439 / 2019-01-31 22:03:08

Role of histone H2A ubiquitination in the liverwort Marchantia polymorpha

H2Aub, ABA, dormancy

全体主题 > Epigenetics

Monoubiquitination of histone H2A (H2Aub) is a repressive epigenetic mark deposited on the C-terminal lysine of H2A by the Polycomb Repressive Complex 1 (PRC1). H2Aub marks are widespread in Arabidopsis and often co-localize with H3 lysine 27 tri-methylation (H3K27me3) which is catalyzed by the PRC2; nevertheless, recent work revealed that H2Aub is independent of PRC2 activity (Zhou et al., 2017). Therefore, the mechanism by which H2Aub confers gene repression and the relationship between H2Aub and H3K27me3 are still poorly understood in plants.
In the liverwort Marchantia polymorpha H2A is encoded by a single gene, while there are four H2A encoding homologs in Arabidopsis. I introduced H2A variants containing mutated lysine 115, 116 and 119 into an H2A deficient background of M. polymorpha, causing a substantial loss of H2Aub levels. The H2Aub depleted mutants show severe morphological defects and reduced gemma dormancy, supporting an important functional role of H2Aub in regulating gene expression. The plant hormone abscisic acid (ABA) has been demonstrated to play a central role in the control of gemma dormancy in M. polymorpha (Eklund et al., 2018). Here, we show that H2Aub regulates gemma dormancy in an ABA-dependent manner. H2Aub regulates ABA catabolism related genes by affecting the deposition of H3K27me3, indicating that PRC2-mediated repression relies on H2Aub in maintaining gemma dormancy.