Molecular Defense Responses in Wheat against Lead Toxicity: The Protective Role of SA, Cu and Zn

Lead (Pb) is widely considered to be one of the most dangerous heavy metals contaminating the environment. The toxicity of Pb is of particular concern because it is not biodegradable and can therefore accumulate in the food chain, posing a serious risk to human and animal health. In particular, it is inevitable to investigate Pb toxicity to plants and ways to reduce this toxicity. The present study investigates the effects of Pb on the expression of metallothionein genes, miR398 target genes and pathogen-associated resistance gene in wheat cultivar Triticum aestivum L. cv. “Cetinel 2000,” which is sensitive to heavy metal stress. The study utilized the quantitative real-time polymerase chain reaction (qRT-PCR) technique to analyze the ameliorative effects of copper (Cu), zinc (Zn) and salicylic acid (SA) against Pb toxicity. The study revealed that the expression of genes varies between organs, with remedial treatments exerting a positive effect on their expression. The results also confirmed that physiological (relative water content, chlorophyll content and cell membrane damage) and biochemical (peroxidase, superoxide dismutase, catalase and malondialdehyde content) changes were observed as a result of Pb stress. Furthermore, it was demonstrated that Cu, Zn and SA treatments had ameliorative effects. The results indicate that SA, Cu and Zn treatments play an effective role in reducing toxicity against Pb stress by regulating gene expression and enzyme activities.