Urease-null soybean (eu3-a) under salt and copper stress: nitrogen metabolism, antioxidant defense, and arginine pathway genes

MAIN CONCLUSION: : 0, 10, and 50 µM) over a 5-day treatment period. The following parameters were assessed in leaf tissue: photosynthetic performance, antioxidant enzyme activity, levels of nitrogenous compounds, and the expression of genes encoding key enzymes in the arginine-derived metabolic network. Overall, salinity imposed more severe physiological disruptions than copper in both lines, as evidenced by an approximately 88% reduction in photosynthetic performance under 100 mM of salt. Both stresses impaired nitrogen metabolism, increasing ammonia levels and reducing nitrate concentration. Interestingly, eu3-a plants demonstrated enhanced tolerance to salt stress relative to Eu3 plants, but this trend was not observed under copper stress. Future work should address nitrogen-related enzymatic activities associated with urease metabolism and elucidate the non-enzymatic antioxidant mechanisms contributing to stress tolerance in eu3-a soybean plants under salt and copper stress.