Salicylic acid ameliorates zinc and chromium-induced stress responses in wheat seedlings: a biochemical and computational analysis

Abstract

The ameliorative effect of seed priming with salicylic acid (SA) on Cr⁶⁺ and Zn²⁺ induced stress responses in wheat (Triticum aestivum L.) was evaluated using biochemical and computational approaches. The results suggested that Cr⁶⁺ and Zn²⁺ stress in wheat seedlings in absence of SA priming resulted in significant inhibition of growth, biomass loss with high accumulation of reactive oxygen species (ROS) leading to oxidative stress and inactivation of antioxidant metabolism. Wheat seeds primed with SA ameliorated the effects of Cr⁶⁺ and Zn²⁺ induced stress by maintaining appropriate growth and biomass of the seedlings. Moreover, when compared to the SA non-primed wheat seedlings, the levels of ROS and oxidative stress load were low in SA-primed seedlings subjected to Cr⁶⁺ and Zn²⁺ stress, which clearly indicated an ameliorative effect of seed priming with SA. Though, significant variation of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) was not observed in wheat seedlings under stress conditions, and the non-enzymatic antioxidants such as ascorbic acid (AsA) and reduced glutathione (GSH) showed higher levels in SA-primed seedlings as compared to non-primed groups. The computational (molecular docking) analysis with Cu–Zn–SOD, Mn–SOD and CAT as target enzymes revealed that SA may potentially interfere with the binding and interaction of Cr⁶⁺ and Zn²⁺ ions with the active site of Cu–Zn–SOD effectively. Though, this computational analysis is based on structures of the targets derived through homology modeling, nevertheless it fundamentally substantiated our experimental findings on CAT and SOD activities.