ONAC122 and ONAC131, controlled by OsSRWD1, OsRACK1A, and OsRGLG2, regulate rice immunity through modulating...

The NAM, ATAF1/2, and CUC2 (NAC) transcription factors play critical roles in plant immunity by modulating the expression of target genes. ONAC122 and ONAC131 have been shown to positively regulate rice blast resistance through gene silencing approach; however, the underlying mechanism remains unexplored. Here, we investigated the regulatory mechanisms of ONAC122 and ONAC131 in rice immunity by characterizing their target genes and interacting partners. We confirmed the positive roles of ONAC122 and ONAC131 in rice immunity through both overexpression and knockout lines and revealed their regulation of immune-associated genes. ONAC122 binds to the canonical CACG cis-element and the newly identified ACTC cis-element, while ONAC131 only binds to the CACG cis-element. ONAC122 activates the transcription of OsRFPH2-2 and OsBIERF3, two positive regulators of rice immunity, through directly binding to the CACG cis-element, while ONAC131 synergistically enhances the ONAC122-triggered transcriptional activation. OsSRWD1 and OsRACK1A enhance the transcriptional activity of ONAC122, whereas OsRGLG2 impairs it. OsRGLG2, a negative regulator of blast resistance, acts upstream of ONAC122 and ubiquitinates ONAC122 and ONAC131 for degradation. These findings establish a regulatory module in which ONAC122 and ONAC131, controlled by OsRGLG2, OsSRWD1, and OsRACK1A, positively regulate rice immunity by activating the transcription of OsRFPH2-2 and OsBIERF3.