Evidence of the Differential Biotransformation and Genotoxicity of ZnO and CeO₂ Nanoparticles on Soybean (Glycine max) Plants

Abstract

Concern and interest related to the effects of nanomaterials on living organisms are growing in both the scientific and public communities. Reports have described the toxicity of nanoparticles (NPs) on micro and macro organisms, including some plant species. Nevertheless, to the authors' knowledge there are no reports on the biotransformation of NPs by edible terrestrial plants. Here, shown for the first time, is evidence pertaining to the biotransformation of ZnO and CeO 2 NPs in plant seedlings. Although the NPs did not affect soybean germination, they produced a differential effect on plant growth and element uptake. By using synchrotron X-ray absorption spectroscopy we obtained clear evidence of the presence of CeO 2 NPs in roots, whereas ZnO NPs were not present. Random amplified polymorphic DNA assay was applied to detect DNA damage and mutations caused by NPs. Results obtained from the exposure of soybean plants to CeO 2 NPs show the appearance of four new bands at 2000 mg L −1 and three new bands at 4000 mg L −1 treatment. In this study we demonstrated genotoxic effects from the exposure of soybean plants to CeO 2 NPs.

Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption

“…We learned that these MNMs entered and accumulated in plants, and thus are bioavailable in this farm soil. Ce was mobilized from soil and accumulated into the roots with uptake levels similar to those observed in a hydroponic study (24). However, our results show that root nodules also acquire nano-CeO 2 , a finding only made possible from studying soilgrown plants.…”

“…Such Zn concentrations in various plant tissues were similar for equivalently dosed soybean (on a Zn mass basis) grown with Zn salts (33). However, nano-ZnO must have been highly bioavailable in this study soil, as Zn also substantially bioaccumulated in nano-ZnO-treated plants in a previous hydroponic study (24). Very high Zn accumulations could cause long-term impacts to either plant or human health (SI Appendix), but the extent and relationship to Zn form (including nano-ZnO) in the plant are unknown.…”

“…Soybean plants were grown through the seed production stage in soil amended with nano-CeO 2 (0, 0.1, 0.5, or 1 g·kg −1 ) or nano-ZnO (0, 0.05, 0.1, or 0.5 g·kg −1 ). Similar concentrations of these nanoparticles affect hydroponic plants (24,27) and microorganisms (25,28), but the effects on soilcultivated food crop plants are heretofore unknown. Plant growth was monitored by measuring stem length, leaf count, and leaf cover; the latter estimates total leaf area, can indicate plant health, and is affected by water stress (29) and metal exposure (30).…”

“…Previous soil-grown soybean studies regarded metal salts (33,35), but studies examining plant-MNM interactions generally used aqueous exposure systems (24,(36)(37)(38). There has been contradictory evidence from studying soil microbial communities, i.e., that some MNMs are not bioavailable in soil (39), but also evidence to the contrary for other MNMs (25).…”

Curbing the Growth of Wax Bean (<i>Vigna unguiculata</i> L.) <i>via</i> a Novel Complex of Nano Zinc Oxide/Vermicompost

“…By increasing the amount of ZnO NPs, the grain yield decreased by 42% (Table 5). According to the results of Lopez et al (2010), probably ZnO NPs reduced soybean (Glycine max) root growth and nutrient uptake and also as the result of leaves chlorosis, photosynthesis and plant growth reduced. John et al (2009) reported that the bud's growth reduction under Cu or Zn stress may result from the water potential reduction, hampered nutrient uptake and secondary stress such as oxidative stress, that eventually leads to decrease in yield and yield components.…”