OsFKBP20‐1b stabilizes OsUPF1 and OsUPF2 to promote the degradation of aberrant mRNAs during dehydration stress

ABSTRACT The selective degradation of aberrant mRNAs plays a vital role in ensuring cellular survival under stress conditions. Here, we investigated the role of OsFKBP20‐1b, a splicing factor, in dehydration stress response in rice ( Oryza sativa ). We show that OsFKBP20‐1b associates with the core nonsense‐mediated mRNA decay (NMD) components, UP‐FRAMESHIFT1 (OsUPF1) and OsUPF2, enhances their stability, thereby supporting the efficient degradation of aberrant transcripts during dehydration stress. These associations were demonstrated using bimolecular fluorescence complementation (BiFC), co‐immunoprecipitation (Co‐IP), and in vitro binding assays. Integrative analyses combining ribosome profiling and transcriptome sequencing further revealed that OsFKBP20‐1b influences both alternative splicing (AS) patterns and translational dynamics of stress‐responsive transcripts. Notably, loss of OsFKBP20‐1b compromises OsUPF1‐ and OsUPF2‐mediated decay of aberrant mRNAs under dehydration conditions. Consistent with these molecular defects, osfkbp20‐1b mutant plants exhibited heightened sensitivity to dehydration stress. Together, our findings identify OsFKBP20‐1b as a key regulator linking pre‐mRNA splicing with cytoplasmic RNA surveillance during dehydration stress, thereby providing mechanistic insight into post‐transcriptional control of stress adaptation in rice. These results advance our understanding of RNA quality control pathways in plants and suggest potential molecular targets for improving drought‐resilience in crops.