Intergenerational responses of wheat (Triticum aestivum L.) to cerium oxide nanoparticles exposure
Citation:
Rico, C., M. Johnson, M. Marcus, AND C. Andersen. Intergenerational responses of wheat (Triticum aestivum L.) to cerium oxide nanoparticles exposure. Environmental Science: Nano. RSC Publishing, Cambridge, Uk, 4:700-711, (2017).
Impact/Purpose:
Engineered nanoparticles (ENMs) are used in a wide variety of consumer and industrial products due to their unique physical, chemical, and electrical properties. The same properties that make these particles highly valuable may impose unknown toxicity to organisms in ecosystems. CSS’s Emerging Materials research is designed to identify potential adverse effects of these materials in the environment, including toxicity to plants and animals. Ideally EPA would like to understand mechanisms of response to ENMs in order to develop predictive tools to evaluate new nanomaterials as they are developed. In order to understand the impacts of organism’s repeated exposure to nanomaterials, WED scientists exposed wheat (Triticum aestivum L.), a globally important cereal crop, to cerium oxide nanoparticles (nanoceria) for two generations (i.e. two full life cycles). Nanoceria persists in nanoparticulate form in soil that intergenerational nanoceria-plants interactions is highly possible. Analyses of plant’s physiology, phenology, and nutrient content confirmed the carry-over effects of nanoceria exposure from previous generation. Wheat plants that have been exposed for two consecutive generations had reduced uptake of cerium, iron and manganese in roots, and nitrogen isotope δ15N in grains. Repeated exposure to nanoceria also reduced the accumulations of calcium, potassium, phosphorus, manganese and magnesium in grains indicating that seed quality was compromised. These findings show the importance of intergenerational exposure as a tool for understanding long-term effects of ENMs in plants and other terrestrial organisms. This paper contributes to CSS 18.02.
Description:
The intergenerational impact of engineered nanomaterials in plants is a key knowledge gap in the literature. A soil microcosm study was performed to assess the effects of multi-generational exposure of wheat (Triticum aestivum L.) to cerium oxide nanoparticles (CeO2-NPs). Seeds from plants that were exposed to 0, 125, and 500 mg CeO2-NPs/kg soil (Ce-0, Ce-125 or Ce-500, respectively) in first generation (S1) were cultivated in factorial combinations of Ce-0, Ce-125 or Ce-500 to produce second generation (S2) plants. The factorial combinations for first/second generation treatments in Ce-125 were S1-Ce-0/S2-Ce-0, S1-Ce-0/S2-Ce-125, S1-Ce-125/S2-Ce-0 and S1-Ce-125/S2-Ce-125, and in Ce-500 were S1-Ce-0/S2-Ce-0, S1-Ce-0/S2-Ce-500, S1-Ce-500/S2-Ce-0 and S1-Ce-500/S2-Ce-500. Agronomic, elemental, and isotopic data were collected in second generation plants. Results showed that plants treated during the first generation only with either Ce-125 or Ce-500 (e.g. S1-Ce-125/S2-Ce-0 or S1-Ce-500/S2-Ce-0) had reduced accumulation of Ce (61 or 50%), Fe (49 or 58%) and Mn (34 or 41%) in roots, and δ15N (11 or 8%) in grains compared to the plants not treated in both generations (i.e. S1-Ce-0/S2-Ce-0). In addition, plants treated in both generations with Ce-125 (i.e. S1-Ce-125/S2-Ce-125) produced grains that had lower Mn, Ca, K, Mg and P relative to plants treated in the second generation only (i.e. S1-Ce-0/S2-Ce-125). The findings demonstrated that first generation exposure of wheat to CeO2-NPs affects the physiology and nutrient profile of the second generation plants. However, the lack of concentration-dependent responses indicate that complex physiological processes are involved which alter uptake and metabolism of CeO2-NPs in wheat.
