Green-synthesized Fe–Zn bimetallic nanoparticles alleviated cadmium accumulation and enhanced plant growth in Oryza sativa L. cv. (IR64)

Abstract

Cadmium (Cd) contamination in rice causes severe health hazards and compromises food safety; therefore, it is crucial to minimise Cd toxicity. In the present study, a novel green-synthesized Fe–Zn bimetallic nanoparticle (Fe–Zn BNP) was evaluated for Cd remediation and growth-promoting potential. Fourteen day-old indica rice seedlings were co-treated with 10 μM CdCl₂ and Fe–Zn BNPs (25 mg L⁻¹) for seven days and assessed for growth, stress parameters, and Cd content. Results indicated that Fe–Zn BNPs could effectively restore impaired growth parameters (root, shoot length, fresh and dry weight) and elevate chlorophyll and its precursor molecules (δ-ALA and PBG), eventually increasing photosynthetic efficiency by 72.21%. Significant reduction of ROS formation and other stress markers (MDA, methylglyoxal) were also observed. This study revealed a significant increase in Fe and Zn content upon treatment of Cd-stressed seedlings with Fe–Zn BNPs. Fe–Zn BNPs were found to restrict Cd localisation in root apices and reduce translocation from the root to the shoot by phytochelatin-mediated Cd sequestration (32.38% in the shoot and 42.39% in the root). Simultaneously, Fe–Zn BNPs downregulated the expression of Fe and Zn transporter genes OsIRT1, OsZIP1, and OsZIP4. Therefore, this research offers a promising avenue for the efficient amelioration of Cd toxicity in rice and improved plant health by developing a novel BNP.