Uptake of TiO2 Nanoparticles was Linked to Variation in net Cation flux in Wheat Seedlings

Abstract

Titanium dioxide nanoparticles (TiO2 NPs) are ubiquitous in the environment and enter the terrestrial food chain via plant uptake. However, plant uptake behaviors of TiO2 NPs remain elusive. Here, the uptake kinetics of TiO2 NPs by wheat (Triticum aestivum L.) seedlings and the effects on cation flux in roots were examined in a hydroponic system. Uptake rate of TiO2 NPs ranged from 119.0 to 604.2mg kg- 1h- 1 within 8h exposure. NP uptake decreased by 83% and 47%, respectively, in the presence of sodium azide (NaN3) and carbonyl cyanide m-chlorophenylhydrazone (CCCP), indicating an energy-dependent uptake of TiO2 NPs. Moreover, accompanied with TiO2 NP uptake, net influx of Cd2+ decreased by 81%, while Na+ flux shifted from inflow to outflow at the meristematic zone of root. These findings provide valuable information for understanding plant uptake of TiO2 NPs.