Soil contamination with nickel (Ni) is a persistent threat to crop production worldwide. The present study examined the putative roles of jasmonic acid (JA) in improving Ni tolerance in soybean. Our findings showed that priming of soybean seeds with JA significantly improved the growth performance of soybean when grown under excessive Ni. The enhanced Ni tolerance of soybean prompted by JA could be ascribed to its ability to regulate Ni uptake and accumulation, and to decrease Ni-induced membrane damage as evidenced by reduced levels of reactive oxygen species (ROS), malondialdehyde, lipoxygenase activity, and electrolyte leakage in Ni-stressed plants. JA also boosted redox states and antioxidant capacity in Ni-stressed plants by maintaining increased levels of ascorbate and glutathione, and enhanced activities of ROS-detoxifying enzymes compared with Ni-stressed alone plants. Additionally, methylglyoxal detoxification system was significantly upregulated in JA-primed and “JA-primed + Ni-stressed” plants, indicating an alleviating effect of JA on Ni-induced methylglyoxal toxicity. Our results conclude that JA-mediated regulation of Ni uptake and accumulation, and enhanced ROS metabolism by activating antioxidant defense and glyoxalase systems contributed to improved performance of soybean under excessive Ni, thereby suggesting JA as an effective stress regulator in mitigating Ni toxicity in economically important soybean, and perhaps in other crops.
