Interplay of Melatonin and Jasmonic Acid in Modulating Wheat (Triticum aestivum L.) Physiology and Molecular Pathways Under Salt Stress

The objective of this study was to evaluate the effectiveness of melatonin (Mel) and jasmonic acid (JA) in enhancing wheat seedlings’ adaptation to salt stress through physiological and genetic parameters. Wheat seedlings were divided into experimental groups exposed to salt stress (TS) and treated with exogenously applied Mel, JA, or a combination of both (Mel + JA) via hand spraying. Pigment analysis was performed to measure total chlorophyll, chlorophyll a, and the chlorophyll a/b ratio. Total protein levels were quantified, and malondialdehyde (MDA) content was assessed as an indicator of lipid peroxidation. RAPD assay and qPCR analysis were conducted to evaluate both DNA damage and gene expressions response. Experimental groups exposed to salt stress were treated with exogenous Mel, JA, or a combination of Mel and JA. In pigment analysis, total chlorophyll, chlorophyll a, and the chlorophyll a/b ratio significantly decreased under salt stress (TS) but approached normal levels, particularly in the combined TS + Mel and TS + JA + Mel treatments. Physiological parameters, including chlorophyll pigment levels, generally decreased under salt stress but increased with JA and Mel treatments. Total protein content significantly increased under salt stress but decreased substantially in the combined treatment groups. Notably, the expression of antioxidant genes such as APX, CuZnSOD, GPX, MnSOD, and CAT, along with HSP and transcription factor expressions, showed minimal activity in the TS + JA + Mel combined treatment. Morphologically, the TS + JA + Mel group closely resembled the control group. Our findings indicate that the synergistic application of JA and Mel holds promise as an effective treatment strategy for enhancing the resilience of wheat seedlings under salt stress.