Different Physiological and Biochemical Responses of Bamboo to the Addition of TiO2 NPs under Heavy Metal Toxicity

Abstract

Bamboo forests cover a remarkable area of Chinese forestland. Recently, titanium dioxide nanoparticles (TiO2 NPs) have been used for plant protection against abiotic stress. In this study, an in vitro tissue culture experiment was conducted to determine the impact of titanium on plant tolerance to two different heavy metals (Cu and Pb). Bamboo plants (Arundinaria pygmaea L.) were grown using five concentrations of TiO2 NPS (0, 50, 80, 100, and 150 µM) without or with 100 µM Cu and 100 µM Pb for 30 days. The results showed that while Cu and Pb increased the generation of Reactive oxygen species (ROS) compounds in plants, TiO2 NP treatments played a positive role in reducing oxidative stress, as indicated by the decrease in ROS compounds, the extent of lipoperoxidation, and soluble proteins. On the other hand, the use of TiO2 NPs increased the total antioxidant capacity, chlorophyll content and general plant biomass. Moreover, the addition of TiO2 NPs significantly reduced Cu, and Pb accumulation in roots, stems, and shoots. We concluded that TiO2 NPs have the ability to reduce oxidative stress in plants by increasing the antioxidant capacity, improving the level of injury, and protecting cell membranes via reducing lipoperoxidation (reduction of Malondialdehyde (MDA) content). However, the results indicated that the efficiency of TiO2 NPs was related to the type and concentration of heavy metal, as TiO2 NPs were more effective for Cu than Pb. Additionally, a high concentration of TiO2 NPs resulted in the greatest enhancement in plant growth and development under heavy metal stress.