OsGRP3 deacetylation drives nuclear condensate assembly and transcriptional reprogramming under salt stress

High soil salinity poses a major threat to global crop yields. Although cytoplasmic stress granules are known to contribute to plant responses to salt stress, the function and regulatory mechanisms of nuclear condensates in rice during stress response have remained elusive. Here, we demonstrate that the RNA-binding protein OsGRP3 assembles into nuclear condensates in response to salt stress. OsGRP3 undergoes deacetylation, which promotes its liquid-liquid phase separation (LLPS) and the formation of nuclear condensates. These condensates specifically recruit the OsZHD1.1 splice variant of the transcription factor OsZHD1, but not OsZHD1.2. Mechanistically, OsGRP3 enhances the transcriptional activity of OsZHD1.1, leading to the upregulation of key salt stress-responsive genes, including OsHKT1;4 and OsSOS1, ultimately limiting shoot sodium accumulation and enhancing root sodium extrusion. Our findings identify deacetylation-driven OsGRP3 condensation as a mechanism that promotes OsZHD1.1 recruitment and transcriptional activation of salt-responsive genes, thereby contributing to Na+ homeostasis and salt tolerance in rice. This study provides a mechanistic framework for understanding how stress-responsive nuclear condensates coordinate transcriptional reprogramming in plants.