Overexpression of the Maize Sulfite Oxidase Increases Sulfate and GSH Levels and Enhances Drought Tolerance in Transgenic Tobacco.

Sulfite oxidase (SO) plays a pivotal role in sulfite metabolism. In our previous study, sulfite-oxidizing function of the from () was characterized. To date, the knowledge of involvement in abiotic stress response is scarce. In this study, we aimed to investigate the role of in drought stress. The transcript levels of were relatively high in leaves and immature embryos of maize plants, and were up-regulated markedly by PEG-induced water stress. Overexpression of improved drought tolerance in tobacco. -overexpressing transgenic plants showed higher sulfate and glutathione (GSH) levels but lower hydrogen peroxide (HO) and malondialdehyde (MDA) contents under drought stress, indicating that confers drought tolerance by enhancing GSH-dependent antioxidant system that scavenged ROS and reduced membrane injury. In addition, the transgenic plants exhibited more increased stomatal response than the wild-type (WT) to water deficit. Interestingly, application of exogenous GSH effectively alleviated growth inhibition in both WT and transgenic plants under drought conditions. qPCR analysis revealed that the expression of several sulfur metabolism-related genes was significantly elevated in the -overexpressing lines. Taken together, these results imply that confers enhanced drought tolerance in transgenic tobacco plants possibly through affecting stomatal regulation, GSH-dependent antioxidant system, and sulfur metabolism-related gene expression. could be exploited for developing drought-tolerant maize varieties in molecular breeding.