Epigenetic silencing of a multifunctional plant stress regulator

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.

MSH1-induced heritable enhanced growth vigor through grafting is associated with the RdDM pathway in plants

“…3e ). Consistent with an earlier report of msh1 epigenetic memory 16 and other studies 22 , 23 , these observations infer epigenomic responsiveness of phytohormone networks, particularly as relates directly or indirectly to auxin.…”

PHYTOCHROME INTERACTING FACTORs Trigger Environmentally Responsive Chromatin Dynamics

“…Next, we examined the impact of low R:FR exposure on the H2A.Z landscape in WT seedlings in a LD time course experiment (ZT0 -ZT20). In line with previous studies (8,17,18), H2A.Z was specifically enriched in gene bodies of up to 20411 protein-coding genes ( Fig. S2A, Table S2).…”

“…In humans, yeast and Arabidopsis, H2A.Z eviction is facilitated by the SWI/SNF-type ATPdependent chromatin remodeler INO80 (8,20,21). In addition, the histone chaperone ANP32E was also reported to mediate H2A.Z eviction in humans (22,23).…”

“…pif4-101 (25), pif5-2 (26), pif5-3 (26), pif7-1 (27), pif4-101 pif5-3 (25), pif4-2 pif7-1 (27), pif1-1 pif3-3 pif4-2 pif5-3 (28), phyB-9 (29), phyB-9 pif4-101 (25), phyB-9 pif7-1 (27), arp5-1 (30), een-2 (8) and ino80-8 (8) were described previously. By crossing these lines following mutant combinations were generated for this study: pif5-3 pif7-1, pif4-2 pif5-3 pif7-1, pif1-1 pif3-3 pif4-2 pif5-3 pif7-1, phyB-9 pif5-2, phyB-9 pif4-101 pif5-2, phyB-9 pif4-101 pif7-1, phyB-9 pif5-2 pif7-1, phyB-9 pif4-101 pif5-2 pif7-1 and ino80-8 een-2.…”

“…The evolutionary conserved histone variant H2A.Z has emerged as a key regulator of plant environment interactions (4-7) and has been postulated to function as temperature sensor in Arabidopsis (5). As a result of its eviction from gene bodies, H2A.Z chromatin dynamics enable rapid transcriptional responses to various environmental stimuli in Arabidopsis (6)(7)(8). While the current model suggests that H2A.Z occupancy modulates PIF4 binding, this supposition is solely based on the ambient temperatureinduced binding of PIF4 to the FLOWERING LOCUS T (FT) gene (4).…”