The potential of glycine betaine application to combat Cd and As toxicity in wheat plants by altering photosynthetic, physiological, and antioxidant enzyme indices

Arsenic (As) and cadmium (Cd) are significant pollutants known for their extreme toxicity to plants. In the past few decades, anthropogenic activities and industrial discharges have released enormous quantities of As and Cd. This has threatened sustainable farming practices and restricted diverse plant species' overall profit potential. Many osmoprotectants are renowned for mitigating the adverse effects of Cd and As toxicity on plants. Glycine betaine (GB) is a vital osmoregulator whose levels vary significantly from plant to plant under stress. The present study examined the impact of exogenous GB application on Cd and As tolerance in potted culture-grown wheat (HD2967 and HD3086) using Cd and As (1100 ppm and 225 ppm) and two levels of GB (0 and 5 mM). The results delineated that Cd and As stress caused a significant reduction in photosynthetic pigments, chlorophyll stability index (CSI), and water content in both wheat varieties. However, the electrolyte leakage (EL) content increases in coupled with different antioxidant enzyme activities (POX, CAT, and SOD) under Cd and As stress in response to ROS accumulation. GB application alleviated As and Cd toxicity by activating antioxidant enzyme-coding genes, and the ROS removal permitted a higher level of chlorophyll, thereby reducing the adverse effects of stress. Further, GB treatments enhanced the activities of antioxidant enzymes which helped to counteract As and Cd exposure. Also, GB reduced the oxidative stress in both roots and leaves by reducing EL levels. Hence, the current study indicates that GB shows excellent potential as a biostimulant to enhance Cd and As stress tolerance in wheat plants. This research offers a scientific framework for evaluating the tolerance of wheat plants to stress caused by Cd and As, as well as for devising alternative strategies to shield them from the harmful impacts of Cd and As toxicity.