Biogenic Silver Nanoparticles as a Stress Alleviator in Plants: A Mechanistic Overview

Effect of hyaluronic acid-stabilized silver nanoparticles on lettuce (Lactuca sativa L.) seed germination

Nanotechnology has brought significant advancements to agriculture through the development of engineered nanomaterials (ENPs). Silver nanoparticles (AgNPs) capped with polysaccharides have been applied in agricultural diagnostics, crop pest management, and seed priming. Hyaluronic acid (HA), a natural polysaccharide with bactericidal properties, has been considered a growth regulator for plant tissues and an inducer of systemic resistance against plant diseases. Additionally, HA has been employed as a stabilizing agent for AgNPs. This study investigated the synthesis and effects of hyaluronic acid-stabilized silver nanoparticles (HA-AgNPs) as a seed priming agent on lettuce (Lactuca sativa L.) seed germination. HA-AgNPs were characterized using several techniques, exhibiting spherical morphology and good colloidal stability. Germination assays conducted with 0.1, 0.04, and 0.02 g/L of HA-AgNPs showed a concentration-dependent reduction in seed germination. Conversely, lower concentrations of HA-AgNPs significantly increased germination rates, survival, tolerance indices, and seed water absorption compared to silver ions (Ag+). SEM/EDS indicated more significant potential for HA-AgNPs internalization compared to Ag+. Therefore, these findings are innovative and open new avenues for understanding the impact of Ag+ and HA-AgNPs on seed germination.

Biological Nano-Agrochemicals for Crop Production as an Emerging Way to Address Heat and Associated Stresses

Climate change is a global problem facing all aspects of the agricultural sector. Heat stress due to increasing atmospheric temperature is one of the most common climate change impacts on agriculture. Heat stress has direct effects on crop production, along with indirect effects through associated problems such as drought, salinity, and pathogenic stresses. Approaches reported to be effective to mitigate heat stress include nano-management. Nano-agrochemicals such as nanofertilizers and nanopesticides are emerging approaches that have shown promise against heat stress, particularly biogenic nano-sources. Nanomaterials are favorable for crop production due to their low toxicity and eco-friendly action. This review focuses on the different stresses associated with heat stress and their impacts on crop production. Nano-management of crops under heat stress, including the application of biogenic nanofertilizers and nanopesticides, are discussed. The potential and limitations of these biogenic nano-agrochemicals are reviewed. Potential nanotoxicity problems need more investigation at the local, national, and global levels, as well as additional studies into biogenic nano-agrochemicals and their effects on soil, plant, and microbial properties and processes.

Biogenic metallic nanoparticles: from green synthesis to clinical translation

Biogenic metallic nanoparticles (NPs) have garnered significant attention in recent years due to their unique properties and various applications in different fields. NPs, including gold, silver, zinc oxide, copper, titanium, and magnesium oxide NPs, have attracted considerable interest. Green synthesis approaches, utilizing natural products, offer advantages such as sustainability and environmental friendliness. The theranostics applications of these NPs hold immense significance in the fields of medicine and diagnostics. The review explores intricate cellular uptake pathways, internalization dynamics, reactive oxygen species generation, and ensuing inflammatory responses, shedding light on the intricate mechanisms governing their behaviour at a molecular level. Intriguingly, biogenic metallic NPs exhibit a wide array of applications in medicine, including but not limited to anti-inflammatory, anticancer, anti-diabetic, anti-plasmodial, antiviral properties and radical scavenging efficacy. Their potential in personalized medicine stands out, with a focus on tailoring treatments to individual patients based on these NPs' unique attributes and targeted delivery capabilities. The article culminates in emphasizing the role of biogenic metallic NPs in shaping the landscape of personalized medicine. Harnessing their unique properties for tailored therapeutics, diagnostics and targeted interventions, these NPs pave the way for a paradigm shift in healthcare, promising enhanced efficacy and reduced adverse effects.

Emerging trends to replace pesticides with nanomaterials: Recent experiences and future perspectives for ecofriendly environment

Despite the widespread usage to safeguard crops and manage pests, pesticides have detrimental effects on the environment and human health. The necessity to find sustainable agricultural techniques and meet the growing demand for food production has spurred the quest for pesticide substitutes other than traditional ones. The unique qualities of nanotechnology, including its high surface area-to-volume ratio, controlled release, and better stability, have made it a promising choice for pest management. Over the past ten years, there has been a noticeable growth in the usage of nanomaterials for pest management; however, concerns about their possible effects on the environment and human health have also surfaced. The purpose of this review paper is to give a broad overview of the worldwide trends and environmental effects of using nanomaterials in place of pesticides. The various types of nanomaterials, their characteristics, and their possible application in crop protection are covered. The limits of the current regulatory frameworks for nanomaterials in agriculture are further highlighted in this review. Additionally, it describes how standard testing procedures must be followed to assess the effects of nanomaterials on the environment and human health before their commercialization. In order to establish sustainable and secure nanotechnology-based pest control techniques, the review concludes by highlighting the significance of taking into account the possible hazards and benefits of nanomaterials for pest management and the necessity of an integrated approach. It also emphasizes the importance of more investigation into the behavior and environmental fate of nanomaterials to guarantee their safe and efficient application in agriculture.

Nanoparticles as a Tool for Alleviating Plant Stress: Mechanisms, Implications, and Challenges

Plants, being sessile, are continuously exposed to varietal environmental stressors, which consequently induce various bio-physiological changes in plants that hinder their growth and development. Oxidative stress is one of the undesirable consequences in plants triggered due to imbalance in their antioxidant defense system. Biochemical studies suggest that nanoparticles are known to affect the antioxidant system, photosynthesis, and DNA expression in plants. In addition, they are known to boost the capacity of antioxidant systems, thereby contributing to the tolerance of plants to oxidative stress. This review study attempts to present the overview of the role of nanoparticles in plant growth and development, especially emphasizing their role as antioxidants. Furthermore, the review delves into the intricate connections between nanoparticles and plant signaling pathways, highlighting their influence on gene expression and stress-responsive mechanisms. Finally, the implications of nanoparticle-assisted antioxidant strategies in sustainable agriculture, considering their potential to enhance crop yield, stress tolerance, and overall plant resilience, are discussed.

Nanotechnology for controlling mango malformation: a promising approach

Mango (Mangifera indica L.) is one of the most important fruit crops in the world with yields of approximately 40 million tons annually and its production continues to decrease every year as a result of the attack of certain pathogens i.e. Colletotrichum gloeosporioides, Erythricium salmonicolor, Amritodus atkinsoni, Idioscopus clypealis, Idioscopus nitidulus, Bactrocera obliqua, Bactrocera frauenfeldi, Xanthomonas campestris, and Fusarium mangiferae. So F. mangiferae is the most harmful pathogen that causes mango malformation disease in mango which decreases its 90% yield. Nanotechnology is an eco-friendly and has a promising effect over traditional methods to cure fungal diseases. Different nanoparticles possess antifungal potential in terms of controlling the fungal diseases in plants but applications of nanotechnology in plant disease managements is minimal. The main focus of this review is to highlight the previous and current strategies to control mango malformation and highlights the promising applications of nanomaterials in combating mango malformation. Hence, the present review aims to provide brief information on the disease and effective management strategies.Communicated by Ramaswamy H. Sarma.

A Combinatorial Nanobased Spray-Induced Gene Silencing Technique for Crop Protection and Improvement

Recent research reports have shown that plant pests and pathogens have depleted the crop yield widely, which has led to an increased dependence on commercial pesticides and fungicides. Increased usage of these pesticides has also shown adverse effects on the environment, therefore many techniques have been implemented for solving the issue, some of which include using nanobioconjugates, RNA(i), which put into use double-stranded RNAs to inhibit gene expression. A more innovative and eco-friendly strategy includes spray induced gene silencing, which is being increasingly implemented. This review delves into the eco-friendly approach of spray induced gene silencing (SIGS) in combination with nanobioconjugates, which have been used concerning various plant hosts and their pathogens to provide improved protection. Furthermore, nanotechnological advancements have been understood by addressing the scientific gaps to provide a rationale for the development of updated techniques in crop protection.

Biogenic synthesis of silver nanoparticles using Funaria hygrometrica Hedw. and their effects on the growth of Zea mays seedlings

The biogenic synthesis of silver nanoparticles (AgNPs) is an important step in developing eco-friendly and environmentally stable tools for ameliorating crop growth. In the current study, AgNPs were synthesized using Funaria hygrometrica and characterized using ultraviolet (UV) spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). The UV spectrum showed an absorption peak at 450 nm. SEM revealed an irregular and spherical morphology, FTIR spectroscopy indicated the presence of various functional groups, while XRD displayed peaks at 45.24°, 38.17°, 44.34°, 64.54°, and 57.48° 2θ. The effects of the F. hygrometrica-mediated AgNPs on maize growth and germination were assessed at 0, 100, 300, and 500 ppm. The germination percentage and relative germination rate were increased to 95% ± 1.83% and 100% ± 2.48% at 100 ppm of synthesized AgNPs and then declined at 300 and 500 ppm. The length, fresh weight, and dry matter of the root, shoot, and seedlings were highest at 100 ppm NPs. The plant height, root length, and dry matter stress tolerance indices were also the highest (112.3%, 118.7%, and 138.20% compared with the control) at 100 ppm AgNPs. Moreover, the growth of three maize varieties, that is, NR-429, NR-449, and Borlog, were assessed at 0, 20, 40, and 60 ppm F. hygrometrica-AgNPs. The results indicated the highest root and shoot length at 20 ppm AgNPs. In conclusion, seed priming with AgNPs enhances the growth and germination of maize and can ameliorate crop production globally. RESEARCH HIGHLIGHTS: Funaria hygrometrica Hedw.-mediated AgNPs were synthesized and characterized. Biogenic AgNPs influenced the growth and germination of maize seedlings. All growth parameters were highest at 100 ppm synthesized NPs.

Phytomediated Silver Nanoparticles (AgNPs) Embellish Antioxidant Defense System, Ameliorating HLB-Diseased 'Kinnow' Mandarin Plants

Citrus production is harmed worldwide by yellow dragon disease, also known as Huanglongbing (HLB), or citrus greening. As a result, it has negative effects and a significant impact on the agro-industrial sector. There is still no viable biocompatible treatment for Huanglongbing, despite enormous efforts to combat this disease and decrease its detrimental effects on citrus production. Nowadays, green-synthesized nanoparticles are gaining attention for their use in controlling various crop diseases. This research is the first scientific approach to examine the potential of phylogenic silver nanoparticles (AgNPs) to restore the health of Huanglongbing-diseased 'Kinnow' mandarin plants in a biocompatible manner. AgNPs were synthesized using Moringa oleifera as a reducing, capping, and stabilizing agent and characterized using different characterization techniques, i.e., UV-visible spectroscopy with a maximum average peak at 418 nm, scanning electron microscopy (SEM) with a size of 74 nm, and energy-dispersive spectroscopy (EDX), which confirmed the presence of silver ions along with different elements, and Fourier transform infrared spectroscopy served to confirm different functional groups of elements. Exogenously, AgNPs at various concentrations, i.e., 25, 50, 75, and 100 mgL^-1, were applied against Huanglongbing-diseased plants to evaluate the physiological, biochemical, and fruit parameters. The findings of the current study revealed that 75 mgL^-1 AgNPs were most effective in boosting the plants' physiological profiles, i.e., chl a, chl b, total chl, carotenoid content, MSI, and RWC up to 92.87%, 93.36%, 66.72%, 80.95%, 59.61%, and 79.55%, respectively; biochemical parameters, i.e., 75 mgL^-1 concentration decreased the proline content by up to 40.98%, and increased the SSC, SOD, POD, CAT, TPC, and TFC content by 74.75%, 72.86%, 93.76%, 76.41%, 73.98%, and 92.85%, respectively; and fruit parameters, i.e., 75 mgL^-1 concentration increased the average fruit weight, peel diameter, peel weight, juice weight, rag weight, juice pH, total soluble solids, and total sugarby up to 90.78%, 8.65%, 68.06%, 84.74%, 74.66%, 52.58%, 72.94%, and 69.69%, respectively. These findings enable us to develop the AgNP formulation as a potential citrus Huanglongbing disease management method.

Metabolomics as a Tool to Understand Nano-Plant Interactions: The Case Study of Metal-Based Nanoparticles

Metabolomics is a powerful tool in diverse research areas, enabling an understanding of the response of organisms, such as plants, to external factors, their resistance and tolerance mechanisms against stressors, the biochemical changes and signals during plant development, and the role of specialized metabolites. Despite its advantages, metabolomics is still underused in areas such as nano-plant interactions. Nanoparticles (NPs) are all around us and have a great potential to improve and revolutionize the agri-food sector and modernize agriculture. They can drive precision and sustainability in agriculture as they can act as fertilizers, improve plant performance, protect or defend, mitigate environmental stresses, and/or remediate soil contaminants. Given their high applicability, an in-depth understanding of NPs' impact on plants and their mechanistic action is crucial. Being aware that, in nano-plant interaction work, metabolomics is much less addressed than physiology, and that it is lacking a comprehensive review focusing on metabolomics, this review gathers the information available concerning the metabolomic tools used in studies focused on NP-plant interactions, highlighting the impact of metal-based NPs on plant metabolome, metabolite reconfiguration, and the reprogramming of metabolic pathways.