Aluminum oxide (Al2O3) nanoparticles (NPs) are currently ranked second in total market production, accounting for approximately 20% of all nanomaterials manufacturing and production. However, the behavior of Al2O3 NPs in biological processes and natural ecosystems has not been extensively investigated. Especially, very few studies have considered their interaction with terrestrial plant species, particularly for fully mature plants destined for consumption. In this study, we examined the effects of Al2O3 NPs on onion, carrot, lettuce and soybean plants by measuring growth responses from seedling germination and root growth to full maturity as a function of Al2O3 NPs. Commercially-available, spherical 10 nm gamma-Al2O3 NPs were used to evaluate bioavailability of Al2O3 NPs, whereas AlCl3 was used as a treatment control at equivalent Al concentrations. Among the four plant species tested, only lettuce and carrot showed a statistically significant decrease in seed germination rate and root growth with increasing concentration of Al2O3 NPs (P &lt; 0.0004 for lettuce, P &lt; 0.0007 for carrot). Significant inhibition by AlCl3 upon seed germination and root growth was observed in all the plant species. Uptake, translocation and accumulation of Al2O3 NPs in plants were studied using lettuce, because lettuce exhibited a treatment effect to both Al2O3 NPs and AlCl3. Plant biomass decreased and Al content in leaf tissue increased with increasing Al2O3 NPs concentration reflecting the NPs’ toxic effects upon plant growth. Scanning electron microscopy (SEM) analysis on thin sections of mature lettuce leaf tissue showed that spherical aggregates located inside the leaf tissue layers contained Al, suggesting Al bioaccumulation in the mature lettuce leaf harvested from Al2O3 NP-spiked soils. Thus, commercial Al2O3 NPs adversely interact with selected plants through multiple plant development stages, from decreasing rates of seed germination and root growth to increasing Al bioaccumulation in fully mature leaves that are intended for human consumption.

Uptake, distribution, and effects of nano alumina in terrestrial plants at the cellular and macro-scale levels

252nd National Meeting (2016)

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