Molecular identification of histone acetyltransferases and deacetylases in lower plant Marchantia polymorpha

Histone is the core component of nucleosome and modification of amino acid residues on histone tails is one of the most pivotal epigenetic regulatory mechanisms. Histone acetylation or deacetylation is carried out by two groups of proteins: histone acetyltransferases (HATs) or histone deacetylases (HDACs), and has been proven to be tightly linked to regulation of gene expression in animals and vascular plants. The biological functions of HATs and HDACs in non-flowering plants remain largely unknown. We found that there are seven MpHAT genes and twelve MpHDAC genes present in the Marchantia genome, and the comprehensive protein sequence analysis of the HAT and HDAC families was introduced to investigate their potential functions. On the basis of the functional domain analysis, eight MpHATs and twelve MpHDACs contain the conserved functional domains as the defining feature of each family. Phylogenetic trees of all families of MpHATs and MpHDACs along with their homologs from different plant and green algae species were constructed to illustrate evolutionary relationship of HAT and HDAC proteins. We found both SIR2 family and RPD3/HDA1 superfamily possess lower plant-specific proteins indicating the potential unknown functions of HATs and HDACs in Marchantia and other lower plant or algae species. Subcellular localization prediction suggests that MpHATs and MpHDACs are likely functioning in various organelles. Expression analysis shows that all MpHAT and MpHDAC genes are expressed in all tissues with differences at the transcriptional level. In addition, their expression patterns were altered in response to various treatments with plant hormones and environmental stress. We concluded that all MpHATs and MpHDACs are functional proteins in Marchantia and involved in various signaling pathways. Marchantia could have developed a complex histone acetylation epigenetic mechanism to regulate growth and development, as well as responses to environment.