OsGF14f, OsbZIP23, and OsFLZ20 form a hierarchical positive regulatory module that enhances drought tolerance in rice

Drought stress severely restricts global rice production, making the improvement of drought tolerance a central goal in rice breeding. Here, we identify rice FCS-like zinc finger protein 20 (OsFLZ20) as a previously unrecognized client of the 14-3-3 protein OsGF14f, a recently characterized and promising target for engineering of drought-tolerant rice cultivars. OsFLZ20 transcription is rapidly and robustly induced by drought, and transgenic analyses show that OsFLZ20 enhances drought tolerance by increasing soluble sugar accumulation and alleviating oxidative damage, without affecting normal growth or yield. OsGF14f and OsFLZ20 co-regulate a broad suite of drought-responsive genes, with OsGF14f enhancing OsFLZ20-driven transcriptional reprogramming. Mechanistically, OsGF14f interacts with OsFLZ20 at Ser-64 and increases its protein abundance. In parallel, the OsGF14f-OsbZIP23 module enhances the transcriptional activation of OsFLZ20 under drought. Further genetic analyses reveal that the full function of OsFLZ20 in drought tolerance requires a functional OsGF14f, and loss of OsFLZ20 compromises the drought tolerance conferred by OsGF14f, demonstrating the mutual interdependence of these two regulators within the drought-response network. Collectively, these findings establish the OsGF14f-OsbZIP23-OsFLZ20 module as a previously unrecognized determinant of rice drought tolerance, providing molecular insights and promising genetic targets for crop improvement.