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

Abolghassem Emamverdian,Yinfeng Xie,Farzad Mokhberdoran,Muthusamy Ramakrishnan,Yulong Ding,Zishan Ahmad

doi:10.3390/f12060759

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.

Highlights

Soil contamination with heavy metals caused by anthropogenic activities and natural processes is a major threat to human health as these metals can enter the human food chain [1]
This study aimed to address the environmental concerns related to heavy metals by investigating various responses of bamboo growth to the addition of TiO2 NPs under two different types of heavy metal stress (Cu and Pb) and to understand how bamboo species can respond to
The 150 μM TiO2 NPs × 100 μM Cu and Pb treatment had the greatest impact on the stimulation of antioxidant capacity, with 2.0, 1.8, 0.99, 3.1, 1.2, and 0.79-fold enhancements in SOD, POD, CAT, APX, glutathione reductase (GR), and phenylalanine ammonia-lyase (PAL) capacities, respectively, in comparison with those of the control treatment (Table 1)

Summary

Introduction

Soil contamination with heavy metals caused by anthropogenic activities and natural processes is a major threat to human health as these metals can enter the human food chain [1]. Cu and Pb are considered the most polluting and most toxic elements, respectively, in the farmland soils of China [2]. Copper excess can lead to the disruption of enzymatic activities and cell membrane permeability, eventually reducing respiration and photosynthetic efficiency [5]. The destructive impact of Pb reduces photosynthetic capacity [6] and inhibits shoot and root growth in plants. TiO2 NPs have the potential to ameliorate the deleterious effects of various stressful factors on the biochemical and physiological traits of plants [8].

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