Histone H3 lysine 4 trimethylation-regulated GRF11 expression is essential for the iron deficiency response in Arabidopsis thaliana.

A mutant, non-response to Fe-deficiency2 (nrf2) with defects on the response to iron (Fe) deficiency, was selected by a designed genetic screening. The corresponding gene NRF2 encodes a tetratricopeptide repeat (TPR) domain-containing protein and was previously recognized as EARLY FLOWERING8 (ELF8) involved in the regulation of flowering time. NRF2/ELF8 plays a role in regulating the expression of a floral transition repressor FLC in the shoot through trimethylation of histone H3 lysine4 (H3K4me3). This study further elucidated its role in Fe homeostasis by targeting a 14-3-3 regulator GRF11 involved in Fe deficiency response in the root through H3K4me3. The expression of GRF11 is compromised in the nrf2/elf8 mutant because of the reduction of H3K4me3 in the enhancer region. This work sheds light on a missing piece in epigenetic control of gene expression by H3K4me3 in the Fe deficiency response to regulate Fe acquisition.