Differential gene expressions of rice superoxide dismutase isoforms to oxidative and environmental stresses

Active oxygen species (AOSs) are produced under stress conditions of plant cells. Superoxide dismutase (SOD) catalyzes the first step in the AOS scave nging system. The responses of SOD genes to environmental stresses were ana lyzed in rice seedlings by the treatments of drought, salinity and chilling . The expressions of abscisic acid (ABA)-inducible genes, Mn-SOD gene (sodA 1) and one of the cytosolic Cu/Zn-SOD genes (sodCc2), were strongly induced by the treatment of drought and salinity. While Fe-SOD gene (sodB) and the other cytosolic Cu/Zn-SOD gene (sodCc1) were also induced by ABA. However the mRNA level of sodB was decreased by drought treatment, and sodCc1 gene was not induced by drought and salinity treatments. Plastidic Cu/Zn-SOD gen e (sodCp) quickly responded to salinity treatment in the light but not in t he dark. In the treatment with hydrogen peroxide, sodCp gene was strongly i nduced shortly after the treatment. These results suggested that phytohormo ne and AOSs are associated with the regulation of SOD genes under environme ntal stresses.