Repression of FLOWERING LOCUS T Chromatin by Functionally Redundant Histone H3 Lysine 4 Demethylases in Arabidopsis

Abstract

FLOWERING LOCUS T (FT) plays a key role as a mobile floral induction signal that initiates the floral transition. Therefore, precise control of FT expression is critical for the reproductive success of flowering plants. Coexistence of bivalent histone H3 lysine 27 trimethylation (H3K27me3) and H3K4me3 marks at the FT locus and the role of H3K27me3 as a strong FT repression mechanism in Arabidopsis have been reported. However, the role of an active mark, H3K4me3, in FT regulation has not been addressed, nor have the components affecting this mark been identified. Mutations in Arabidopsis thaliana Jumonji4 (AtJmj4) and EARLY FLOWERING6 (ELF6), two Arabidopsis genes encoding Jumonji (Jmj) family proteins, caused FT-dependent, additive early flowering correlated with increased expression of FT mRNA and increased H3K4me3 levels within FT chromatin. Purified recombinant AtJmj4 protein possesses specific demethylase activity for mono-, di-, and trimethylated H3K4. Tagged AtJmj4 and ELF6 proteins associate directly with the FT transcription initiation region, a region where the H3K4me3 levels were increased most significantly in the mutants. Thus, our study demonstrates the roles of AtJmj4 and ELF6 as H3K4 demethylases directly repressing FT chromatin and preventing precocious flowering in Arabidopsis.

Tissue-Specific Expression of FLOWERING LOCUS T in Arabidopsis Is Maintained Independently of Polycomb Group Protein Repression

“…However, genome-wide data in Arabidopsis did not show a general association between H3K4me3 and H3K27me3 (Ha et al, 2011). Despite previous results (Jiang et al, 2008;Carles and Fletcher, 2009;Jeong et al, 2009), our ChIP experiments did not confirm any significant change for H3K4me3 in the clf background either at FT or AG. An increase for this mark was observed in swn clf plants, despite the repression of FT. Lafos et al have recently shown that H3K4me3 levels increase globally in swn clf calli, which may explain why higher levels were detected at the FT locus (Lafos et al, 2011).…”

“…In animal stem cells, active and repressive chromatin marks are present at the same developmental loci and poise their targets for activation or repression during differentiation (Fisher and Fisher, 2011). In Arabidopsis, bivalent chromatin was demonstrated for FT and FLC (Jiang et al, 2008), and a role of bivalent chromatin in finetuning FLC and FT expression was suggested (Jiang et al, 2008;Carles and Fletcher, 2009;Jeong et al, 2009). However, genome-wide data in Arabidopsis did not show a general association between H3K4me3 and H3K27me3 (Ha et al, 2011).…”

TheFT-LikeZCN8Gene Functions as a Floral Activator and Is Involved in Photoperiod Sensitivity in Maize

“…This may explain how ZCN8 expression is maintained in the vascular cells of the mature leaf blade, which are many mitotic generations removed from when id1 was active. Recently, several studies have shown that FT is subject to epigenetic regulation as one of several inputs required for its expression (Jiang et al, 2008;Jeong et al, 2009;Adrian et al, 2010;Yang et al, 2010), but this idea remains to be studied in maize.…”

Jumonji demethylases moderate precocious flowering at elevated temperature via regulation of FLC in Arabidopsis

“…There are 21 JUMONJI (JMJ) genes in Arabidopsis, which can be categorized into five groups, namely the KDM5/JARID1, KDM4/JHDM3/ JMJD2, KDM3/JHDM2, JMJD6 and JmjC domain-only group, based on their JmjC domain sequences and domain architectures 22,23 . Members from the same group show similar target specificity for histone modifications [24][25][26][27][28][29][30][31][32] . One of the histone modifications, the repressive PcG-mediated H3K27me3, plays a key role in gene repression and developmental regulation, and is actively and dynamically deposited and removed in plants 33 .…”