Dynamics and inheritance of the paternal epigenome

During plant sexual reproduction, the paternal epigenome is remodelled as it progresses from meiocyte to sperm cell and, after fertilization, to the zygote. In flowering plants, sperm cells retain a condensed chromatin state, specialized histone variants and a relatively stable DNA methylation landscape, whereas the companion vegetative cell undergoes chromatin decondensation, DNA demethylation and transposon reactivation. These contrasting epigenetic states are associated with small RNA production and reinforce genome integrity in the male germline. Following fertilization, sperm-specific histone variants are rapidly removed, and DNA methylation is also reinforced during embryogenesis, a process that may involve mobile maternal small RNAs. We present recent advances in our understanding of the regulation of chromatin states and DNA methylation during male gametogenesis, and discuss how paternal epigenetic information is transmitted, reset or re-established in the early embryo.