The OsNAC3-OsITPK4-OsMT2b module regulates rice seed germination through the reactive oxygen species pathway

Seed germination is a critical agronomic trait for direct-seeding cultivation in rice. While maintaining reactive oxygen species (ROS) homeostasis is essential for this process, the underlying molecular mechanisms remain largely unknown. Here, we reveal that the OsNAC3-OsITPK4-OsMT2b module regulates seed germination by modulating ROS homeostasis. In this module, OsITPK4, a member of the inositol 1,3,4-triphosphate 5/6-kinase family, is specifically induced during seed germination and functions as a positive regulator. Mechanistically, OsITPK4 interacts with and enhances the stability of metallothionein 2b (OsMT2b), a known ROS scavenger that acts downstream to facilitate seed germination. Furthermore, OsITPK4 expression is transcriptionally activated by the NAC transcription factor OsNAC3, which binds directly to its promoter and acts upstream to contribute to seed germination. The OsNAC3-OsITPK4-OsMT2b signaling cascade promotes seed germination by preventing ROS overaccumulation. Collectively, our findings provide valuable insights for breeding rice varieties with improved cultivation adaptability.