Toxic Effects of Aluminum Oxide (Al2O3) Nanoparticles on Root Growth and Development in Triticum aestivum

The development of nanotechnology has increased the amount of nanoparticles in the environment inducing pollution. In view of increasing amounts, their toxicity assessment becomes important. Aluminum oxide nanoparticles (Al2O3 NPs) have a wide range of applications in industry. The present study aims to reveal the time-dependent (24, 48, 72, 96 h) and dose-dependent (0, 5, 25, 50 mg/ml) effects of 13-nm-sized Al2O3 NPs on an agronomic plant wheat (Triticum aestivum L.) roots correlating with the appearance of various cellular stress responses. Al2O3 NPs reduced the root elongation by 40.2 % in 5 mg/ml, 50.6 % in 25 mg/ml, and 54.5 % in 50 mg/ml after 96 h. Histochemical analysis revealed lignin accumulation, callose deposition, and cellular damage in root cortex cells correlating the root elongation inhibition. Although the nanoparticle application decreased the total protein content with respect to control after 96 h, the peroxidase activity increased significantly which is considered to be one of the oxidative stress factors. Moreover, agarose gel results revealed that Al2O3 NPs induced DNA fragmentation being one of the important markers of programmed cell death. In conclusion, direct exposure to Al2O3 NPs leads to phytotoxicity significantly in wheat roots culminating in morphological, cellular, and molecular alterations.