Abstract
Silver is an important and efficient bactericide. Nanoscale silver has a large specific surface area, high target adhesion, strong permeability and high bactericidal activity. At present, the control of plant bacterial diseases is difficult, and the resistance of plant bacterial pathogens develops rapidly. Silver nanoparticles are expected to become a new generation of agrochemical to control plant bacterial diseases. In this study, a simple and green natural sunlight-induced method was used to prepare carboxymethylcellulose sodium-stabilized silver nanoparticles (CMC-SNs) with a particle size of around 13.53 ± 4.72 nm. CMC-SNs were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD) and UV-vis spectroscopy and found to be spherical and evenly dispersed. The bacteriostatic activity of the CMC-SNs toward Xanthomonas oryzae pv. oryzae (Xoo) was tested. The minimum inhibitory concentration (MIC) of CMC-SNs to Xoo was 1 mg/L, and the minimum bactericidal concentration (MBC) was 2 mg/L. In addition, the antibacterial mechanism was studied by scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM), which confirmed that the CMC-SNs had high antibacterial activity. In order to verify its impact on the environment, we conducted an acute toxicity test on zebrafish and found that Half lethal concentration (LC50) > 100 mg/L in zebrafish, or no acute toxicity. The ability of CMC-SNs to control rice bacterial blight was verified by a pot experiment.
Highlights
At present, plant bacterial diseases cause huge economic losses in the world every year
The size distribution of carboxymethylcellulose sodium-stabilized silver nanoparticles (CMC-SNs) prepared by this method is around 15 nm, which has good dispersion and a uniform shape
The results of bioassays show that the CMC-SNs have high antibacterial activity against the pathogenic bacteria of rice bacterial blight, Pseudomonas avenae Manns and rice bacterial sheath rot
Summary
Plant bacterial diseases cause huge economic losses in the world every year. Copper compounds introduced in the 1880s and streptomycin introduced in the 1950s are the main agents used to control plant bacterial diseases. Numerous plant bacterial pathogens have developed different levels of resistance to copper compounds and streptomycin [2,3]. The bacteriostatic ability of the silver ion is slightly higher than that of silver nanoparticles [5], but at the same time, the damage of silver ions to plasma membranes and proteins makes it highly toxic to humans, the environment and other organisms. Nano-silver has a larger specific surface area; nano-sliver particles are capable of penetrating the cell membrane or attaching to the bacterial surface based on their smaller size, so their bactericidal activity, permeability and transmissibility are better than streptomycin and copper compounds [2]. Through the pot experiment of Oryza sativa L. (rice), it was shown that the CMC-SNs have good prospects in the application of rice bacterial disease control
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