Histone H3 lysine4 trimethylation‐regulated GRF11 expression is essential for the iron‐deficiency response in Arabidopsis thaliana

Summary Iron (Fe) homeostasis in plants is controlled by both transcription factors (TFs) and chromatin remodeling through histone modification. To date, few studies have reported the existence of histone modification in maintaining the Fe‐deficiency response. However, the reports that do exist shed light on various histone modifications, but knowledge of the activation mark in Fe‐deficiency response is lacking. By using a forward genetics approach, we identified a crucial allele for Fe‐deficiency response, NON‐RESPONSE TO Fe‐DEFICIENCY2 (NRF2), previously described as EARLY FLOWERING8 (ELF8) associated with an activation mark on histone modification, histone H3 lysine4 trimethylation. In the nrf2‐1 mutant, a point mutation at ELF8T404I, exhibits impaired expression of GENERAL REGULATORY FACTOR11 (GRF11) and downstream genes in the Fe‐uptake pathway. In vivo chromatin immunoprecipitation revealed that in roots, NRF2/ELF8 is essential for the expression of GRF11 for Fe‐deficiency response, whereas in shoots, NRF2/ELF8 regulates FLOWERING LOCUS C (FLC) expression for flowering time control. In summary, a key factor, NRF2/ELF8, involved in epigenetic regulation essential for both flowering time control and Fe‐deficiency response is uncovered.