Metal‐Tolerant Rhizobacteria Alleviate Aluminum Toxicity in Maize Via Biosorption, Antioxidant Activation, and ROS Reduction

ABSTRACT Aluminum (Al) is a major environmental pollutant that disrupts plant metabolism, inhibits growth, and reduces crop productivity. Beneficial metal‐tolerant rhizobacteria can help plants mitigate Al stress. This study evaluated the potential of metal‐tolerant rhizobacteria to enhance Al tolerance in maize ( Zea mays L.). Pseudomonas azotoformans PSZ‐1 (Accession no. PV605389.1) and Achromobacter sp. PSZ‐5 (Accession no. PV639388.1) tolerated 120 and 100 μM Al, respectively, produced PGP substances, and effectively biosorbed Al 3+ ions. Aluminum, particularly at 80 μM, had phytotoxic effects on maize, reducing growth and photosynthetic traits while elevating ROS, oxidative stress, and metal uptake. Inoculation with PSZ‐1 and PSZ‐5 alleviated Al‐induced toxicity, enhancing maize performance under metal stress. Both strains significantly ( p ≤ 0.05) improved root biomass (30.7%, 35.7%), carotenoids (23.4%, 29.8%), chlorophyll fluorescence (27.2%, 29.4%), photosynthetic rate (24.8%, 33%), and stomatal conductance (29.7%, 35.4%) in 20 μM Al 3+ ‐stressed maize over uninoculated controls. ROS (H 2 O 2 , superoxide) and oxidative stress markers (EL, MDA) were significantly reduced ( p ≤ 0.001) in bacterial‐primed maize. Bacterial inoculation reduced Al accumulation in roots and shoot tissues of maize. At 40 μM Al, PSZ‐5 significantly upregulated the activities of APX, CT, and POD by 30.1%, 26.8%, and 22.6%, while PSZ‐1 maximally enhanced SOD and GR by 37.8% and 25.6% in roots, respectively. Multivariate analyses confirmed the strong parameter associations among treatments. Overall, applied PGPR strains showed promise for bioremediation of Al‐contaminated soils and improving maize growth and tolerance. Future work should validate their performance under field conditions and explore molecular mechanisms and microbial consortia development.