to their interconnected function and significance in the response to biotic and abiotic stress. Additionally, we underscore that understanding the plant hormone salicylic acid is vital for nanoenabled applications to induce systemic acquired resistance. It is suggested that a multidisciplinary approach, incorporating environmental impact assessments and focusing on scalability, can expedite the realization of enhanced crop yields through nanotechnology while fostering a healthier environment.

Co-exposure to tire wear particles and nickel inhibits mung bean yield by reducing nutrient uptake

Soil and terrestrial contamination with microplastics and nanoplastics has been discussed extensively, while tire wear particles (TWPs) have been largely overlooked. We investigated the root-surface interactions and growth response of mung bean (Vigna radiata L.) plants exposed to tire wear particles (TWPs) (0.05, 0.1, and 0.25% w/w) and nickel sulfate (50 and 100 mg kg-1 NiSO4) alone and in co-exposure scenarios for the full life cycle (105 days) under soil conditions. The results show that TWPs adhered to the root surface and reduced the water and nutrient uptake by the plant, particularly at higher concentrations of TWPs (0.25% w/w), without any observed organic contaminant accumulation in the root tissue. TWPs alone at 0.01, 0.1, and 0.25% (w/w) decreased mung bean yield by 11, 28, and 52%, respectively. Co-exposure to TWPs at 0.01, 0.1 and 0.25% w/w with 100 mg kg-1 NiSO4 decreased yield by 73, 79 and 88%, respectively. However, co-exposure to TWPs at 0.01 and 0.1% w/w with 50 mg kg-1 NiSO4 enhanced the yield by 32% and 7%, respectively. These changes in yield and nutritional aspects appear to be linked to Ni's regulatory influence on mineral homeostasis. Moreover, exposure to NiSO4 at 100 mg kg-1 increased Ni uptake in the root, shoot, and grain by 9, 26, and 20-fold, respectively as compared to the unamended control; this corresponded to increased antioxidant enzyme activity (10-127%) as compared to the control. TWPs caused blockages, significantly reducing plant yield and altering nutrient dynamics, highlighting emerging risks to plant health.

Nanowonders in agriculture: Unveiling the potential of nanoparticles to boost crop resilience to salinity stress

Soil salinization significantly affects crop production by reducing crop quality and decreasing yields. Climate change can intensify salinity-related challenges, making the task of achieving global food security more complex. To address the problem of elevated salinity stress in crops, nanoparticles (NPs) have emerged as a promising solution. NPs, characterized by their small size and extensive surface area, exhibit remarkable functionality and reactivity. Various types of NPs, including metal and metal oxide NPs, carbon-based NPs, polymer-based NPs, and modified NPs, have displayed potential for mitigating salinity stress in plants. However, the effectiveness of NPs application in alleviating plant stress is dependent upon multiple factors, such as NPs size, exposure duration, plant species, particle composition, and prevailing environmental conditions. Moreover, alterations to NPs surfaces through functionalization and coating also play a role in influencing plant tolerance to salinity stress. NPs can influence cellular processes by impacting signal transduction and gene expression. They counteract reactive oxygen species (ROS), regulate the water balance, enhance photosynthesis and nutrient uptake and promote plant growth and yield. The objective of this review is to discuss the positive impacts of diverse NPs on alleviating salinity stress within plants. The intricate mechanisms through which NPs accomplish this mitigation are also discussed. Furthermore, this review addresses existing research gaps, recent breakthroughs, and prospective avenues for utilizing NPs to combat salinity stress.

Advancing Simultaneous Extraction and Sequential Single-Particle ICP-MS Analysis for Metallic Nanoparticle Mixtures in Plant Tissues

Engineered nanoparticles (ENPs) have been increasingly used in agricultural operations, leading to an urgent need for robust methods to analyze co-occurring ENPs in plant tissues. In response, this study advanced the simultaneous extraction of coexisting silver, cerium oxide, and copper oxide ENPs in lettuce shoots and roots using macerozyme R-10 and analyzed them by single-particle inductively coupled plasma-mass spectrometry (ICP-MS). Additionally, the standard stock suspensions of the ENPs were stabilized with citrate, and the long-term stability (up to 5 months) was examined for the first time. The method performance results displayed satisfactory accuracies and precisions and achieved low particle concentration and particle size detection limits. Significantly, the oven drying process was proved not to impact the properties of the ENPs; therefore, oven-dried lettuce tissues were used in this study, which markedly expanded the applicability of this method. This robust methodology provides a timely approach to characterize and quantify multiple coexisting ENPs in plants.

Unraveling the impact of nanopollution on plant metabolism and ecosystem dynamics

Nanopollution (NPOs), a burgeoning consequence of the widespread use of nanoparticles (NPs) across diverse industrial and consumer domains, has emerged as a critical environmental issue. While extensive research has scrutinized the repercussions of NPs pollution on ecosystems and human health, scant attention has been directed towards unraveling its implications for plant life. This comprehensive review aims to bridge this gap by delving into the nuanced interplay between NPOs and plant metabolism, encompassing both primary and secondary processes. Our exploration encompasses an in-depth analysis of the intricate mechanisms governing the interaction between plants and NPs. This involves a thorough examination of how physicochemical properties such as size, shape, and surface characteristics influence the uptake and translocation of NPs within plant tissues. The impact of NPOs on primary metabolic processes, including photosynthesis, respiration, nutrient uptake, and water transport. Additionally, this study explored the multifaceted alterations in secondary metabolism, shedding light on the synthesis and modulation of secondary metabolites in response to NPs exposure. In assessing the consequences of NPOs for plant life, we scrutinize the potential implications for plant growth, development, and environmental interactions. The intricate relationships revealed in this review underscore the need for a holistic understanding of the plant-NPs dynamics. As NPs become increasingly prevalent in ecosystems, this investigation establishes a fundamental guide that underscores the importance of additional research to shape sustainable environmental management strategies and address the extensive effects of NPs on the development of plant life and environmental interactions.

Toxicological effects of nanoparticles in plants: Mechanisms involved at morphological, physiological, biochemical and molecular levels

The rapid advancement of nanotechnology has led to unprecedented innovations across diverse industries, including pharmaceuticals, agriculture, cosmetics, electronics, textiles, and food, owing to the unique properties of nanoparticles. The extensive production and unregulated release of synthetic nanoparticles may contribute to nanopollution within the ecosystem. In the agricultural sector, nanotechnology is increasingly utilized to improve plant productivity, enhance resistance to stressors, and reduce the usage of chemicals. However, the uncontrolled discharge of nanoparticles into the natural environment raises concerns regarding possible plant toxicological impacts. The review focuses on the translocation of these particles within the plants, emphasizing their phytotoxicological effects at morphological, physiological, biochemical, and molecular levels. Eventhough the beneficial aspects of these nanoparticles are evident, excessive usage of nanoparticles at higher concentrations may lead to potential adverse effects. The phytotoxicity resulting from excessive amounts of nanoparticles affects seed germination and biomass production, disrupts the photosynthesis system, induces oxidative stress, impacts cell membrane integrity, alters gene expression, causes DNA damage, and leads to epigenetic variations in plants. Nanoparticles are found to directly associate with the cell membrane and cell organelles, leading to the dissolution and release of toxic ions, generation of reactive oxygen species (ROS) and subsequent oxidative stress. The present study signifies and accumulates knowledge regarding the application of nanoparticles in agriculture and illustrates a clear picture of their possible impacts on plants and soil microbes, thereby paving the way for future developments in nano-agrotechnology. The review concludes by addressing current challenges and proposing future directions to comprehend and mitigate the possible biological risks associated with nanoparticles in agriculture.

Plant-nano interactions: A new insight of nano-phytotoxicity

Whether nanoparticles (NPs) are boon or bane for society has been a centre of in-depth debate and key consideration in recent times. Exclusive physicochemical properties like small size, large surface area-to-volume ratio, robust catalytic activity, immense surface energy, magnetism and superior biocompatibility make NPs obligatory in many scientific, biomedical and industrial ventures. Nano-enabled products are newer entrants in the present era. To attenuate environmental stress and maximize crop yields, scientists are tempted to introduce NPs as augmented supplements in agriculture. The feasible approaches for NPs delivery are irrigation, foliar spraying or seed priming. Internalization of excessive NPs to plants endorses negative implications at higher trophic levels via biomagnification. The characteristics of NPs (dimensions, type, solubility, surface charge), applied concentration and duration of exposure are prime factors conferring nanotoxicity in plants. Several reports approved NPs persuaded toxicity can precisely mimic abiotic stress effects. The signature effects of nanotoxicity include poor root outgrowth, biomass reduction, oxidative stress evolution, lipid peroxidation, biomolecular damage, perturbed antioxidants, genotoxicity and nutrient imbalance in plants. NPs stress impels mitogen-activated protein kinase signaling cascade and urges stress responsive defence gene expression to counteract stress in plants. Exogenous supplementation of nitric oxide (NO), arbuscular mycorrhizal fungus (AMF), phytohormones, and melatonin (ME) is novel strategy to circumvent nanotoxicity. Briefly, this review appraises plants' physio-biochemical responses and adaptation scenarios to endure NPs stress. As NPs stress represents large-scale contaminants, advanced research is indispensable to avert indiscriminate NPs usage for synchronizing nano-security in multinational markets.

Zinc oxide nanoparticles influence on plant tolerance to salinity stress: insights into physiological, biochemical, and molecular responses

A slight variation in ecological milieu of plants, like drought, heavy metal toxicity, abrupt changes in temperature, flood, and salt stress disturbs the usual homeostasis or metabolism in plants. Among these stresses, salinity stress is particularly detrimental to the plants, leading to toxic effects and reduce crop productivity. In a saline environment, the accumulation of sodium and chloride ions up to toxic levels significantly correlates with intracellular osmotic pressure, and can result in morphological, physiological, and molecular alterations in plants. Increased soil salinity triggers salt stress signals that activate various cellular-subcellular mechanisms in plants to enable their survival in saline conditions. Plants can adapt saline conditions by maintaining ion homeostasis, activating osmotic stress pathways, modulating phytohormone signaling, regulating cytoskeleton dynamics, and maintaining cell wall integrity. To address ionic toxicity, researchers from diverse disciplines have explored novel approaches to support plant growth and enhance their resilience. One such approach is the application of nanoparticles as a foliar spray or seed priming agents positively improve the crop quality and yield by activating germination enzymes, maintaining reactive oxygen species homeostasis, promoting synthesis of compatible solutes, stimulating antioxidant defense mechanisms, and facilitating the formation of aquaporins in seeds and root cells for efficient water absorption under various abiotic stresses. Thus, the assessment mainly targets to provide an outline of the impact of salinity stress on plant metabolism and the resistance strategies employed by plants. Additionally, the review also summarized recent research efforts exploring the innovative applications of zinc oxide nanoparticles for reducing salt stress at biochemical, physiological, and molecular levels.

Comprehensive framework for overcoming scientific challenges related to assessing radioactive ultra-fine (nano/micro) particles transfer at the atmosphere-leaf interface

Food products are prone into contamination after a nuclear emission of radionuclides. While the mechanisms of emission and deposition of ultrafine radioactive particles are well documented, the transfer of these species from the atmosphere into plants is poorly assessed. This is evident in the lack of quantification of particles distributed within plants, especially regarding particles physical-chemical criteria to plant of different properties. Such knowledge gaps raise the concern about the representativeness of risk assessment tools designed for the transfer evaluation of ionic/soluble species to be qualified for simulating insoluble species exposure and proposes a possible underestimation. This highlights the possible need for special particle codes development to be implemented in models for future emissions. In addition, the later tools utilize transfer factors aggregating relevant sub-processes, suggesting another weak point in their overall reliability. As researchers specialized in the nuclear safety and protection, we intend in this perspective, to develop a compressive analysis of the interaction of ultrafine particles with plants of different specificities at different level processes starting from particles retention and gradual translocation to sink organs. This analysis is leveraged in providing insights for possible improvements in the current modeling tools for better real-life scenarios representation.

Enhancing plant biotechnology by nanoparticle delivery of nucleic acids

Plant biotechnology plays a crucial role in developing modern agriculture and plant science research. However, the delivery of exogenous genetic material into plants has been a long-standing obstacle. Nanoparticle-based delivery systems are being established to address this limitation and are proving to be a feasible, versatile, and efficient approach to facilitate the internalization of functional RNA and DNA by plants. The nanoparticle-based delivery systems can also be designed for subcellular delivery and controlled release of the biomolecular cargo. In this review, we provide a concise overview of the recent advances in nanocarriers for the delivery of biomolecules into plants, with a specific focus on applications to enhance RNA interference, foreign gene transfer, and genome editing in plants.

Graphene Quantum Dots (GQD)-Mediated dsRNA Delivery for the Control of Fusarium Head Blight Disease in Wheat

Graphene quantum dots (GQDs), a class of fluorescent carbon materials, have displayed significant potential in various fields such as energy devices, catalysis, sensing, bioimaging, and drug delivery. Because of their extremely small size, generally less than 100 nm, they also have tremendous potential in plant science research, especially for the delivery of nucleic acids, breaking the barrier of cell walls. In this study, we synthesized GQDs with a size range of 2-5 nm, characterized them, and surface-functionalized them with branched polyethylenimine (bPEI). We then used the surface-functionalized GQDs as carriers to deliver double-stranded RNA (dsRNA) that target two growth-and-development-related genes in Fusarium graminearum─the causative organism of the Fusarium head blight disease of wheat. The successful binding of dsRNA to GQDs-bPEIs was demonstrated through gel-shifting assays, showcasing the potential for efficient dsRNA delivery. We designed dsRNAs targeting the MGV1 and RAS1 genes of F. graminearum by using the pssRNAit pipeline, ensuring high specificity and no off-target effects. The coding sequences of the designed dsRAS1 and dsMGV1 were cloned into the L4440 vector and transformed into the Escherichia coli HT115 strain for dsRNA production. Fungal culture analysis revealed that the inclusion of dsRNAs in potato dextrose agar (PDA) media effectively slowed down the growth. Exogenous spraying experiments both in plate cultures and in intact wheat spikes demonstrated that the dsRNA:GQDs-bPEIs treatment was more effective in restricting fungal mycelium growth or the number of infected spikelets compared to naked dsRNA treatment. Our study demonstrates the promising potential of graphene quantum dots as carriers for dsRNA-based fungal disease management in wheat and other crops.

Uptake and effect of carboxyl-modified polystyrene microplastics on cotton plants

Microplastics (MPs) have emerged as a significant global environmental concern, particularly within agricultural soil systems. The extensive use of plastic film mulching in cotton cultivation has led to the alarming presence of MP pollution in cotton fields. However, the uptake and effects of MPs on the growth of cotton plants are poorly understood. In this study, we conducted a comprehensive analysis of hydroponically cultured cotton seedlings at the phenotypic, transcriptional, and metabolic levels after exposure to carboxyl-modified polystyrene microplastics (PS-COOH). Treatment with three concentrations of PS-COOH (100, 300, and 500 mg/L) resulted in notable growth inhibition of treated plants and exhibited a dose-dependent effect. And, PS-COOH can invade cotton roots and be absorbed through the intercellular spaces via apoplastic uptake, with accumulation commensurate with treatment duration. Transcriptomic analysis showed significant up-regulation of genes associated with antioxidant activity in response to 300 mg/L PS-COOH treatment, suggesting the induction of oxidative stress. In addition, the PS-COOH treatment activated the phenylpropanoid biosynthesis pathway, leading to lignin and flavonoid accumulation, and altered sucrose catabolism. These findings illustrate the absorption and effects of MPs on cotton seedlings and offer valuable insights into the potential toxicity of MPs to plants in soil mulched with plastic film.

The distribution, fate, and environmental impacts of food additive nanomaterials in soil and aquatic ecosystems

Nanomaterials in the food industry are used as food additives, and the main function of these food additives is to improve food qualities including texture, flavor, color, consistency, preservation, and nutrient bioavailability. This review aims to provide an overview of the distribution, fate, and environmental and health impacts of food additive nanomaterials in soil and aquatic ecosystems. Some of the major nanomaterials in food additives include titanium dioxide, silver, gold, silicon dioxide, iron oxide, and zinc oxide. Ingestion of food products containing food additive nanomaterials via dietary intake is considered to be one of the major pathways of human exposure to nanomaterials. Food additive nanomaterials reach the terrestrial and aquatic environments directly through the disposal of food wastes in landfills and the application of food waste-derived soil amendments. A significant amount of ingested food additive nanomaterials (> 90 %) is excreted, and these nanomaterials are not efficiently removed in the wastewater system, thereby reaching the environment indirectly through the disposal of recycled water and sewage sludge in agricultural land. Food additive nanomaterials undergo various transformation and reaction processes, such as adsorption, aggregation-sedimentation, desorption, degradation, dissolution, and bio-mediated reactions in the environment. These processes significantly impact the transport and bioavailability of nanomaterials as well as their behaviour and fate in the environment. These nanomaterials are toxic to soil and aquatic organisms, and reach the food chain through plant uptake and animal transfer. The environmental and health risks of food additive nanomaterials can be overcome by eliminating their emission through recycled water and sewage sludge.

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.

Metabolomics reveals the phytotoxicity mechanisms of foliar spinach exposed to bulk and nano sizes of PbCO3

PbCO3 is an ancient raw material for Pb minerals and continues to pose potential risks to the environment and human health through mining and industrial processes. However, the specific effects of unintentional PbCO3 discharge on edible plants remain poorly understood. This study unravels how foliar application of PbCO3 induces phytotoxicity by potentially influencing leaf morphology, photosynthetic pigments, oxidative stress, and metabolic pathways related to energy regulation, cell damage, and antioxidant defense in Spinacia oleracea L. Additionally, it quantifies the resultant human health risks. Plants were foliarly exposed to PbCO3 nanoparticles (NPs) and bulk products (BPs), as well as Pb2+ at 0, 5, 10, 25, 50, and 100 mg·L-1 concentrations once a day for three weeks. The presence and localization of PbCO3 NPs inside the plant cells were confirmed by TEM-EDS analysis. The maximum accumulation of total Pb was recorded in the root (2947.77 mg·kg-1 DW for ion exposure), followed by the shoot (942.50 mg·kg-1 DW for NPs exposure). The results revealed that PbCO3 and Pb2+ exposure had size- and dose-dependent inhibitory effects on spinach length, biomass, and photosynthesis attributes, inducing impacts on the antioxidase activity of CAT, membrane permeability, and nutrient elements absorption and translocation. Pb2+ exhibited pronounced toxicity in morphology and chlorophyll; PbCO3 BP exposure accumulated the most lipid peroxidation products of MDA and H2O2; and PbCO3 NPs triggered the largest cell membrane damage. Furthermore, PbCO3 NPs at 10 and 100 mg·L-1 induced dose-dependent metabolic reprogramming in spinach leaves, disturbing the metabolic mechanisms related to amino acids, antioxidant defense, oxidative phosphorylation, fatty acid cycle, and the respiratory chain. The spinach showed a non-carcinogenic health risk hierarchy: Pb2+ > PbCO3 NPs > PbCO3 BPs, with children more vulnerable than adults. These findings enhance our understanding of PbCO3 particle effects on food security, emphasizing the need for further research to minimize their impact on human dietary health.

Mesoporous Silica Nanoparticles Mediate SiRNA Delivery for Long-Term Multi-Gene Silencing in Intact Plants

RNA interference (RNAi) is a powerful tool for understanding and manipulating signaling pathways in plant science, potentially facilitating the accelerated development of novel plant traits and crop yield improvement. The common strategy for delivering siRNA into intact plants using agrobacterium or viruses is complicated and time-consuming, limiting the application of RNAi in plant research. Here, a novel delivery method based on mesoporous silica nanoparticles (MSNs) is reported, which allows for the efficient delivery of siRNA into mature plant leaves via topical application without the aid of mechanical forces, achieving transient gene knockdown with up to 98% silencing efficiency at the molecular level. In addition, this method is nontoxic to plant leaves, enabling the repeated delivery of siRNA for long-term silencing. White spots and yellowing phenotypes are observed after spraying the MSN-siRNA complex targeted at phytoene desaturase and magnesium chelatase genes. After high light treatment, photobleaching phenotypes are also observed by spraying MSNs-siRNA targeted at genes into the Photosystem II repair cycle. Furthermore, the study demonstrated that MSNs can simultaneously silence multiple genes. The results suggest that MSN-mediated siRNA delivery is an effective tool for long-term multi-gene silencing, with great potential for application in plant functional genomic analyses and crop improvement.

The cellular consequences of particulate matter pollutants in plants: Safeguarding the harmonious integration of structure and function

Particulate matter (PM) pollution is one of the pressing environmental concerns confronting human civilization in the face of the Anthropocene era. Plants are continuously exposed to an accelerating PM, threatening their growth and productivity. Although plants and plant-based infrastructures can potentially reduce ambient air pollutants, PM still affects them morphologically, anatomically, and physiologically. This review comprehensively summarizes an up-to-date review of plant-PM interaction among different functional plant groups, PM deposition and penetration through aboveground and belowground plant parts, and plants' cellular strategies. Upon exposure, PM represses lipid desaturases, eventually leading to modification of cell wall and membrane and altering cell fluidity; consequently, plants can sense the pollutants and, thus, adapt different cellular strategies. The PM also causes a reduction in the photosynthetically active radiation. The study demonstrated that plants reduce stomatal density to avoid PM uptake and increase stomatal index to compensate for decreased gaseous exchange efficiency and transpiration rates. Furthermore, genes and gene sets associated with photosynthesis, glycolysis, gluconeogenesis, and the TCA cycle were dramatically lowered by PM stress. Several transcription factors, including MYB, C2H2, C3H, G2-like, and WRKY were induced, and metabolites such as proline and soluble sugar were accumulated to increase resistance against stressors. In addition, enzymatic and non-enzymatic antioxidants were also accumulated to scavenge the PM-induced reactive oxygen species (ROS). Taken together, this review provides an insight into plants' underlying cellular mechanisms and gene regulatory networks in response to the PM to determine strategies to preserve their structural and functional blend in the face of particulate pollution. The study concludes by recommending that future research should precisely focus on plants' response to short- and long-term PM exposure.

Recent advances in nano-fertilizers: synthesis, crop yield impact, and economic analysis

The escalating global demand for food production has predominantly relied on the extensive application of conventional fertilizers (CFs). However, the increased use of CFs has raised concerns regarding environmental risks, including soil and water contamination, especially within cereal-based cropping systems. In response, the agricultural sector has witnessed the emergence of healthier alternatives by utilizing nanotechnology and nano-fertilizers (NFs). These innovative NFs harness the remarkable properties of nanoparticles, ranging in size from 1 to 100 nm, such as nanoclays and zeolites, to enhance nutrient utilization efficiency. Unlike their conventional counterparts, NFs offer many advantages, including variable solubility, consistent and effective performance, controlled release mechanisms, enhanced targeted activity, reduced eco-toxicity, and straightforward and safe delivery and disposal methods. By facilitating rapid and complete plant absorption, NFs effectively conserve nutrients that would otherwise go to waste, mitigating potential environmental harm. Moreover, their superior formulations enable more efficient promotion of sustainable crop growth and production than conventional fertilizers. This review comprehensively examines the global utilization of NFs, emphasizing their immense potential in maintaining environmentally friendly crop output while ensuring agricultural sustainability.

Evidence for the transportation of aggregated microplastics in the symplast pathway of oilseed rape roots and their impact on plant growth

As an emerging contaminant, microplastics are absorbed by crops, causing diverse impacts on plants. Plants may have different physiological responses to different uptake modes of microplastics various stage of growth. In this study, the distribution of polystyrene (PS) microspheres in the roots of oilseed rape and the physiological responses at different growth stages were investigated by confocal laser scanning microscope, scanning electron microscopy, and biochemical analysis. This study, conducted via scanning electron microscopy, discovered that agglomerates of microspheres, rather than individual plastic pellets, were taken up by plant roots in solution for the first time. The agglomerates subsequently migrate into the vascular bundles of the root system. Moreover, this study provided the proof for the first time that PS is transported in plants via the symplast system. On the physiological and biochemical function, the exposure of PS at the flowering and bolting stages caused oxidative stress on oilseed rape. That is, the addition of PS with different particle sizes significantly increased peroxidase (POD), malondialdehyde (MDA), photosynthetic rate, chlorophyll content and inhibited superoxide dismutase (SOD) content in oilseed rape at different developmental stages. These changes regulated the chloroplast structure and chlorophyll synthesis, maintained a high photosynthetic rate, and mitigated the toxicity of PS. In addition, correlation analysis showed that MDA and citric acid contents were significantly positively correlated with chlorophyll contents (p < 0.05), which suggested that the 80 nm PS treatment stimulated organic acid secretion in oilseed rape at the bolting stage to maintain a higher chlorophyll content. This study expands the current understanding of the effects of microplastics on crop growth, and the results holding significant implications for exploring the impact of microplastics on vegetables during various developmental stages and for future risk assessment.

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.

Studies on the transfer effect of aged polyethylene microplastics in soil-plant system

The widespread use of polyethylene (PE) agricultural films has led to a large accumulation of microplastics in soil, and the environmental effects of microplastics on soil-plants have received increasing attention. In the actual soil environment, microplastics undergo significant changes in their physicochemical properties due to aging, accompanied by complex ecological and environmental effects. However, the quantitative understanding of the environmental effects of microplastic aging in soil-plant systems is still unclear. Therefore, this study investigated the effects of aged and unaged PE microplastics on ecological functions and microplastic transfer mechanisms in soil-plant system, and confirmed the transport behavior of micrometer-sized microplastics (26 μm) within maize plants, expanding the upper size limit of existing studies on microplastic transport within plants. The accumulation of microplastics in maize was also quantitatively assessed in combination with the self-established method of Eu marked PE. The mobility ratio of microplastics from soil to roots, roots to stems, and stems to leaves was 1.07%, 0.76%, and 103.28%, respectively. This study provides a scientific understanding for the environmental effects of microplastics in soil-plants systems quantitatively.

Next generation chemical priming: with a little help from our nanocarrier friends

Plants are exposed to multiple threats linked to climate change which can cause critical yield losses. Therefore, designing novel crop management tools is crucial. Chemical priming has recently emerged as an effective technology for improving tolerance to stress factors. Several compounds such as phytohormones, reactive species, and synthetic chimeras have been identified as promising priming agents. Following remarkable developments in nanotechnology, several unique nanocarriers (NCs) have been engineered that can act as smart delivery systems. These provide an eco-friendly, next-generation method for chemical priming, leading to increased efficiency and reduced overall chemical usage. We review novel engineered NCs (NENCs) as vehicles for chemical agents in advanced priming strategies, and address challenges and opportunities to be met towards achieving sustainable agriculture.

Dynamic interplay of metal and metal oxide nanoparticles with plants: Influencing factors, action mechanisms, and assessment of stimulatory and inhibitory effects

Nanoparticles (NPs) of metals and metal oxides have received increasing attention regarding their characteristic behavior in plant systems. The fate and transport of metal NPs and metal oxide NPs in plants is of emerging concern for researchers because they ultimately become part of the food chain. The widespread use of metal-based NPs (MBNPs) in plants has revealed their beneficial and harmful effects. This review addresses the main factors affecting the uptake, translocation, absorption, bioavailability, toxicity, and accumulation of MBNPs in different plant species. It appraises the mechanism of nanoparticle-plant interaction in detail and provides understanding of the estimation strategies for the associated pros and cons with this interplay. Critical parameters of NPs include, but are not limited to, particle size and shape, surface chemistry, surface charge, concentration, solubility, and exposure route. On exposure to MBNPs, the molecular, physiological, and biochemical reactions of plants have been assessed. We have filled knowledge gaps and answered research questions regarding the positive and negative effects of metal and metal oxide NPs on seed germination, callus induction, growth and yield of plant, nutritional content, antioxidants, and enzymes. Besides, the phytotoxicity, cytotoxicity, genotoxicity, and detoxification studies of MBNPs in plants have been outlined. Furthermore, the recent developments and future perspectives of the two-way traffic of interplay of MBNPs and plants have been provided in this comprehensive review.

Exploring the nano-wonders: unveiling the role of Nanoparticles in enhancing salinity and drought tolerance in plants

Plants experience diverse abiotic stresses, encompassing low or high temperature, drought, water logging and salinity. The challenge of maintaining worldwide crop cultivation and food sustenance becomes particularly serious due to drought and salinity stress. Sustainable agriculture has significant promise with the use of nano-biotechnology. Nanoparticles (NPs) have evolved into remarkable assets to improve agricultural productivity under the robust climate alteration and increasing drought and salinity stress severity. Drought and salinity stress adversely impact plant development, and physiological and metabolic pathways, leading to disturbances in cell membranes, antioxidant activities, photosynthetic system, and nutrient uptake. NPs protect the membrane and photosynthetic apparatus, enhance photosynthetic efficiency, optimize hormone and phenolic levels, boost nutrient intake and antioxidant activities, and regulate gene expression, thereby strengthening plant's resilience to drought and salinity stress. In this paper, we explored the classification of NPs and their biological effects, nanoparticle absorption, plant toxicity, the relationship between NPs and genetic engineering, their molecular pathways, impact of NPs in salinity and drought stress tolerance because the effects of NPs vary with size, shape, structure, and concentration. We emphasized several areas of research that need to be addressed in future investigations. This comprehensive review will be a valuable resource for upcoming researchers who wish to embrace nanotechnology as an environmentally friendly approach for enhancing drought and salinity tolerance.

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.

Uptake and transport of micro/nanoplastics in terrestrial plants: Detection, mechanisms, and influencing factors

The pervasive dispersion of micro/nanoplastics in various environmental matrices has raised concerns regarding their potential intrusion into terrestrial ecosystems and, notably, plants. In this comprehensive review, we focus on the interaction between these minute plastic particles and plants. We delve into the current methodologies available for detecting micro/nanoplastics in plant tissues, assess the accumulation and distribution of these particles within roots, stems, and leaves, and elucidate the specific uptake and transport mechanisms, including endocytosis, apoplastic transport, crack-entry mode, and stomatal entry. Moreover, uptake and transport of micro/nanoplastics are complex processes influenced by multiple factors, including particle size, surface charge, mechanical properties, and physiological characteristics of plants, as well as external environmental conditions. In conclusion, this review paper provided valuable insights into the current understanding of these mechanisms, highlighting the complexity of the processes and the multitude of factors that can influence them. Further research in this area is warranted to fully comprehend the fate of micro/nanoplastics in plants and their implications for environmental sustainability.

Transport of Nanoparticles into Plants and Their Detection Methods

Nanoparticle transport into plants is an evolving field of research with diverse applications in agriculture and biotechnology. This article provides an overview of the challenges and prospects associated with the transport of nanoparticles in plants, focusing on delivery methods and the detection of nanoparticles within plant tissues. Passive and assisted delivery methods, including the use of roots and leaves as introduction sites, are discussed, along with their respective advantages and limitations. The barriers encountered in nanoparticle delivery to plants are highlighted, emphasizing the need for innovative approaches (e.g., the stem as a new recognition site) to optimize transport efficiency. In recent years, research efforts have intensified, leading to an evendeeper understanding of the intricate mechanisms governing the interaction of nanomaterials with plant tissues and cells. Investigations into the uptake pathways and translocation mechanisms within plants have revealed nuanced responses to different types of nanoparticles. Additionally, this article delves into the importance of detection methods for studying nanoparticle localization and quantification within plant tissues. Various techniques are presented as valuable tools for comprehensively understanding nanoparticle-plant interactions. The reliance on multiple detection methods for data validation is emphasized to enhance the reliability of the research findings. The future outlooks of this field are explored, including the potential use of alternative introduction sites, such as stems, and the continued development of nanoparticle formulations that improve adhesion and penetration. By addressing these challenges and fostering multidisciplinary research, the field of nanoparticle transport in plants is poised to make significant contributions to sustainable agriculture and environmental management.