Abstract
Summary
Drought tolerance in plants requires rapid conversion of water‐deficit signals into protective transcriptional and epigenetic programs. Although ERF transcription factors (TFs) are central regulators of stress‐responsive gene expression, how drought‐induced kinase signaling is coupled to chromatin regulation and antioxidant gene activation remains unclear.
Here, we identify the ERF TF BpERF3 as a phosphorylation‐dependent regulator of drought tolerance in birch (
Betula platyphylla
). Using transgenic and CRISPR‐Cas9 mutant lines, protein interaction assays, immunoaffinity fluorescent electrophoresis (IAFE)‐based interactome mapping, post‐translational modification analysis, reactive oxygen species measurements, and drought phenotyping, we dissected the regulatory mechanism underlying BpERF3‐mediated stress adaptation.
We show that BpERF3 activates the peroxidase (
POD
) genes
BpPOD3
and
BpPOD4
, which are required for its drought‐protective function. Mechanistically, BpSRK1 phosphorylates BpERF3 at Ser355, enabling phosphorylated BpERF3 to competitively engage the HDAC domain of BpHDA6 and restrict BpHDA6‐dependent histone H3.1 deacetylation. Consequently, H3.1 acetylation is maintained, chromatin relaxes, downstream stress‐responsive genes are activated, and drought tolerance is enhanced in birch.
Our findings reveal a BpSRK1‐BpERF3‐BpHDA6‐H3.1 regulatory module that links drought‐induced phosphorylation to local chromatin activation and redox homeostasis, providing mechanistic insight into plant stress adaptation.