Synergistic effect of chelators and Herbaspirillum sp. GW103 on lead phytoextraction and its induced oxidative stress in Zea mays

Phytoremediation is an in situ, low-cost strategy for cleanup of the sites contaminated with heavy metals. Experiments were conducted to assess the impact of synthetic chelators and plant growth-promoting rhizosphere bacteria (Herbaspirillum sp. GW103) on heavy metal lead (Pb) uptake in Z.mays cultivated in Pb-contaminated soil. The present study investigated the Pb phytoaccumulation rate and plant antioxidant enzyme activities in Z.mays exposed to 100 mg/kg of PbNO₃. The combination of gluconic acid (GA) with Herbaspirillum sp. GW103 treatment showed higher Pb solubility (18.9 mg/kg) compared with other chelators. The chemical chelators showed the significant difference in phytoaccumulation as well as antioxidant enzyme activities. The antioxidant enzymes such as catalase, peroxidase and superoxide dismutase activities changed under Pb stress. The study indicated that increased activity of antioxidant enzymes may play as signal inducers to fight against Pb.