Comparative Analysis of Nano-Bactericides and Thiodiazole-Copper on Tomato Rhizosphere Microbiome

Abstract

Vegetable crops such as tomato are highly susceptible to various pathogens. Nanoparticles (NPs) are emerging as effective nano-bactericides for managing plant pathogens. Communities of rhizosphere bacteria are essential for plant physiological health and also serve as a critical factor in evaluating the environmental compatibility of NPs. We evaluated the effects of a nano-bactericide (Cu-Ag nanoparticles) and a commercial bactericide (thiodiazole-copper) on the rhizosphere microbiome of tomato. The results show that low and high doses of the two bactericides induced alterations in the bacterial community structure to differing extents. Cu-Ag nanoparticles increased the relative abundance of potentially beneficial bacteria, including Bacteroidota, Gemmatimonadota, Acidobacteriota, and Actinobacteriota. Functional prediction revealed that Cu-Ag nanoparticles may affect the metabolic pathways of tomato root rhizosphere microorganisms and regulate the lacI/galR family, which controls virulence factors and bacterial metabolism. This study provides insight into the influence of metal nanoparticles on plant rhizosphere microbiomes and may lay a foundation for the application of nano-bactericides for the environmentally friendly control of plant diseases.

Keywords: microbial community; nano-bactericide; nanoparticles; rhizosphere; tomato.

Figure 1

Unique ASVs in Cu-Ag nanoparticles treated group compared to control tomato ASVs (a). Unique ASVs in thiodiazole–copper treated group compared to control tomato ASVs (b). Unique ASVs between different concentrations of thiodiazole–copper treated group, nanomaterials group and control tomatoes ASVs (c). Abbreviations: Tomato plants only treated with the water (S1). Tomato treated with low dosages of Cu-Ag nanoparticles (S2). Tomato treated with high dosages of Cu-Ag nanoparticles (S3). Tomato treated with low dosages of thiodiazole–copper (S4). Tomato treated with high dosages of thiodiazole–copper (S5).

Figure 2

Chao1 (a) and Shannon (b) index of tomato under the exposure of low and high dosages of thiodiazole–copper and Cu-Ag nanoparticles nanomaterials. Error bars showing the mean of four replicates. Statistical significance was determined based on Tukey’s HSD test. * p < 0.05.

Figure 3

Community clustering of bacteria under different treatments was visualized in a two-dimensional NMDS plot based on a Bray–Curtis matrix (a). Principal coordinate analysis (PCoA) based on the Bray–Curtis index dissimilarity of tomato treated with Cu-Ag nanoparticles (b). PCoA analysis of tomato samples and tomato treated thiodiazole–copper (c).

Figure 4

Effect of thiodiazole–copper and Cu-Ag nanoparticles on the bacterial community abundance of tomato. Relative abundance distribution of the top 15 microbial phyla (a) and the top 20 bacterial genera (b) in the rhizosphere of all tomato samples.

Figure 5

Linear discriminant analysis effect size (LEfSe) of bacteria. Significantly different abundant taxa of tomato rhizosphere from Cu-Ag nanoparticles treatments (a,b) and thiodiazole–copper treatments (c,d). The dimensions of the colored dots correspond to the relative abundance of the bacteria. The figure presents species that exhibit notable differences. Abbreviations: c: class; o: order; f: family; g: genus; s: species.

Figure 6

The bacterial community networks in the tomato treated with nano-bactericide (a). The community networks in the tomato treated thiodiazole–copper (b). The number of nodes, edges, and the clustering coefficients are shown in the networks, and the nodes are colored according to phylum. Pink and blue lines represent negative and positive associations, respectively.