Impact of core histone modifications on transcriptional regulation and plant growth

In eukaryotic organisms a wide range of regulatory mechanisms are required to complete the developmental program. Recently, the information contained in the histone code has been recognized to offer an additional mode of regulation of many processes in development. The histone code consists of covalent modifications of the core histone tails by ubiquitination, acetylation, methylation, ribosylation, sumoylation, phosphorylation, carbonylation, and glycation and the cross-talk between these modifications. These modifications reversibly alter the accessibility of the genome by the transition from heterochromatin to euchromatin and vice versa and play a role in almost all aspects of DNA metabolism: transcription, DNA repair, DNA recombination, and DNA replication. This review highlights the mechanisms that regulate the transcriptional activation or repression through modification of core histone tails and how these processes affect plant development. Chromatin control of leaf and root growth and the developmental transition from vegetative to reproductive phase is emphasized. In addition, the environmental impact on histone modifications will be discussed to support the view that chromatin acts as an interface to sense external signals and to regulate RNAPII transcription activity to adjust growth and developmental transitions.