Abstract
These days, research in agriculture is focusing on the theme of sustainability along with protection of agriculture produce. Nanotechnology in the agriculture sector aims for the enhancement of agricultural produce and the reduction of pesticides through providing innovative agrochemical agents and their novel delivery mechanisms. The current investigation involved the green synthesis of silver nanoparticles (AgNPs) from the aqueous leaf extract of Melia azedarach by following a microwave-assisted method to control Fusarium oxysporum, the causal agent of tomato wilt. Biosynthesized Melia leaf extract (MLE)-AgNPs were characterized by UV-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectrometry, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential analysis. The intensity of the peak at 434 nm in UV-vis spectra, attributed to the surface plasmon resonance of MLE-AgNPs, changes with reaction parameters. TEM exhibits spherical shaped nanoparticles with an average particle size range from 12 to 46 nm. Efficient inhibition of F. oxysporum, the causal agent of tomato wilt, was achieved after exposure to MLE-AgNPs both in vivo and in vitro. In vitro studies exhibited repressed fungal mycelial growth with 79–98% inhibition as compared to the control. Significant increases in growth parameters of tomato seedlings were observed after treatment with biosynthesized nanoparticles as compared to F. oxysporum-infected plants grown without them under greenhouse conditions. Furthermore, SEM imaging was done to reveal the prominent damage on the cell wall of hyphae and spores after MLE-AgNP treatment. Propidium iodide (PI) staining of mycelium indicated the extent of cell death, causing irretrievable damage and disintegration of cellular membranes by altering the membrane permeability. Also, 2′,7′-dichlorofluorescin diacetate (DCFH-DA) fluorescence specifies intracellular reactive oxygen species (ROS) production in F. oxysporum after treatment with MLE-AgNPs. The current investigation suggested that biosynthesized nanoparticles can revolutionize the field of plant pathology by introducing an environment-friendly approach for disease management and playing a potential part in agriculture industry. However, to date, little work has been done to integrate nanotechnology into phytopathology so, this area of research is in need of adoption and exploration for the management of plant diseases.
Highlights
The term “green synthesis” or “phytonanotechnology” has been coined for nanoparticle (NP) synthesis which has many advantages including its biocompatibility, scalability, and applicability by utilizing water which acts as a reduction medium (Noruzi, 2015)
The peak at 434 nm in UV-vis spectrum is attributed to the surface plasmon resonance (SPR) which is due to collective oscillations of the conduction of electrons of the MLEAgNPs in the reaction solution which gradually surges with the exposure time (Figure 2A)
It is indicated from the results that green synthesis of Melia leaf extract (MLE)-AgNPs was significantly accelerated by approaching microwave irradiation
Summary
The term “green synthesis” or “phytonanotechnology” has been coined for nanoparticle (NP) synthesis which has many advantages including its biocompatibility, scalability, and applicability by utilizing water which acts as a reduction medium (Noruzi, 2015). It has been recommended that vitamins, proteins, organic acids, amino acids, and secondary metabolites act like capping and stabilizing agents that reduce metal salts of synthesized NPs by playing a key role (Duan et al, 2015). Being an eco-friendly and a multifactorial biogenic material, application of NPs is receiving attention due to their specific physiochemical properties, serves as an inexpensive approach for assembling of innovative functional materials used almost in every area of science and technology like medicine, engineering, environment, and agriculture (Austin et al, 2014; Majdalawieh et al, 2014; Siripattanakul-Ratpukdi and Furhacker, 2014; Prasad et al, 2016; Vishwakarma et al, 2017). Due to the interdynamic properties of NPs, there are high opportunities to explore the potential of NPs while the nano-elicitive behavior of these minute particles may rely on their nature and methods of synthesis (Jasim et al, 2017)
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