Magnesium decreases aluminum accumulation and plays a role in protecting maize from aluminum-induced oxidative stress

Background: Acidic soils with a pH_water below 5.5 occupy up to 40% of world’s arable land. Aluminum (Al) toxicity and magnesium (Mg) deficiency often coexist in acidic soils, limiting crop production. In this study, we investigated a role of Mg in alleviation of Al stress in maize (Zea mays) by characterizing the growth responses, Al accumulation and the antioxidant properties of plants cultured hydroponically. Methods: Physiological and molecular analyses were used to investigate the mechanisms of Mg governing the alleviation of Al-induced ROS production and root growth inhibition. Results: Aluminum (50 μM) decreased root growth and induced oxidative stress. Exogenously added millimolar concentrations of Mg significantly alleviated Al toxicity as evidenced by restoration of plant growth, suppression of Al uptake, and a decline in root H₂O₂ concentration. Furthermore, the addition of Mg to the Al treatment solution enhanced the activities and expression of genes encoding superoxide dismutase, catalase and peroxidase compared to the Al-only treatment. Conclusions: The results indicate that Mg plays a role in alleviation of Al toxicity, reduction of Al accumulation and protection from Al-induced oxidative stress through activation of antioxidative enzymes.