A comparative study on ellagic acid's role in salt tolerance, growth, antioxidant system, photochemistry and nitrogen metabolism in wheat and chickpea

This study aims to evaluate the effectiveness of ellagic acid (EA) in mitigating stress induced by salt and enhancing the tolerance of wheat (a monocot) and chickpea (a dicot). The experiment included four treatment groups: a control (C), 12.5 μM EA application, 100 mM salt (NaCl-S) exposure, and a combined treatment with 12.5 μM EA and 100 mM salt (S + EA). Key physiological (e.g., photosynthetic efficiency: F_v/F_m, F_v/F_o, F_o/F_m), growth, and biochemical responses, including antioxidant enzyme activities (CAT, SOD, POX, APX, GST, GPX, NOX, GR, MDHAR, DHAR) and nitrogen metabolism enzymes (NR, GS, GOGAT, GDH), were evaluated to determine the role of exogenous EA in mitigating salt stress. The application of EA effectively mitigated salt stress in wheat and chickpea by enhancing the relative growth rate (RGR) and relative water content (RWC). EA reduced oxidative stress markers, lowering H₂O₂ levels by 16 % in wheat and 26 % in chickpea, and decreased TBARS content, particularly in wheat. Photosynthetic efficiency was stabilized, especially in wheat, as evidenced by improved OJIP parameters. Antioxidant enzyme activities (CAT, POX) increased in response to EA, with wheat showing greater activity under stress. EA partially restored nitrogen metabolism, with GS and GOGAT activities improving under combined EA and salt treatments, more prominently in wheat. EA enhanced redox homeostasis, with wheat showing a significant increase in tAsA/DHA (76 %) and GSH/GSSG (8 %) , while chickpea showed no change in tAsA/DHA and a decrease in GSH/GSSG under Salt + EA treatment. Overall, EA enhanced salt tolerance by strengthening antioxidant defenses, improving nitrogen assimilation, and stabilizing photosynthesis, with species-specific differences in response patterns.