Histone deacetylase AtHDA7 is required for female gametophyte and embryo development in Arabidopsis

Histone modifications are involved in the regulation of many processes in eukaryotic development. In this work, we provide evidence that AtHDA7, a HDAC of RPD3 superfamily, is crucial for female gametophyte development and embryogenesis in Arabidopsis. Silencing of AtHDA7 causes degeneration of micropilar nuclei at the stage of four-nucleate embryo sac and delay in the progression of embryo development, thereby bringing the seed-set down in Athda7-2 mutant. Furthermore, AtHDA7 down- and up-regulation lead to a delay of growth in post-germination and later developmental stages. Athda7-2 mutation that induces histone hyperacetylation significantly increases transcription of other HDACs (AtHDA6 and AtHDA9). Moreover, silencing of AtHDA7 affects the expression of ARABIDOPSIS HOMOLOG OF SEPARASE (AtAESP), previously demonstrated to be involved in female gametophyte and embryo development. However, ChIP analysis with acetylated H3 antibody provided evidence that the acetylation levels of H3 at AtAESP and HDACs does not change in the mutant. Further investigations are essentialto ascertain the mechanism by which AtHDA7 affects female gamethophyte and embryo development.