Histone methylation is involved in a wide range of biological regulation in plants, and is conducted by three major components, including methyltransferases, demethylases, and histone readers. Compared with the other two components, research on histone readers is relatively limited. In this study, we demonstrate that OsSHH5 functions as an H3K9me1 reader to regulate rice disease resistance, tillering, and grain yield. Loss of OsSHH5 function significantly enhances both grain yield and disease resistance. Mechanistically, OsSHH5 recruits the H3K9 methyltransferase SGD733 and binds to H3K9me1, thereby maintaining H3K9me1 enrichment and facilitating gene silencing. In leaves, OsSHH5 interacts with the transcriptio... More
Histone methylation is involved in a wide range of biological regulation in plants, and is conducted by three major components, including methyltransferases, demethylases, and histone readers. Compared with the other two components, research on histone readers is relatively limited. In this study, we demonstrate that OsSHH5 functions as an H3K9me1 reader to regulate rice disease resistance, tillering, and grain yield. Loss of OsSHH5 function significantly enhances both grain yield and disease resistance. Mechanistically, OsSHH5 recruits the H3K9 methyltransferase SGD733 and binds to H3K9me1, thereby maintaining H3K9me1 enrichment and facilitating gene silencing. In leaves, OsSHH5 interacts with the transcriptional factor HPY1 to target the resistance-related genes OsWAKg52 and OsWRKY81, maintaining their H3K9me1 levels and suppressing multiple PAMP-triggered immune responses, which ultimately reduces rice disease resistance. In tiller buds, OsSHH5 interacts with the transcriptional factor TCP19 to target the tillering-related gene OsNGR5, maintaining its H3K9me1 enrichment and inhibition of tillering, leading to reduced yield. Collectively, these findings reveal that OsSHH5 plays a vital role in integrating immune response, tillering, and grain yield in rice, providing new insights into the function of histone readers and offering a new strategy to improve rice yield and disease resistance.
