Epigenetic Control of a Multifunctional Stress Regulator. Epigenetic Control of a Multifunctional Stress Regulator

Here we report the identification of ETHYLENE-INSENSITIVE6 (EIN6), which is a H3K27me3 demethylase also known as RELATIVE OF EARLY FLOWERING6 (REF6), and EIN6 ENHANCER (EEN), the Arabidopsis homolog of the yeast INO80 chromatin remodeling complex subunit IES6 (INO EIGHTY SUBUNIT6). By applying high-throughput profiling of histone modifications, histone variant occupancy, cytosine methylation and mRNA expression in various Arabidopsis mutants, we identified ETHYLENE-INSENSITIVE2 (EIN2) as a direct target of EIN6 (REF6) and EEN. EIN6 (REF6) and EEN as part of the INO80 complex interdependently and uniquely control the level and the localization of the repressive histone modification H3K27me3 and the histone variant H2A.Z at the 5’ untranslated region (5’UTR) intron of EIN2. Concomitant functional loss of EIN6 (REF6) and the INO80 complex shifts the chromatin landscape at EIN2 to a repressive state causing a dramatic reduction of EIN2 expression and subsequent collapse of the entire ethylene transcriptional cascade. Overall design: ChIP-seq, ChIP-reChIP-seq, MethylC-seq and RNA-seq was applied to comprehensively profile the chromatin landscape in various Arabidopsis mutants and different tissue types.