Application of Silicon with Salicylic Acid Up-Regulate Physio-Biochemical Mechanisms of Wheat in Conferring Tolerance to Arsenic Induced Oxidative Stress

Arsenic (As) threatens plant growth and human health because its harmful effects are intensified by its persistent presence in the ecosystem. The absorption of As from the contaminated soil leads to accumulation in grains of food crops posing a serious threat to human health. High concentration of As hindered essential physio-biochemical processes of plants that ultimately diminish the growth and yield of crops. Therefore; a pot study was designed to assess synergistic effect of silicon (Si) and salicylic acid (SA) (control-Ck, 4.0 mM Si, 150 µM SA, 4.0 mM Si + 150 µM SA) in mitigating the adversities of As stress in wheat seedlings exposed to As stress (0, and 100 μM). Wheat seedlings exposed to As showed a significant decline in morphological attributes as well as photosynthetic pigments (chlorophyll a, b and carotenoids). However; foliar application of Si and SA considerably increased morphological parameters and leaf photosynthetic pigments under As stress. The imposition of As resulted in enhance accumulation of hydrogen peroxide, MDA, and electrolyte leakage, increased activities of enzymatic antioxidants (superoxide dismutase, peroxidase, and ascorbate peroxidase and catalase) and an elevated accumulation of essential organic osmolytes (free proline, soluble protein, total soluble sugar, total phenolics) in leaves of wheat seedlings. Furthermore, the application of Si + SA resulted in a remarkable increase in the activities of enzymatic antioxidants and accumulation of organic osmolytes. Simultaneously, it reduced the concentration of hydrogen peroxide, MDA, and electrolyte leakage in As-stress wheat seedlings. Under As-stress, sole and combined application of Si and SA caused a significant reduction in arsenic concentration while enhance Si contents in root and shoot of wheat seedlings. In conclusion, synergistic interaction between Si and SA could alleviate the negative impact of As by enhancing the antioxidant defense system, photosynthetic pigments, facilitating osmotic adjustment, and reducing the lipid peroxidation in maize seedlings. The current findings suggest that the combined exogenous application of Si and SA represent a promising approach for promoting the successful cultivation of wheat in As contaminated soil.

Graphical Abstract