HDG1 transcription factor targets

The AIL transcription factor BABY BOOM (BBM) is required together with the related PLETHORA proteins for embryo and root meristem development and its expression is sufficient to confer pluripotency and totipotency to somatic tissues. We show that BBM and other AIL proteins interact with multiple members of the L1/epidermal-expressed HD-ZIP class IV / HOMEODOMAIN GLABROUS (HDG) transcription factor family. Ectopic overexpression of HDG1, HDG11 and HDG12 genes induces a reduced growth phenotype, and analysis of HDG1 overexpression lines shows that this growth reduction is due to both root and shoot meristem arrest. To understand how HDG1 controls cell proliferation, as well as its functional relationship with BBM, we performed microarray experiments to identify candidate genes that are directly regulated by HDG1, and compared these to the set of genes that are directly regulated by BBM expression. Transcriptomic profiling was done after 8 hours of dexamethasone induction of 35S::GR-HDG1 and wild-type Col-0 seedlings and significantly differentially expressed genes were identified as HDG1 targets.