Genome-wide changes in histone H3 lysine 27 trimethylation associated with bud dormancy release in peach

Abstract

Bud dormancy is an evolutionary adaptation of perennial plants to the seasonal fluctuation of temperatures in temperate climates, affected by intrinsic and environmental signals. Recent investigations point to a relevant role of epigenetic mechanisms in the regulation of bud dormancy. We have performed a chromatin immunoprecipitation sequencing (ChIP-seq) analysis of histone H3 lysine-27 trimethylation (H3K27me3), a chromatin mark associated with stable gene silencing, in dormant (D) and dormancy-released (ND) buds of peach (Prunus persica). H3K27me3 regions were more abundant in gene-rich euchromatic zones of chromosomes and associated with gene bodies. The dormancy regulators DORMANCY-ASSOCIATED MADS-box (DAM) 1, DAM4, DAM5 and DAM6 were found significantly enriched in H3K27me3 in ND samples, in close agreement with their dormancy-specific expression. The DAM locus was modified at specific short regions, allowing the uneven regulation of distinct DAM genes. Additional regulatory factors related to meristem activity and flowering genes from Arabidopsis thaliana were differentially H3K27 trimethylated, which suggests that meristem reactivation and flower development could be also epigenetically regulated in reproductive buds of peach. A (GA)n motif and CACTA-type transposon-related sequences were found over-represented in H3K27me3 regions.