The toxic effects of aluminum (Al) ions on plant roots were identified over a century ago. However, the effects of Al oxide nanoparticles (Al2O3 NPs) on plant growth and development are poorly understood. In the present study, plant interactions with Al2O3 NPs were systematically evaluated from seed germination and root growth to full maturity by measuring biomass and uptake of Al and nutrients of lettuce plants. The plants were grown in hydroponic solutions with varying concentrations of Al2O3 NPs (0, 0.4, 1, and 2 mg/mL) or AlCl3 (0, 0.04, 0.4, and 1 mg/mL). The results suggest that Al2O3 NPs had a neutral or positive influence on seed germination and root elongation, whereas AlCl3 treatment resulted in a significant reduction in emerging root lengths. Upon harvest, lettuce plants exposed to Al2O3 NPs of 1 and 2 mg/mL showed 10.4% and 30.4% decreases in biomass, whereas exposure to AlCl3 of 0.4 and 1 mg/mL reduced plant biomass to 22.3% and 9.96% respectively. In both treatments, Al uptake by roots increased linearly; however, translocation of Al2O3 NPs into shoots was limited, whereas translocation of AlCl3 increased with increasing treatment concentration. Furthermore, significant adsorption and/or aggregation of Al2O3 NPs on the root surfaces appears to affect plant uptake of macronutrients, but not micronutrients. Calcium uptake was the most inhibited by AlCl3. The translocation of Al2O3 NPs from roots to stems and leaves were also visually confirmed by fluorescently-labeled Al2O3 NPs with fluorescence and confocal laser scanning microscopic techniques. These findings demonstrated that Al2O3 NPs behave differently from Al ions when interacting plants under hydroponic conditions. Thus, it is concluded that Al2O3 NPs pose less phytotoxicity than AlCl3, primarily due to NPs role on stimulated root growth, significant adsorption/aggregation on roots, limited lateral translocation to shoots and leaves, as well as enhanced uptake of essential nutrients.

Plant interactions with engineered aluminum oxide nanoparticles

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.