Arabidopsis EML histone readers are essential for seed development

Abstract

Histone post-translational modifications (PTMs) and their recognition by histone readers, play a major role in regulating gene expression. Despite extensive studies, there is a lack of systematic knowledge of histone readers in plants. EMSY-like (EML) gene family was identified in Arabidopsis thaliana (Arabidopsis) based on homology with maize RIF1. RIF1 and EML proteins share a unique protein domain organization, characterized by the ENT and AGENET domains, found only in proteins with chromatin-associated functions. We demonstrated that EML1 and EML3 bind histone H3 lysine 36 (H3K36), a PTM usually associated with active gene expression and that they are localized in different compartments during seed development. To functionally characterize Arabidopsis EML proteins, we generated eml1-2, and eml3-4 homozygous single mutant, as well as eml1-2 eml3-4 double mutant stocks. Consistent with their localization pattern, mutants in EML1 or EML3 showed delayed embryo development, while in the eml1-2 eml3-4 we observed a more significant delay compared with its WT. In addition, combined loss of function of EML1 and EML3 displayed early seed abortion and also caused ovule abortion, suggestive of a synergistic effect. Therefore, our preliminary results suggest that EML genes, specific histone mark readers in seeds, have an essential role in seed development.