Dynamics of histone H3 lysine 27 trimethylation in plant development

Abstract

The development of multicellular organisms is governed partly by temporally and spatially controlled gene expression. DNA methylation, covalent modifications of histones, and the use of histone variants are the major epigenetic mechanisms governing gene expression in plant development. In this review, we zoom in onto histone H3 lysine 27 trimethylation (H3K27me3), a repressive mark that plays a crucial role in the dynamic regulation of gene expression in plant development, to discuss recent advances as well as outstanding questions in the deposition, recognition, and removal of the mark and the impacts of these molecular processes on plant development.

Figure 1

A diagram of the compositions of PcG and mechanisms of its recruitment to targets. (A) Composition of a PRC2 complex and its recruitment to the FLC gene by a noncoding RNA. The VRN2 complex is composed of CLF and/or its paralog SWN, FIE, MSI and VRN2. A vernalization response element (VER) in the first intron of the PcG target FLC serves as a promoter for the transcription of a noncoding RNA (COLDAIR), which binds CLF and recruits PRC2 to FLC. Pol II is probably the polymerase that produces COLDAIR. By analogy to findings from animal systems, CLF may recognize short stem-loop features within COLDAIR. (B) Composition of a PRC1-like complex and its recruitment to the SEPALLATA3 (SEP3) gene. A plant PRC1 complex likely consists of TFL2, AtRING1A/AtRING1B, AtBMI1A/AtBMI1B, and EMF1. The transcription factor SVP binds to its specific recognition site known as a CArG box in SEP3 and recruits TFL2 to SEP3.