Journal of Integrative Plant Biology, 54 (10) : 729-737, Oct 2012     Research Article

Pathways for Epidermal Cell Differentiation via the Homeobox Gene GLABRA2: Update on the Roles of the Classic Regulator

Qing Lin 1 and Takashi Aoyama2
1State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
2Institute for Chemical Research, Kyoto University, Uji, Kyoto 611ĘC0011, Japan

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Online on 3 Sept 2012 at and


Recent plant development studies have identified regulatory pathways for epidermal cell differentiation in Arabidopsis thaliana. Interestingly, some of such pathways contain transcriptional networks with a common structure in which the homeobox gene GLABLA2 (GL2) is downstream of the transactivation complex consisting of MYB, bHLH, and WD40 proteins. Here, we review the role of GL2 as an output device of the conserved network, and update the knowledge of epidermal cell differentiation pathways downstream of GL2. Despite the consistent position of GL2 within the network, its role in epidermal tissues varies; in the root epidermis, GL2 promotes non-hair cell differentiation after cell pattern formation, whereas in the leaf epidermis, it is likely to be involved in both pattern formation and differentiation of trichomes. GL2 expression levels act as quantitative factors for initiation of cell differentiation in the root and leaf epidermis; the quantity of hairless cells in non-root hair cell files is reduced by gl2 mutations in a semi-dominant manner, and entopically additive expression of GL2 and a heterozygous gl2 mutation increase and decrease the number of trichomes, respectively. Although few direct target genes have been identified, evidence from genetic and expression analyses suggests that GL2 directly regulates genes with various hierarchies in epidermal cell differentiation pathways.

Qing L, Aoyama T (2012) Pathways for epidermal cell differentiation via the homeobox gene GLABRA2: Update on the roles of the classic regulator. J. Integr. Plant Biol. 54(10), 729–737.

Received 30 July 2012   Accepted 26 Aug 2012
© 2017 Institute of Botany, Chinese Academy of Sciences

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