The 30th International Conference on Arabidopsis Research (ICAR 2019)

614 / 2019-04-24 08:48:24

Epigenetic regulation of vegetative phase change

vegetative phase change, miR156, H3K27me3, H3K4me3

Plenary track > Epigenetics

There are two important post-embryonic transitions in flowering plants: the juvenile-to-adult vegetative transition and the vegetative-to-reproductive transition. Vegetative phase change is mediated by a decrease in the expression of miR156, and a corresponding increase in its direct targets, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. Understanding how miR156 is regulated is therefore important for understanding the mechanism of vegetative phase change. I found that changes in chromatin structure play a critical role in this process. In particular, we found that the CHD3 chromatin remodeler, PICKLE (PKL), and the Polycomb Repressive Complex 2 (PRC2) component, SWINGER (SWN), are required for the down-regulation of MIR156A and MIR156C, two major sources of miR156. PKL stabilizes the +1 nucleosome, and promotes the loss of the active chromatin mark, H3K27ac, and the deposition of the repressive mark, H3K27me3 at these loci. The deposition of H3K27me3 at these genes is mediated primarily by the histone methyltransferase, SWN. In addition, MIR156A and MIR156C are also marked by the active chromatin mark H3K4me3, and the chromatin remodeler ACTIN-RELATED PROTEIN6 (ARP6), part of the SWR complex, facilitates the deposition of Hem4me3 and promotes the high expression of miR156 early in development. Our research has yielded new insights into how vegetative phase change is regulated epigenetically and provides a foundation for future studies.