Growth, physiological and molecular response of calcium and salicylic acid primed wheat under lead stress.

Background: Heavy metal contamination, particularly from lead (Pb), poses a significant threat to plant agriculture worldwide, adversely affecting growth, physiological functions, and yield. Signalling molecules such as calcium and salicylic acid are known to mitigate various stresses in plants, prompting this study to explore their interaction with Pb stress in wheat.

Methods: A pot experiment was conducted in which wheat grains were primed with either distilled water, 5 mM calcium (Ca), or 0.05 mM salicylic acid (SA) for 12 h. Following germination, seedlings were exposed to 100 mM Pb six days later, while the control group received water irrigation. Growth parameters, physiological changes, molecular responses, and yield characteristics were assessed to understand the impact of the treatments.

Results: The application of Ca and SA acid significantly ameliorated Pb-induced reductions in growth parameters, yield criteria, and phenolic content. These treatments also reduced oxidative stress by restoring osmoprotectants, Pb ion content, and antioxidant enzyme activities to normal levels. Additionally, they downregulated genes that were overexpressed in Pb-stressed wheat.

Conclusions: Ca and SA treatments effectively mitigate lead toxicity in wheat by protecting growth, enhancing physiological resilience, and maintaining productivity. These findings suggest that leveraging chemical stimulants such as calcium and salicylic acid constitutes a viable strategy for reducing the detrimental impacts of heavy metal stress on crop yields.