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CeO2 nanoparticles alter the growth of soybeans and their root-associated microbiome in a non-monotonic, age-dependent manner
Citation:
Slattery, M., S. Harper, M. Johnson, C. Andersen, AND J. Reichman. CeO2 nanoparticles alter the growth of soybeans and their root-associated microbiome in a non-monotonic, age-dependent manner. 28th PNW-SETAC Annual Conference, Vancouver, WA, April 04 - 06, 2019.
Impact/Purpose:
Engineered nanoparticles (ENMs) are currently being used in a variety of consumer products due to their unique physical, chemical, and electrical properties. The properties that make these ENMs functionally unique also may influence their toxicity to organisms in ecosystems. CSS’s Emerging Materials research is designed to identify potential adverse molecular to system-level effects of these materials in the environment. Cerium oxide nanoparticles (CeNPs) used in fuel additives and other industrial products may result in the accumulation of these nanoparticles in terrestrial compartments. Biological interactions between CeNPs, plants, and the root-associated microbiome are poorly understood. Here, soybeans were grown to maturity in a natural soil with either aged CeNPs (3-month incubation in soil) or fresh CeNPs (no incubation in soil) at relatively low (1 ppm) or high (100 ppm) soil concentrations. CeNP exposures caused significant changes to the soybean nodule biomass, bean biomass, number of beans, stem biomass, and plant height, depending on the particle concentration and age. Root microbiome displayed dramatic shifts that were dependent on spatial proximity to the root surface and CeNP treatment. Impacts to soybeans and their root-associated microbiome were dependent on the concentration and age of CeNPs. Low concentration of CeNPs produced agriculturally and ecologically relevant changes in the plant-soil system. These results highlight the non-monotonic effects of CeNPs in soil that may change dramatically over time and the potential for microbiome-mediated plant toxicity.
Description:
The use of cerium oxide nanoparticles (CeNPs) in fuel additives and other industrial products may result in the accumulation of these nanoparticles in terrestrial compartments. The biological interaction between CeNPs, plants, and the root-associated microbiome is poorly understood. Complicating the issue, the use of pristine nanoparticles in toxicity tests may not be relevant considering the dynamic nature of nanoparticles in complex environmental media. Here, soybeans were grown to maturity in a natural soil with either aged CeNPs (3 month incubation in soil) or pristine CeNPs (no incubation in soil) at relatively low (1 ppm) or high (100 ppm) soil concentrations. CeNP exposures caused significant changes to the soybean nodule biomass, bean biomass, number of beans, stem biomass, and plant height, depending on the particle concentration and age. A non-monotonic response was apparent for some phenotypic endpoints, particularly among the pristine CeNPs. To identify associations between plant growth and the root-associated microbiome, root samples were processed for 16S rDNA amplicon sequencing. The root microbiome displayed dramatic shifts that were dependent on spatial proximity to the root surface and CeNP treatment. Bradyrhizobiacae, a family of symbiotic nitrogen fixing bacteria, were significantly elevated in soybean treatments which showed increased nodule biomass. Pristine CeNPs increased community evenness while fundamentally altering the taxonomic structure. The aged CeNPs did not display this strong deviation from the community baseline, despite a significant loss of richness when compared to the control. Overall, impacts to soybeans and their root-associated microbiome are dependent on the concentration and age of CeNPs. In this case, a relatively low concentration of CeNPs produced agriculturally and ecologically relevant changes in the plant-soil system. These results highlight the non-monotonic effects of CeNPs in soil that may change dramatically over time and the potential for microbiome-mediated plant toxicity.