Synergistic ameliorative effect of iron oxide nanoparticles andBacillus subtilisS4 against arsenic toxicity inCucurbita moschata: polyamines, antioxidants, and physiochemical studies

The present study was intended to assess the potential of iron oxide nanoparticles (IONPs) andBacillus subtilisS4 in mitigation of arsenic (As) stress inCucurbita moschata.Cucurbita moschataseedlings were subjected to As stress for 60 days. Reduced level of growth parameters including photosynthetic pigments, rate of photosynthesis and gas exchange characteristics was observed in seedlings subjected to As stress. However, IONPs andB. subtilisS4 improved growth attributes and proline contents in supplementedC. moschataseedlings.Bacillus subtilisS4 inoculated seedlings showed higher activity of peroxidase (POD) and superoxide dismutase (SOD) under As toxicity. Similarly, the co-application of IONPs andB. subtilisS4 further increased the activity of these antioxidative enzymes. The As stress alleviation in inoculatedC. moschataseedlings is credited to reduced levels of hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) in IONPs andB. subtilisS4-treated plants. Furthermore, synergism between plant growth promoting bacteria (PGPB) and IONPs enhanced the biosynthesis of stress mitigating polyamines including spermidine and putrescine in As-stressed seedlings. Current research reveals that synergistic application of IONPs andB. subtilisS4 is an effective sustainable and ecofriendly approach for alleviation of As stress inC. moschataseedlings.