The ameliorative effect of H2 on aluminum (Al)-induced stress remains poorly understood. We treated maize seedlings with Al and hydrogen-rich water (HRW) to determine the roles of H2 in the alleviation of Al toxicity. Our results demonstrated that Al stress-triggered damage to the photosynthetic apparatus, plant growth inhibition, and reactive oxygen species (ROS) production, and boosted lipid peroxidation. However, the addition of HRW at 75% saturation markedly alleviated Al toxicity symptoms through the promotion of root elongation. These responses were related to the significantly increased activities of typical antioxidant enzymes (CAT, APX, SOD, and POD). In vivo imaging of plasma membrane integrity, lipid peroxidation, and the level of ROS provided further evidence that HRW could improve Al tolerance. Our results also indicate that 100% HRW mitigated Al toxicity less than 75% HRW. Moreover, different concentrations of HRW significantly improved photosynthesis and increased nutrient uptake. We conclude that exogenous H2 supplementation could enhance Al tolerance by reestablishing redox homeostasis and maintaining nutrient homeostasis.

Keywords: Al stress; Antioxidant enzymes; Hydrogen-rich water (HRW); Maize seedlings; Nutrient homeostasis.

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