Epigenetic silencing of a multifunctional plant stress regulator.

Mark Zander,Robert Mcgrath,Yupeng He,Joanne Chory,Florian Jupe,Björn C Willige,Anna Stepanova,Joseph R Ecker,Elizabeth Howell,Zhuzhu Zhang,Joseph R Nery,Anna Bartlett,Huaming Chen,Robert J Schmitz,Amber E Langford,Mathew G Lewsey,Ramlah Nehring,Rosa Castanon,Thu A Nguyen

doi:10.7554/elife.47835

Abstract

The central regulator of the ethylene (ET) signaling pathway, which controls a plethora of developmental programs and responses to environmental cues in plants, is ETHYLENE-INSENSITIVE2 (EIN2). Here we identify a chromatin-dependent regulatory mechanism at EIN2 requiring two genes: 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 SUBUNIT). Strikingly, EIN6 (REF6) and the INO80 complex redundantly 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 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. These results uncover a unique type of chromatin regulation which safeguards the expression of an essential multifunctional plant stress regulator.

Highlights

The gaseous plant hormone ethylene regulates numerous biological processes ranging from development to responses to environmental stimuli (Johnson and Ecker, 1998)
Through the molecular characterization of the ET-insensitive ein6-1 mutant, we discovered that the major Arabidopsis H3K27me3 demethylase RELATIVE OF EARLY FLOWERING6 (REF6) (Lu et al, 2011) and the INO80 chromatin remodeling complex cooperatively regulate H3K27me3 and H2A.Z occupancy in the 5’ untranslated region (5’UTR) intron of EIN2
We discovered that the ein6-1 mutants carry mutations in two genes that encode the H3K27me3 demethylase REF6 (EIN6) as well as a crucial subunit of the INO80 chromatin remodeling complex (EEN)

Summary

Introduction

The gaseous plant hormone ethylene regulates numerous biological processes ranging from development to responses to environmental stimuli (Johnson and Ecker, 1998). Upon ET perception, EIN2 is no longer phosphorylated by CTR1, resulting in the proteolytic cleavage of EIN2’s C-terminal CEND domain (EIN2C) (Ju et al, 2012; Qiao et al, 2012; Wen et al, 2012). This multifunctional EIN2C has multiple modes of action (Zheng and Zhu, 2016). ET is crucial for the integration of biotic and abiotic stress responses into plant growth pathways (Dubois et al, 2018) which is underscored by the severe stress-related

Methods

Results

Conclusion