Targeting eIF4A with RNA Aptamers Enhances Salt Stress Tolerance in Rice Through Modulation of Translation Initiation

Salt stress is a major limiting factor for rice productivity worldwide, and improving salt tolerance is crucial for ensuring sustainable agricultural production. In this study, we investigate the use of RNA aptamers to modulate eukaryotic initiation factor 4 A (eIF4A), a key regulator of translation initiation under stress conditions, to enhance salt stress tolerance in rice (Oryza sativa). Using Systematic Evolution of Ligands by EXponential enrichment (SELEX), we isolated high-affinity RNA aptamers that specifically bind to eIF4A. One aptamer, eApt-2, was found to bind eIF4A with high affinity, selectively blocking cap-dependent translation initiation. Radioisotope‑based helicase assays confirmed that eApt‑2 does not impair eIF4A's intrinsic RNA‑unwinding activity. Transfected rice expressing eApt-2 exhibited enhanced salt stress tolerance, with improved growth, biomass accumulation, and photosynthetic activity under saline conditions. Moreover, stable transgenic rice lines expressing eApt‑2 maintained enhanced growth and biomass accumulation under 150 mM NaCl stress, mirroring transient expression results, and transgenic Arabidopsis lines showed similar tolerance. Our results demonstrate the potential of RNA aptamers as a precise, reversible tool for enhancing stress resilience in crops, offering an alternative to conventional genetic modification methods. This study opens new avenues for engineering salt-tolerant rice and highlights the broader applicability of RNA aptamers in improving plant responses to abiotic stresses.