OsHDAC1 Deacetylates and Stabilizes Heat‐Induced OsHSA32 to Enhance Thermotolerance in Rice

Unseasonal high temperatures caused by global warming adversely impact crop growth and yield. Post-translational modifications (PTMs) of proteins play critical roles in plant responses to environmental stresses. However, the PTM-based regulatory mechanisms of heat stress proteins remain poorly understood. In this study, we report that the histone deacetylase OsHDAC1 overexpression in rice enhances heat tolerance, whereas OsHDAC1 RNA interference (RNAi) lines exhibit increased heat sensitivity. OsHDAC1 physically interacts with OsHSA32, a plant-specific atypical heat-induced protein, while oshsa32 knockout mutants display reduced tolerance to heat. Mechanistically, OsHDAC1 stabilizes OsHSA32 via deacetylation, thereby promoting the heat tolerance of rice. Further analysis reveals that OsHDAC1-mediated deacetylation inhibits the interaction between OsHSA32 and the RING-type E3 ubiquitin ligase OsRFPH2-11, thereby preventing ubiquitin-proteasome-mediated degradation of OsHSA32. Collectively, our findings uncover a PTM-based regulatory mechanism by which deacetylation modulates the stability of a heat-induced protein to enhance thermotolerance in rice.