Characterization of OsCAF1 Protein Function in Rice Response to Thermal Stress

Heat stress is a critical environmental challenge that disrupts rice growth, development, and productivity and poses a significant threat to global food security. The CCR4-NOT protein complex, particularly its CCR4-associated factor 1 (CAF1) subunit, plays a crucial role in the dynamic regulation of gene expression by mediating mRNA de-adenylation, a key step in mRNA degradation and turnover. However, the specific function of OsCAF1 proteins under heat stress in rice remains poorly understood. In this study, we investigated the dynamic subcellular localization of OsCAF1A in response to elevated temperatures and its role in heat stress tolerance. Under normal conditions, OsCAF1A is diffusely localized to the cytoplasm. However, OsCAF1A predominantly localizes to processing bodies (PBs) under heat stress. The results of interaction studies revealed that two DEAD-box RNA helicases, OseIF4AIIb and OsRH8, modulate the re-localization of OsCAF1A, by OseIF4AIIb inhibiting and OsRH8 promoting its association with PBs during heat stress. Furthermore, OsCAF1A mRNA was more abundantly expressed in rice seedlings than other OsCAF1 genes and is further upregulated by high temperature. The overexpression of OsCAF1A significantly enhanced heat tolerance, whereas mutants exhibited increased heat sensitivity. These findings underscore the potential of OsCAF1A as a tool to improve crop resilience to climate change.