Green synthesis and evaluation of silver nanoparticles for antimicrobial and biochemical profiling in Kinnow (Citrus reticulata L.) to enhance fruit quality and productivity under biotic stress

Insecticide Efficacy of Green Synthesis Silver Nanoparticles on Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of Liberibacter asiaticus Jagoueix et al. and Liberibacter americanus Teixeira et al., causal agents of the critical yellow dragon disease or Huanglongbing (HLB), which affects citrus production worldwide. Recently, green synthetic nanoparticles have emerged as a potential alternative to control of agricultural insect pests. The insecticide effect of silver nanoparticles (AgNPs) on 2nd instar nymphs of D. citri under laboratory and greenhouse conditions was evaluated. Mortality was recorded 24, 48, and 72 h after application on D. citri nymphs under both laboratory and greenhouse conditions. The laboratory results showed that AgNPs caused 97.84 and 100% mortality at 32 and 64 ppm, respectively, 72 h after treatment. In the greenhouse, AgNPs caused 78.69 and 80.14% mortality using 64 and 128 ppm 72 h after application. This research is the first to evaluate the green synthesis AgNPs on D. citri and are a promising strategy to control the pest.

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.

Nanobiotechnology in crop stress management: an overview of novel applications

Agricultural crops are subject to a variety of biotic and abiotic stresses that adversely affect growth and reduce the yield of crop plantss. Traditional crop stress management approaches are not capable of fulfilling the food demand of the human population which is projected to reach 10 billion by 2050. Nanobiotechnology is the application of nanotechnology in biological fields and has emerged as a sustainable approach to enhancing agricultural productivity by alleviating various plant stresses. This article reviews innovations in nanobiotechnology and its role in promoting plant growth and enhancing plant resistance/tolerance against biotic and abiotic stresses and the underlying mechanisms. Nanoparticles, synthesized through various approaches (physical, chemical and biological), induce plant resistance against these stresses by strengthening the physical barriers, improving plant photosynthesis and activating plant defense mechanisms. The nanoparticles can also upregulate the expression of stress-related genes by increasing anti-stress compounds and activating the expression of defense-related genes. The unique physico-chemical characteristics of nanoparticles enhance biochemical activity and effectiveness to cause diverse impacts on plants. Molecular mechanisms of nanobiotechnology-induced tolerance to abiotic and biotic stresses have also been highlighted. Further research is needed on efficient synthesis methods, optimization of nanoparticle dosages, application techniques and integration with other technologies, and a better understanding of their fate in agricultural systems.

Bio-Fabrication of Euryale ferox (Makhana) Leaf Silver Nanoparticles and Their Antibacterial, Antioxidant and Cytotoxic Potential

Bio-fabrication of green or plant extract-based silver nanoparticles has garnered much praise over the past decade as the methodology is environment-friendly, undemanding, non-pathogenic, and economical. In the current study, leaves of Eurale ferox (Makhana), considered as waste, were used for the bio-fabrication of silver nanoparticles (ELAgNPs). Various analytical techniques including UV−VIS spectroscopy, Field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (FESEM-EDX), Particle size analyzer (PSA), Fourier transform infra-red spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM) were used for their characterization. Their antibacterial efficacy was examined against gram positive bacterium, Bacillus subtilis and gram negative bacterium, Escherichia coli. The antioxidant potential of the ELAgNPs was compassed by 2, 2 diphenyl-1-picryl hydrazyl (DPPH; λmax = 517 nm) assay, H2O2 (λmax = 230 nm) and OH− (λmax = 520 nm)-based radical scavenging assays. The cytotoxicity was checked against the VERO cell line using 3-[4, 5-dimethyl thiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay. A mean particle size of 26.51 ± 8.87 nm with a size distribution of 7.08−53.94 nm was obtained using HRTEM. The ELAgNPs exhibited dose-dependent antibacterial efficacy with a maximum zone of inhibition (ZOI) of 21.98 ± 0.59 mm against B. subtilis and of 16.46 ± 0.22 mm against E. coli at 500 ppm after 24 h of incubation. The median lethal concentration for the cytotoxicity analysis was found to be 9.54 ± 0.35 ppm, 120.9 ± 6.31 ppm, and 20.74 ± 0.63 ppm for ELAgNPs, commercial silver nanoparticles (CAgNPs), and silver nitrate (SN), respectively. The ordinary one-way ANOVA results exhibited a significant decrease in cell viability after 72 h of incubation at p < 0.05, α = 0.05. In conclusion, the ELAgNPs showed good antibacterial, radical scavenging and dose-dependent cytotoxicity against the VERO cells. Therefore, these could be used for biomedical applications. Phyto-constituents present in the plant not only act as reducing agents but also as stabilizing and coating agents, and the availability of a wide range of metabolites makes the green approach more promising.