Sulfur dioxide promotes seed germination by modulating reactive oxygen species production in maize.

Sulfur dioxide (SO2) is generally considered to be toxic to cells, but recent studies have shown that SO2 has positive roles in stress defense responses in plants. However, whether SO2 functions as a signaling molecule in the developmental process, especially in seed germination, is yet to be studied. Here, we present data supporting the role of SO2 in seed germination and possible molecular mechanisms. SO2 treatment significantly promoted the seed germination and seed vigor in maize. The germinating seeds treated with SO2 treatment exhibited higher reactive oxygen species (ROS) levels and NADPH oxidase activities. Furthermore, the specific NADPH oxidase inhibitor diphenyleneiodinium (DPI) strongly inhibited ROS accumulations, and SO2-promoted seed germination and vigor. Meanwhile, α-Amylase activity and transcripts in germinating seeds treated with SO2 were significantly elevated. These data have demonstrated that NADPH oxidase-dependent ROS production contributes to the induction of α-Amylase activity, thereby promoting seed germination upon SO2 exposure. SO2 might function as a signaling molecule in plant growth and development, especially in seed germination. This study might provide a theoretical foundation for the potential exploitation of hydrated SO2 in seed germination control in crop management.