title: Participation of the Arabidopsis bHLH factor GL3 in trichome initiation regulatory events.
abstract: The development of trichomes (leaf hairs) from pluripotent epidermal cells in Arabidopsis (Arabidopsis thaliana) provides a powerful system to investigate the regulatory motifs involved in plant cell differentiation. We show here that trichome initiation is triggered within 4 h of the induction of the GLABRA3 (GL3) basic helix-loop-helix transcription factor. Within this developmental window, GL3 binds to the promoters of at least three genes previously implicated in the development and patterning of trichomes (GL2, CAPRICE, and ENHANCER OF TRIPTYCHON AND CAPRICE1) and activates their transcription. The in vivo binding of GL3 to the promoters of these genes requires the presence of the R2R3-MYB factor GL1, supporting a model in which a GL3-GL1 complex is part of the trichome initiation enhanceosome. In contrast, GL3 is recruited to its own promoter in a GL1-independent manner, and this results in decreased GL3 expression, suggesting the presence of a GL3 negative autoregulatory loop. In support of genetic analyses indicating that ENHANCER OF GL3 (EGL3) is partially redundant with GL3, we show that EGL3 shares some direct targets with GL3. However, our results suggest that GL3 and EGL3 work independently of each other. Taken together, our results provide a regulatory framework to understand early events of epidermal cell differentiation.
authors: Department of Plant Cellular and Molecular Biology , The Ohio State University, Columbus, Ohio 43210, USA.
authors: Kengo
authors: K
authors: Morohashi
authors: Mingzhe
authors: M
authors: Zhao
authors: Manli
authors: M
authors: Yang
authors: Betsy
authors: B
authors: Read
authors: Alan
authors: A
authors: Lloyd
authors: Rebecca
authors: R
authors: Lamb
authors: Erich
authors: E
authors: Grotewold
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D018744:DNA, Plant; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D018515:Plant Leaves / Q000378:metabolism* / Q000648:ultrastructure; D011401:Promoter Regions, Genetic; D011485:Protein Binding
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D018744:DNA, Plant; C417284:GL3 protein, Arabidopsis