<p>In the current industrial scenario, chromium (Cr) and lead (Pb) contamination poses a serious threat to agricultural ecosystems due to their toxic effects on plant growth and productivity. However, limited studies have explored the role of plant growth-promoting rhizobacteria (PGPR) in alleviating combined Cr and Pb stress in rice. Therefore, the present study investigated the potential of <i>Pseudomonas putida</i>, <i>Bacillus amyloliquefaciens</i>, and <i>Pseudomonas fluorescens</i> in mitigating metal-induced toxicity in rice (<i>Oryza sativa</i> L.) under different Cr and Pb levels [0 (without Cr and Pb stress), 100 and 200&#xa0;mg kg⁻<sup>1</sup>)]. The research outcomes indicated that elevated levels of Cr and Pb stress in the soil significantly (<i>P</i> ≤ 0.05) decreased plant growth, biomass, photosynthetic pigments, and gas exchange characteristics, while increasing oxidative stress biomarkers including malondialdehyde (MDA) and hydrogen peroxide (H₂O₂). Metal toxicity also altered antioxidant defense systems, sugar accumulation, proline metabolism, and the ascorbate–glutathione (AsA–GSH) cycle. However, the application of <i>P. putida</i>, <i>B. amyloliquefaciens</i>, and <i>P. fluorescens</i> significantly improved morphophysiological and biochemical attributes, enhanced antioxidant defense and related gene expression, reduced oxidative damage, and decreased Cr and Pb accumulation in plant tissues. Furthermore, PGPR application improved cellular fractionation and regulated stress-responsive metabolic pathways in <i>O. sativa</i> under metal-stressed conditions. Overall, the findings highlight the significant potential of these PGPR strains as sustainable biological agents for improving metal stress tolerance and physiological performance in <i>O. sativa</i> plants grown under Cr and Pb toxicity.</p>

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Plant growth-promoting rhizobacteria enhance metal tolerance in rice (Oryza sativa L.) under chromium and lead stress

  • Rana M. Alshegaihi,
  • Muna Abdul-Rahman Al-Malki,
  • Dalia Mohammad Melebari,
  • Hanan El Sayed Osman,
  • Dikhnah Alshehri,
  • Suliman Mohammed Suliman Alghanem,
  • Khalid Ali Khan,
  • Amany H. A. Abeed,
  • Sharifullah Sharifi

摘要

In the current industrial scenario, chromium (Cr) and lead (Pb) contamination poses a serious threat to agricultural ecosystems due to their toxic effects on plant growth and productivity. However, limited studies have explored the role of plant growth-promoting rhizobacteria (PGPR) in alleviating combined Cr and Pb stress in rice. Therefore, the present study investigated the potential of Pseudomonas putida, Bacillus amyloliquefaciens, and Pseudomonas fluorescens in mitigating metal-induced toxicity in rice (Oryza sativa L.) under different Cr and Pb levels [0 (without Cr and Pb stress), 100 and 200 mg kg⁻1)]. The research outcomes indicated that elevated levels of Cr and Pb stress in the soil significantly (P ≤ 0.05) decreased plant growth, biomass, photosynthetic pigments, and gas exchange characteristics, while increasing oxidative stress biomarkers including malondialdehyde (MDA) and hydrogen peroxide (H₂O₂). Metal toxicity also altered antioxidant defense systems, sugar accumulation, proline metabolism, and the ascorbate–glutathione (AsA–GSH) cycle. However, the application of P. putida, B. amyloliquefaciens, and P. fluorescens significantly improved morphophysiological and biochemical attributes, enhanced antioxidant defense and related gene expression, reduced oxidative damage, and decreased Cr and Pb accumulation in plant tissues. Furthermore, PGPR application improved cellular fractionation and regulated stress-responsive metabolic pathways in O. sativa under metal-stressed conditions. Overall, the findings highlight the significant potential of these PGPR strains as sustainable biological agents for improving metal stress tolerance and physiological performance in O. sativa plants grown under Cr and Pb toxicity.