A bivalent histone mark reader, AtDEK2 governs plant immunity

In Arabidopsis thaliana , the nuclear protein DEK2 orchestrates diverse chromatin-related processes and exhibits phosphorylation in response to flagellin22 treatment, implicating its involvement in plant immunity against bacterial pathogens. Loss-of-function mutants of dek2 have their immunity compromised to both bacterial and fungal pathogens. Transcriptomic analysis of the dek2-1 mutant unveils AtDEK2 as a transcriptional repressor of defense-related genes, as well as genes associated with hormone synthesis and signaling. Chromatin immunoprecipitation sequencing (ChIP-Seq) analysis reveals that DEK2 binds to motifs of various transcription factor families, with a notable enrichment in class I TCP binding motif regions. Our findings indicate that DEK2 is recruited to specific chromatin regions by transcription factors and functions as a reader of the bivalent histone mark H3K4me3K27me3. Consequently, we propose a hypothetical working model wherein DEK2 acts as a transcriptional repressor targeting regions marked by H3K4me3K27me3, shedding light on its role in plant immunity.