LncRNA MtCIR2 Negatively Regulates Response of Medicago truncatula Seedlings to Salt Stress by Targeting SOS2-Dependent Na Efflux via H2A Ubiquitination.

LncRNA MtCIR2 epigenetically suppresses SOS2-dependent Na efflux, reducing salt stress tolerance in Medicago truncatula seedlings by promoting H2A ubiquitination at MtSOS2.

• Why it matters: Understanding how lncRNAs regulate plant responses to salt stress is crucial for developing crops with improved stress resilience, yet the epigenetic mechanisms remain poorly understood.
• What they did: The study used over-expression and mutant lines of MtCIR2, along with ChIP assays, to demonstrate that MtCIR2 interacts with BMI1 and promotes H2A ubiquitination at MtSOS2, repressing its expression and Na exclusion.
• The result: This reveals a novel epigenetic pathway where MtCIR2 modulates Na accumulation and salt sensitivity, providing insights into plant stress regulation and potential targets for crop improvement.