Background: Small RNAs (sRNAs) that do not get untranslated into proteins exhibit a pivotal role in the expression regulation of their cognate gene(s) in almost all eukaryotic lineages, including plants. Hitherto, numerous protein families such as Dicer, a unique class of Ribonuclease III, have been reported to be involved in sRNAs processing pathways and silencing. In this study, we aimed to investigate the phylogenetic relationship and evolutionary history of the DCL protein family.
Results: Our results illustrated the DCL family of proteins grouped into four main subfamilies (DCLs 1-4) presented in either Eudicotyledons or Liliopsids. The accurate observation of the phylogenetic trees supports the independent expansion of DCL proteins among the Eudicotyledons and Liliopsids species. They share the common origin, and the main duplication events for the formation of the DCL subfamilies occurred before the Eudicotyledons/Liliopsids split from their ancestral DCL. In addition, shreds of evidence revealed that the divergence happened when multicellularization started and since the need for complex gene regulation considered being a necessity by organisms. At that time, they have evolved independently among the monophyletic lineages. The other finding was that the combination of DCL protein subfamilies bears several highly conserved functional domains in plant species that originated from their ancestor architecture. The conservation of these domains happens to be both lineage-specific and inter lineage-specific. 041b061a72