Modulation of jasmonate signaling in rice (Oryza sativa L.) under abiotic stress: functional divergence of OsJAZ12 and OsJAZ13 in stress and hormone responses

Jasmonate (JA) is a key phytohormone regulating plant growth and stress responses, yet its role in rice abiotic stress tolerance remains poorly understood. In this study, we investigated the functional roles of two JA signaling components, OsJAZ12 and OsJAZ13, in rice stress responses. Using yeast two-hybrid assays, we demonstrated that OsJAZ12 interacts with OsCOI1b in a coronatine (COR)-dependent manner, while OsJAZ13 does not. Both OsJAZ12 and OsJAZ13 interact with OsNINJA, suggesting their involvement in a JAZ-NINJA-TPL transcriptional repressor complex. OsJAZ12 exhibited stronger and earlier upregulation than OsJAZ13 under NaCl, PEG, abscisic acid (ABA) and methyl jasmonate (MeJA) treatments. CRISPR/Cas9-generated knockout mutants of OsJAZ12, OsJAZ13, OsCOI1b, and OsNINJA were used to explore their roles under abiotic stress and hormone treatments. Phenotypic analysis revealed that Osjaz12 and Oscoi1b mutants exhibited significantly inhibited root growth under NaCl stress, while Osjaz13 showed enhanced growth under osmotic stress. Furthermore, Osjaz12 and Oscoi1b were more sensitive to exogenous ABA, whereas Osjaz13 and Osninja were more sensitive to MeJA. Quantitative real-time PCR (qRT-PCR) analysis indicated that JA signaling regulates key stress-responsive genes, including OsDREB2A, OsLEA3, OsNAC2, and DST. Knockout of OsJAZ12, OsJAZ13, and OsNINJA inhibited ABA synthesis gene expression, while knockout of Oscoi1b enhanced ABA degradation gene OsABA8ox1. These findings highlight the functional divergence of OsJAZ12 and OsJAZ13 in JA and ABA signaling pathways, with OsJAZ12 primarily modulating ABA-dependent responses and OsJAZ13 influencing JA-related stress responses. This study provides new insights into the regulatory mechanisms of JA signaling in rice abiotic stress tolerance and offers potential targets for improving stress resilience in rice.