OsNAC120 balances plant growth and drought tolerance by integrating GA and ABA signaling in rice

The crosstalk between gibberellin (GA) and abscisic acid (ABA) signaling is crucial for balancing plant growth and adaption to environmental stress. Nevertheless, the molecular mechanism of mutual antagonism still needs to be well understood. In this study, we find that knockout of rice NAC (NAM, ATAF1/2, CUC2) transcription factor gene OsNAC120 inhibits plant growth while enhances drought tolerance, but its overexpression lines act in an opposite way. Exogenous GA can rescue the semi-dwarf phenotype of osnac120 mutants, and further study shows that OsNAC120 promotes GA biosynthesis through transcriptionally activating GA biosynthetic genes OsGA20ox1 and OsGA20ox3. DELLA protein SLENDER RICE1 (SLR1) interacts with OsNAC120 and impedes its transactivation ability, while GA treatment can remove the inhibition of transactivation activity caused by SLR1. On the other hand, OsNAC120 negatively regulates rice drought tolerance by repressing ABA-induced stomatal closure. Mechanistic investigation illustrates that OsNAC120 inhibits ABA biosynthesis via transcriptional repression of ABA biosynthetic genes OsNCED3 and OsNCED4. Rice OSMOTIC STRESS/ABA-ACTIVATED PROTEIN KINASE 9 (OsSAPK9) physically interacts with OsNAC120 and mediates its phosphorylation, which results in OsNAC120 degradation. ABA treatment accelerates OsNAC120 degradation and reduces its transactivation activity. Together, our findings provide the evidence that OsNAC120 plays critical roles in balancing GA-mediated growth and ABA-induced drought tolerance in rice. The research will help us understand the mechanisms underlying the "trade-off" between plant growth and stress tolerance, and engineer stress-resistant and high-yielding crops.