Nanotechnology: A New Opportunity in Plant Sciences

Wheat chronic exposure to TiO2-nanoparticles: Cyto- and genotoxic approach

This study investigates the phytotoxicity of chronic exposure (up to 20 d) of different TiO₂ nanoparticles (TiO₂-NP) concentrations (5, 50, 150 mg L^-1) in Triticum aestivum. Germination was not affected by TiO₂-NP exposure and seedling shoot length (3 d) was enhanced. Contrarily, plants' shoot growth (20 d) was impaired. Effects on membrane permeability and total antioxidant capacity in TiO₂-NP chronic exposure were organ dependent: increased in leaves and decreased in roots. Roots also showed lower levels of lipid peroxidation. Flow cytometry revealed no changes in ploidy levels as well as in the cell cycle dynamics for both organs. However, TiO₂-NP induced clastogenic effects in roots with increases in micronucleated cells in root tips in a dose dependent manner. Also, increases of DNA single/double strand breaks were found in leaves, and effects were similar to all doses. Ti uptake and translocation to leaves were confirmed by ICP-MS, which was dependent on NP concentration. Overall, these data indicate that TiO₂-NP phytotoxicity is more severe after longer exposure periods, higher doses and more severe for shoots than roots. The observed effects are a result of both direct and indirect (oxidative stress and/or water imbalances) action of TiO₂-NP. Additionally, results highlight the negative impact that TiO₂-NP may have on crop growth and production and to the risk of trophic transfer.

Endocytic pathways involved in PLGA nanoparticle uptake by grapevine cells and role of cell wall and membrane in size selection

PLGA NPs' cell uptake involves different endocytic pathways. Clathrin-independent endocytosis is the main internalization route. The cell wall plays a more prominent role than the plasma membrane in NPs' size selection. In the last years, many studies on absorption and cell uptake of nanoparticles by plants have been conducted, but the understanding of the internalization mechanisms is still largely unknown. In this study, polydispersed and monodispersed poly(lactic-co-glycolic) acid nanoparticles (PLGA NPs) were synthesized, and a strategy combining the use of transmission electron microscopy (TEM), confocal analysis, fluorescently labeled PLGA NPs, a probe for endocytic vesicles (FM4-64), and endocytosis inhibitors (i.e., wortmannin, ikarugamycin, and salicylic acid) was employed to shed light on PLGA NP cell uptake in grapevine cultured cells and to assess the role of the cell wall and plasma membrane in size selection of PLGA NPs. The ability of PLGA NPs to cross the cell wall and membrane was confirmed by TEM and fluorescence microscopy. A strong adhesion of PLGA NPs to the outer side of the cell wall was observed, presumably due to electrostatic interactions. Confocal microscopy and treatment with endocytosis inhibitors suggested the involvement of both clathrin-dependent and clathrin-independent endocytosis in cell uptake of PLGA NPs and the latter appeared to be the main internalization pathway. Experiments on grapevine protoplasts revealed that the cell wall plays a more prominent role than the plasma membrane in size selection of PLGA NPs. While the cell wall prevents the uptake of PLGA NPs with diameters over 50 nm, the plasma membrane can be crossed by PLGA NPs with a diameter of 500-600 nm.

Anionic Cerium Oxide Nanoparticles Protect Plant Photosynthesis from Abiotic Stress by Scavenging Reactive Oxygen Species

Plant abiotic stress leads to accumulation of reactive oxygen species (ROS) and a consequent decrease in photosynthetic performance. We demonstrate that a plant nanobionics approach of localizing negatively charged, sub-11 nm, spherical cerium oxide nanoparticles (nanoceria) inside chloroplasts in vivo augments ROS scavenging and photosynthesis of Arabidopsis thaliana plants under excess light (2000 μmol m^-2 s^-1, 1.5 h), heat (35 °C, 2.5 h), and dark chilling (4 °C, 5 days). Poly(acrylic acid) nanoceria (PNC) with a hydrodynamic diameter (10.3 nm)-lower than the maximum plant cell wall porosity-and negative ζ-potential (-16.9 mV) exhibit significantly higher colocalization (46%) with chloroplasts in leaf mesophyll cells than aminated nanoceria (ANC) (27%) of similar size (12.6 nm) but positive charge (9.7 mV). Nanoceria are transported into chloroplasts via nonendocytic pathways, influenced by the electrochemical gradient of the plasma membrane potential. PNC with a low Ce³⁺/Ce⁴⁺ ratio (35.0%) reduce leaf ROS levels by 52%, including hydrogen peroxide, superoxide anion, and hydroxyl radicals. For the latter ROS, there is no known plant enzyme scavenger. Plants embedded with these PNC that were exposed to abiotic stress exhibit an increase up to 19% in quantum yield of photosystem II, 67% in carbon assimilation rates, and 61% in Rubisco carboxylation rates relative to plants without nanoparticles. In contrast, PNC with high Ce³⁺/Ce⁴⁺ ratio (60.8%) increase overall leaf ROS levels and do not protect photosynthesis from oxidative damage during abiotic stress. This study demonstrates that anionic, spherical, sub-11 nm PNC with low Ce³⁺/Ce⁴⁺ ratio can act as a tool to study the impact of oxidative stress on plant photosynthesis and to protect plants from abiotic stress.

Melatonin Improves the Photosynthetic Carbon Assimilation and Antioxidant Capacity in Wheat Exposed to Nano-ZnO Stress

The release of nanoparticles into the environment is inevitable, which has raised global environmental concern. Melatonin is involved in various stress responses in plants. The present study investigated the effects of melatonin on photosynthetic carbon (C) assimilation and plant growth in nano-ZnO stressed plants. It was found that melatonin improved the photosynthetic C assimilation in nano-ZnO stressed wheat plants, mainly due to the enhanced photosynthetic energy transport efficiency, higher chlorophyll concentration and higher activities of Rubisco and ATPases. In addition, melatonin enhanced the activities of antioxidant enzymes to protect the photosynthetic electron transport system in wheat leaves against the oxidative burst caused by nano-ZnO stress. These results suggest that melatonin could improve the tolerance of wheat plants to nano-ZnO stress.

Impact of Metal and Metal Oxide Nanoparticles on Plant: A Critical Review

An increasing need of nanotechnology in various industries may cause a huge environment dispersion of nanoparticles in coming years. A concern about nanoparticles interaction with flora and fauna is raised due to a growing load of it in the environment. In recent years, several investigators have shown impact of nanoparticles on plant growth and their accumulation in food source. This review examines the research performed in the last decade to show how metal and metal oxide nanoparticles are influencing the plant metabolism. We addressed here, the impact of nanoparticle on plant in relation to its size, concentration, and exposure methodology. Based on the available reports, we proposed oxidative burst as a general mechanism through which the toxic effects of nanoparticles are spread in plants. This review summarizes the current understanding and the future possibilities of plant-nanoparticle research.

Polymeric Nanoparticles as a Metolachlor Carrier: Water-Based Formulation for Hydrophobic Pesticides and Absorption by Plants

Pesticide formulation is highly desirable for effective utilization of pesticide and environmental pollution reduction. Studies of pesticide delivery system such as microcapsules are developing prosperously. In this work, we chose polymeric nanoparticles as a pesticide delivery system and metolachlor was used as a hydrophobic pesticide model to study water-based mPEG-PLGA nanoparticle formulation. Preparation, characterization results showed that the resulting nanoparticles enhanced "water solubility" of hydrophobic metolachlor and contained no organic solvent or surfactant, which represent one of the most important sources of pesticide pollution. After the release study, absorption of Cy5-labeled nanoparticles into rice roots suggested a possible transmitting pathway of this metolachlor formulation and increased utilization of metolachlor. Furthermore, the bioassay test demonstrated that this nanoparticle showed higher effect than non-nano forms under relatively low concentrations on Oryza sativa, Digitaria sanguinalis. In addition, a simple cytotoxicity test involving metolachlor and metolachlor-loaded nanoparticles was performed, indicating toxicity reduction of the latter to the preosteoblast cell line. All of these results showed that those polymeric nanoparticles could serve as a pesticide carrier with lower environmental impact, comparable effect, and effective delivery.

Impact of Surface Charge on Cerium Oxide Nanoparticle Uptake and Translocation by Wheat (Triticum aestivum)

Nanoparticle (NP) physiochemical properties, including surface charge, affect cellular uptake, translocation, and tissue localization. To evaluate the influence of surface charge on NP uptake by plants, wheat seedlings were hydroponically exposed to 20 mg/L of ∼4 nm CeO₂ NPs functionalized with positively charged, negatively charged, and neutral dextran coatings. Fresh, hydrated roots and leaves were analyzed at various time points over 34 h using fluorescence X-ray absorption near-edge spectroscopy to provide laterally resolved spatial distribution and speciation of Ce. A 15-20% reduction from Ce(IV) to Ce(III) was observed in both roots and leaves, independent of NP surface charge. Because of its higher affinity with negatively charged cell walls, CeO₂(+) NPs adhered to the plant roots the strongest. After 34 h, CeO₂(-), and CeO₂(0) NP exposed plants had higher Ce leaf concentrations than the plants exposed to CeO₂(+) NPs. Whereas Ce was found mostly in the leaf veins of the CeO₂(-) NP exposed plant, Ce was found in clusters in the nonvascular leaf tissue of the CeO₂(0) NP exposed plant. These results provide important information for understanding mechanisms responsible for plant uptake, transformation, and translocation of NPs, and suggest that NP coatings can be designed to target NPs to specific parts of plants.

Nanosensor Technology Applied to Living Plant Systems

An understanding of plant biology is essential to solving many long-standing global challenges, including sustainable and secure food production and the generation of renewable fuel sources. Nanosensor platforms, sensors with a characteristic dimension that is nanometer in scale, have emerged as important tools for monitoring plant signaling pathways and metabolism that are nondestructive, minimally invasive, and capable of real-time analysis. This review outlines the recent advances in nanotechnology that enable these platforms, including the measurement of chemical fluxes even at the single-molecule level. Applications of nanosensors to plant biology are discussed in the context of nutrient management, disease assessment, food production, detection of DNA proteins, and the regulation of plant hormones. Current trends and future needs are discussed with respect to the emerging trends of precision agriculture, urban farming, and plant nanobionics.

Cu Nanoparticles in Hydrogels of Chitosan-PVA Affects the Characteristics of Post-Harvest and Bioactive Compounds of Jalapeño Pepper

Peppers are consumed all over the world due to the flavor, aroma, and color that they add to food. Additionally, they play a role in human health, as they contain a high concentration of bioactive compounds and antioxidants. The treatments used were an absolute control, Cs-PVA, and four treatments with 0.02, 0.2, 2, and 10 mg (nCu) g⁻¹ (Cs-PVA). The application of Cu nanoparticles in chitosan-PVA hydrogels increases the content of capsaicin by up to 51% compared to the control. This application also increases the content of antioxidants ABTS [2,2′-azino-bis (3-ethylbenzothiazolin-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl), total phenols and flavonoids (4%, 6.6%, 5.9%, and 12.7%, respectively) in jalapeño pepper fruits stored for 15 days at room temperature; under refrigeration, it increases DPPH antioxidants, total phenols, and flavonoids (23.9%, 1.54%, and 17.2%, respectively). The application of Cu nanoparticles in chitosan-PVA hydrogels, even when applied to the substrate, not only has an effect on the development of the jalapeño pepper crop, but also modifies the post-harvest characteristics of the jalapeño pepper fruits.

Nanosheets for Delivery of Biomolecules into Plant Cells

Layered double hydroxides (LDHs) are sheet-formed nanoparticles (NPs) of adjustable size. It has recently been reported that LDHs have the ability to deliver biomolecules into intact plant cells. LDHs show promise as a novel and powerful tool for plant cell studies and similar applications.

Effects of exposure pathways on the accumulation and phytotoxicity of silver nanoparticles in soybean and rice

The widespread use of silver nanoparticles (AgNPs) raises concerns both about their accumulation in crops and human exposure via crop consumption. Plants take up AgNPs through their leaves and roots, but foliar uptake has been largely ignored. To better understand AgNPs-plant interactions, we compared the uptake, phytotoxicity and size distribution of AgNPs in soybean and rice following root versus foliar exposure. At similar AgNP application levels, foliar exposure led to 17-200 times more Ag bioaccumulation than root exposure. Root but not foliar exposure significantly reduced plant biomass, while root exposure increased the malondialdehyde and H2O2 contents of leaves to a larger extent than did foliar exposure. Following either root or foliar exposure, Ag-containing NPs larger (36.0-48.9 nm) than the originally dosed NPs (17-18 nm) were detected within leaves. These particles were detected using a newly developed macerozyme R-10 tissue extraction method followed by single-particle inductively coupled plasma mass spectrometry. In response to foliar exposure, these NPs were stored in the cell wall and plamalemma of leaves. NPs were also detected in planta following Ag ion exposure, indicating their in vivo formation. Leaf-to-leaf and root-to-leaf translocation of NPs in planta was observed but the former did not alter the size distribution of the NPs. Our observations point to the possibility that fruits, seeds and other edible parts may become contaminated by translocation processes in plants exposed to AgNPs. These results are an important contribution to improve the risk assessment of NPs under environmental exposure scenarios.

Low-dose toxicity of biogenic silver nanoparticles fabricated by Swertia chirata on root tips and flower buds of Allium cepa

Chemically synthesized silver nanoparticles (chem-AgNPs) have been assessed extensively to show adverse effects on plant cells but the role of biologically synthesized nanoparticles (bio-AgNPs) at lower concentrations and their toxicological impact on plant cells have not been sufficiently studied. In this study, bio-AgNPs were prepared using aqueous leaf extracts of Swertia chirata. This AgNPs showed absorption peak at 440nm of the visible spectrum. TEM analysis revealed that the average size of AgNPs were 20nm and mainly spherical in shape. AFM topographic images depicted the three dimensional aspects of AgNPs. XRD analysis confirmed the crystalline nature. FTIR spectrum of the AgNPs revealed the possible biomolecules involved in bioreduction and efficient stabilization of the particles. Low-dose of bio-AgNPs concentrations (5, 10 and 20μgml^-1) were used for toxicity studies on Allium cepa. The studies revealed that various chromosomal aberrations were induced in both mitotic and meiotic cells of Allium cepa even at lower concentrations of bio-AgNPs. Abnormalities in post meiotic products were also observed. Both mitotic and meiotic indexes decreased with increasing concentrations of bio-AgNPs in the treated cells. These findings implied that low dose bio-AgNPs can induce significant clastogenic effects on both meristematic and reproductive plant cells.

Nanoparticles based on essential metals and their phytotoxicity

Nanomaterials in agriculture are becoming popular due to the impressive advantages of these particles. However, their bioavailability and toxicity are key features for their massive employment. Herein, we comprehensively summarize the latest findings on the phytotoxicity of nanomaterial products based on essential metals used in plant protection. The metal nanoparticles (NPs) synthesized from essential metals belong to the most commonly manufactured types of nanomaterials since they have unique physical and chemical properties and are used in agricultural and biotechnological applications, which are discussed. The paper discusses the interactions of nanomaterials and vascular plants, which are the subject of intensive research because plants closely interact with soil, water, and atmosphere; they are also part of the food chain. Regarding the accumulation of NPs in the plant body, their quantification and localization is still very unclear and further research in this area is necessary.

Surface Acoustic Waves to Drive Plant Transpiration

Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals-as well as the primary vehicle for current e-plant and phtyo-nanotechnology work-we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems.

Does seed size and surface anatomy play role in combating phytotoxicity of nanoparticles?

Rapid utilization of nano-based products will inevitably release nanoparticles into the environment with unidentified consequences. Plants, being an integral part of ecosystem play a vital role in the incorporation of nanoparticles in food chain and thus, need to be critically assessed. The present study assesses the comparative phytotoxicity of nanoparticle, bulk and ionic forms of zinc at different concentrations on selected plant species with varying seed size and surface anatomy. ZnO nanoparticles were chosen in view of their wide spread use in cosmetics and health care products, which allow their direct release in the environment. The impact on germination rate, shoot & root length and vigour index were evaluated. A concentration dependent inhibition of seed germination as well as seedling length was observed in all the tested plants. Due to the presence of thick cuticle on testa and root, pearl millet (xerophytic plant) was found to be relatively less sensitive to ZnO nanoparticles as compared to wheat and tomato (mesophytic plants) with normal cuticle layer. No correlation was observed between nanoparticles toxicity and seed size. The results indicated that variations in surface anatomy of seeds play a crucial role in determining the phytotoxicity of nanoparticles. The present findings significantly contribute to assess potential consequences of nanoparticle release in environment particularly with major emphasis on plant systems. It is the first report which suggests that variations observed in phytotoxicity of nanoparticles is mainly due to the predominant differences in size and surface anatomy of tested plant seeds and root architecture. Effect of various concentrations of nano ZnO, bulk ZnO and zinc sulphate on the growth of pearl millet (A), tomato (B) and wheat (C) seedlings.

Case Study of Somaclonal Variation in Resistance Genes Mlo and Pme3 in Flaxseed (Linum usitatissimum L.) Induced by Nanoparticles

Nanoparticles influence on genome is investigated worldwide. The appearance of somaclonal variation is a cause of great concern for any micropropagation system. Somaclonal variation describes the tissue-culture-induced phenotypic and genotypic variations. This paper shows the results of somaclonal variation in two resistance genes pectin methylesterase and Mlo-like protein in all tissue culture development stages, as donor plant, calluses, and regenerants of Linum usitatissimum induced by gold and silver nanoparticles. In this paper, it was essential to obtain DNA material from all tissue culture development stages from one donor plant to record changes in each nucleotide sequence. Gene region specific primers were developed for resistance genes such as Mlo and Pme3 to define the genetic variability in tissue culture of L. usitatissimum. In recent years, utilization of gold and silver nanoparticles in tissue culture is increased and the mechanisms of changes in genome induced by nanoparticles still remain unclear. Obtained data show the somaclonal variation increase in calluses obtained from one donor plant and grown on medium supplemented by gold nanoparticles (Mlo 14.68 ± 0.98; Pme3 2.07 ± 0.87) or silver nanoparticles (Mlo 12.01 ± 0.43; Pme3 10.04 ± 0.46) and decrease in regenerants. Morphological parameters of calluses showed a number of differences between each investigated culture group.

Nanomaterials in plant tissue culture: the disclosed and undisclosed

Nanomaterial integration into tissue culture for prospective uninterrupted progressive plant tissue culture.

Pollen derived blue fluorescent carbon dots for bioimaging and monitoring of nitrogen, phosphorus and potassium uptake in Brassica parachinensis L

Carbon dots (CDs), synthesized from biological sources, have attracted attention in bioimaging and bioscience due to their low cytotoxicity, water-soluble nature, and biocompatibility.

Oral Toxicity and Intestinal Transport Mechanism of Colloidal Gold Nanoparticle-Treated Red Ginseng

(1) Background: Application of nanotechnology or nanomaterials in agricultural food crops has attracted increasing attention with regard to improving crop production, quality, and nutrient utilization. Gold nanoparticles (Au-NPs) have been reported to enhance seed yield, germination rate, and anti-oxidant potential in food crops, raising concerns about their toxicity potential. In this study, we evaluated the oral toxicity of red ginseng exposed to colloidal Au-NPs during cultivation (G-red ginseng) in rats and their intestinal transport mechanism. (2) Methods: 14-day repeated oral administration of G-red ginseng extract to rats was performed, and body weight, hematological, serum biochemical, and histopathological values were analyzed. An in vitro model of human intestinal follicle-associated epithelium (FAE) and an intestinal epithelial monolayer system were used for intestinal transport mechanistic study. (3) Results: No remarkable oral toxicity of G-red ginseng extract in rats was found, and Au-NPs did not accumulate in any organ, although Au-NP transfer to G-red ginseng and some increased saponin levels were confirmed. Au-NPs were transcytozed by microfold (M) cells, but not by a paracellular pathway in the intestinal epithelium. (4) Conclusion: These findings suggest great potential of Au-NPs for agricultural food crops at safe levels. Further study is required to elucidate the functional effects of Au-NPs on ginseng and long-term toxicity.