CRISPR/Cas9-Mediated Knockout of OsbZIP76 Reveals Its Role in ABA-Associated Immune Signaling in Rice

The basic leucine zipper (bZIP) transcription factors are involved in a wide range of physiological processes in plants, including hormone signaling, stress responses, and growth and development regulation. They play a key role in abscisic acid (ABA)-mediated immune regulation. However, the immune-related function of OsbZIP76 in rice remains poorly understood. In this study, we generated OsbZIP76 knockout (KO) lines using CRISPR/Cas9-mediated genome editing and examined their phenotypic responses to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo) and the fungal pathogen Magnaporthe oryzae. The KO lines showed increased susceptibility to both pathogens compared to wild-type (WT) plants. Furthermore, qRT-PCR analysis revealed that, upon pathogen infection, the expression of pathogenesis-related genes such as PR1a, PR5, and NPR1 was significantly suppressed in the KO lines. ABA treatment experiments showed that KO lines were hypersensitive to exogenous ABA, indicating a role for OsbZIP76 in ABA perception and signaling. Notably, the expression of the OsbZIP76 gene itself was strongly induced by both ABA treatment and pathogen infection, supporting its role as a positive regulator in ABA-associated immune signaling. Overall, this study demonstrates that OsbZIP76 functions as an important immune regulator by integrating defense gene expression with ABA signaling, providing new insights into the molecular crosstalk between hormonal signaling and pathogen defense mechanisms.