Enhancing Cadmium Tolerance in Common Bean Plants by Seed Priming with Putrescine

This study evaluates the efficacy of putrescine-based seed biopriming at concentrations of 0, 0.25, 0.5, and 1 mmol in mitigating oxidative stress induced by 50 mg kg⁻¹ cadmium (Cd) in common bean plants. Cadmium exposure significantly elevated oxidative stress markers, such as hydrogen peroxide (H₂O₂), while suppressing antioxidative enzyme activities, including ascorbate peroxidase (APX). Putrescine treatments, particularly at 0.5 and 1 mmol, enhanced antioxidative defenses by increasing superoxide dismutase (SOD) and APX activities and reducing H₂O₂ levels, thereby alleviating oxidative damage. Photosynthetic performance improved markedly with putrescine application, as evidenced by higher chlorophyll a content, an optimized chlorophyll a/b ratio, and increased total carotenoid levels, indicating enhanced photosynthetic efficiency under cadmium stress. Among the treatments, Cd-P3 (1 mmol putrescine) demonstrated the most significant improvements, reversing the detrimental effects of cadmium on photosynthetic pigments and plant health. Additionally, putrescine enhanced the accumulation of total phenolic and flavonoid compounds, contributing to improved antioxidant capacity. This was supported by higher DPPH radical scavenging activity and FRAP values, highlighting its strong antioxidative potential. In summary, putrescine seed priming offers a promising strategy for mitigating cadmium toxicity in plants. By modulating antioxidant systems, stabilizing photosynthetic pigments, and promoting bioactive compound synthesis, putrescine enhances plant resilience to heavy metal stress. These findings underscore its potential application in agricultural practices to improve crop tolerance to abiotic stresses.