Drought represents one of the most devastating abiotic stresses to global agriculture, severely constraining productivity of staple crops worldwide.
Developing drought-resilient cultivars is therefore critical for food security, necessitating both identification of key genetic regulators and elucidation of complex drought signaling mechanisms.
Here, researchers identified Drought Tolerance 5 (OsDT5), a bHLH transcription factor that functions as a negative regulator of drought tolerance throughout the rice growth cycle. They demonstrate that Osmotic Stress/ABA-Activated Protein Kinase 9 (SAPK9)-mediated phosphorylation at Ser27/Ser136 residues modulates OsDT5 activity through accelerating its proteasomal degradation, disrupting its interaction with OsbZIP66, and reducing its binding affinity for OsLEAs promoters.
Strikingly, knockout of OsDT5 orthologs recapitulated the drought-resilient phenotype not only in cereals (maize and wheat), but also in the bryophyte Physcomitrium patens. Crucially, molecular validation and AlphaFold3-predicted structural orthology confirmed evolutionary preservation of the entire SAPK9-DT5-bZIP66 module architecture.
Collectively, their findings deliver a unified mechanistic framework for drought adaptation in terrestrial plants and actionable breeding strategies for climate-resilient agriculture in drought-challenged ecosystems.
