DNA replication-coupled histone modification maintains Polycomb gene silencing in plants [ChIP-Rx]

Propagation of patterns of gene expression through the cell cycle requires prompt restoration of epigenetic marks after the twofold dilution caused by DNA replication. Here, we show that the transcriptional repressive mark histone H3K27 trimethylation (H3K27me3) is restored in replicating plant cells through DNA replication-coupled modification of histone variant H3.1. Plants evolved a mechanism for efficient K27 trimethylation on H3.1, which is essential for inheritance of the silencing memory from mother to daughter cells. We illustrate how this mechanism establishes H3K27me3 mediated silencing during the developmental transition to flowering. Our study reveals transmission of H3K27me3 in plant cells through cell divisions, enabling H3K27me3 to function as an epigenetic mark. Overall design: Comparison of H3K27me3 profiles between Col and h3.1kd lines using ChIP-Rx.