Pretreatment with H2O2 Alleviates Aluminum-induced Oxidative Stress in Wheat Seedlings

Hydrogen peroxide (H2O2) is a key reactive oxygen species (ROS) in signal transduction pathways leading to activation of plant defenses against biotic and abiotic stresses. In this study, we investigated the effects of H2O2 pretreatment on aluminum (Al) induced antioxidant responses in root tips of two wheat (Triticum aestivum L.) genotypes, Yangmai-5 (Al-sensitive) and Jian-864 (Al-tolerant). Al increased accumulation of H2O2 and O-2 center dot- leading to more predominant lipid peroxidation, programmed cell death and root elongation inhibition in Yangmai-5 than in Jian-864. However, H2O2 pretreatment alleviated Al-induced deleterious effects in both genotypes. Under Al stress, H2O2 pretreatment increased the activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and monodehydroascorbate reductase, glutathione reductase and glutathione peroxidase as well as the levels of ascorbate and glutathione more significantly in Yangmai-5 than in Jian-864. Furthermore, H2O2 pretreatment also increased the total antioxidant capacity evaluated as the 2, 2-diphenyl-1-picrylhydrazyl-radical scavenging activity and the ferric reducing/antioxidant power more significantly in Yangmai-5 than in Jian-864. Therefore, we conclude that H2O2 pretreatment improves wheat Al acclimation during subsequent Al exposure by enhancing the antioxidant defense capacity, which prevents ROS accumulation, and that the enhancement is greater in the Al-sensitive genotype than in the Al-tolerant genotype.