<i>Arabidopsis</i> JMJ17 promotes cotyledon greening during de‐etiolation by repressing genes involved in tetrapyrrole biosynthesis in etiolated seedlings

Arabidopsis histone H3 lysine 4 (H3K4) demethylases play crucial roles in several developmental processes, but their involvement seedling establishment remain unexplored. Here, we show that JUMONJI DOMAIN-CONTAINING PROTEIN17 (JMJ17), an H3K4me3 demethylase, is involved cotyledon greening during establishment. Dark-grown seedlings of jmj17 accumulated a high concentration protochlorophyllide, intermediate metabolite the tetrapyrrole biosynthesis (TPB) pathway generates chlorophyll (Chl) photomorphogenesis. Upon light irradiation, mutants displayed decreased and reduced Chl level compared with wild-type; overexpression JMJ17 completely rescued jmj17-5 phenotype. Transcriptomics analysis uncovered genes encoding key enzymes TPB were upregulated etiolated seedlings. Consistently, chromatin immunoprecipitation-quantitative PCR revealed elevated at promoters target genes. Chromatin association was diminished upon exposure. Furthermore, interacted PHYTOCHROME INTERACTING FACTOR1 yeast two-hybrid assay. binds directly to gene demethylate suppress PROTOCHLOROPHYLLIDE OXIDOREDUCTASE C expression dark. Light results de-repression modulate de-etiolation. Our study reveals new role for demethylase controlling dark-to-light transition.