Seuss Integrates Transcriptional And Epigenetic Control Of Root Stem Cell Organizer Specification

Proper regulation of homeotic gene expression is critical for stem cell fate in both plants and animals. InArabidopsis thaliana, theWUSCHEL(WUS)-RELATED HOMEOBOX 5(WOX5) gene is specifically expressed in a group of root stem cell organizer cells called the quiescent center (QC) and plays a central role in QC specification. Here, we report that the SEUSS (SEU) protein, homologous to the animal LIM-domain binding (LDB) proteins, assembles a functional transcriptional complex that regulatesWOX5expression and QC specification. SEU is physically recruited to theWOX5promoter by the master transcription factor SCARECROW. Subsequently, SEU physically recruits the SET domain methyltransferase SDG4 to theWOX5promoter, thus activatingWOX5expression. Thus, analogous to its animal counterparts, SEU acts as a multi-adaptor protein that integrates the actions of genetic and epigenetic regulators into a concerted transcriptional program to control root stem cell organizer specification.