The trivalent cerium-induced cell death and alteration of ion flux in sweetpotato [Ipomoea batatas (L.) Lam

Abstract

The rare earth element cerium (Ce) in its several forms is extensively utilized in various fields, including nano-technology, agriculture, and the food industry. Due to its increasing unregulated usage, Ce is now a potential source of pollution and toxicity due to its excessive environmental accumulation. Unfortunately, analysis of the toxic effects of Ce in plants is still in its early stages. Herein, we investigated the effects of Ce3+ treatment on development-related indicators in sweetpotato. We found that a low concentration (10 mg/L) slightly improved oxidation resistance, while a high concentration (20–80 mg/L) negatively affected development and photosynthesis and triggered increases in reactive oxygen species (ROS) production, antioxidant enzyme activities, and malondialdehyde (MDA) content. Moreover, elevation and efflux of cytosolic Ca2+ and caspase-1-like activity were induced by high-concentration Ce3+ treatment. Finally, cell viability decreased as Ce3+ concentration increased. These results suggest that (1) a high Ce3+ concentration (20–80 mg/L) inhibits development and photosynthesis of sweetpotato and induces oxidative damage followed by lipid peroxidation in the root, (2) a caspase-1-like protease is induced by cytosolic Ca2+ and ROS overproduction to cause programmed cell death in the root, and (3) a high concentration of Ce3+ could trigger a hypothetical cell death pathway, wherein Ce3+ induces ROS production followed by cytosolic Ca2+ elevation, which activates caspase-1-like activity, which in turn leads to programmed cell death in the root of sweetpotato.