Development 122, 1253-1260 (1996) 1253 Printed in Great Britain © The Company of Biologists Limited 1996 DEV0049 The homeobox gene GLABRA 2 is required for position-dependent cell differentiation in the root epidermis of Arabidopsis thaliana James D. Masucci1, William G. Rerie2, Daphne R. Foreman1,†, Meng Zhang1, Moira E. Galway1,‡, M. David Marks3 and John W. Schiefelbein1,* 1Department of Biology, University of Michigan, Ann Arbor, MI 48109, USA 2Plant Research Centre, Agriculture Canada, Ottawa, Ontario K1A 0C6, Canada 3Department of Genetics and Cell Biology, University of Minnesota, St. Paul, MN 55108, USA *Author for correspondence (e-mail:
[email protected]) †Present address: Department of Biology, Macalester University, St. Paul, MN 55105, USA ‡Present address: Department of Biology, St. Francis Xavier University, Antigonish, Nova Scotia B2G 2W5, Canada SUMMARY The role of the Arabidopsis homeobox gene, GLABRA 2 hairs, they are similar to atrichoblasts of the wild type in (GL2), in the development of the root epidermis has been their cytoplasmic characteristics, timing of vacuolation, investigated. The wild-type epidermis is composed of two and extent of cell elongation. The results of in situ nucleic cell types, root-hair cells and hairless cells, which are acid hybridization and GUS reporter gene fusion studies located at distinct positions within the root, implying that show that the GL2 gene is preferentially expressed in the positional cues control cell-type differentiation. During the differentiating hairless cells of the wild type, during a development of the root epidermis, the differentiating root- period in which epidermal cell identity is believed to be hair cells (trichoblasts) and the differentiating hairless cells established.