Carbon nanotubes as plant growth regulators: Effects on tomato growth, reproductive system, and soil microbial community

Multi-walled carbon nanotubes (CNTs) can affect plant phenotype and the composition of soil microbiota. Tomato plants grown in soil supplemented with CNTs produce two times more flowers and fruit compared to plants grown in control soil. The effect of carbon nanotubes on microbial community of CNT-treated soil is determined by denaturing gradient gel electrophoresis and pyrosequencing analysis. Phylogenetic analysis indicates that Proteobacteria and Bacteroidetes are the most dominant groups in the microbial community of soil. The relative abundances of Bacteroidetes and Firmicutes are found to increase, whereas Proteobacteria and Verrucomicorbia decrease with increasing concentration of CNTs. The results of comparing diversity indices and species level phylotypes (OTUs) between samples showed that there is not a significant affect on bacterial diversity. Carbon nanotubes (CNTs) can affect plant phenotype. Tomato plants grown on soil supplemented with CNTs produce two times more flowers and fruit than plants grown in regular soil. Comparative metagenomic analysis of microbial communities of CNT-treated soils reveals that the diversity and richness of microbial communities is not affected by CNTs, while the abundance of each bacterial group is influenced by treatment of CNTs.