The bHLH genes GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3) specify epidermal cell fate in the Arabidopsis root

Christine Bernhardt, Myeong Min Lee, Antonio Gonzalez, Fan Zhang, Alan Lloyd, John Schiefelbein

Research output: Contribution to journalArticlepeer-review

327 Citations (Scopus)


The position-dependent specification of the hair and non-hair cell types in the Arabidopsis root epidermis provides a simple model for the study of cell fate determination in plants. Several putative transcriptional regulators are known to influence this cell fate decision. Indirect evidence from studies with the maize R gene has been used to suggest that a bHLH transcription factor also participates in this process. We show that two Arabidopsis genes encoding bHLH proteins, GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), act in a partially redundant manner to specify root epidermal cell fates. Plants homozygous for mutations in both genes fail to specify the non-hair cell type, whereas plants overexpressing either gene produce ectopic non-hair cells. We also find that these genes are required for appropriate transcription of the non-hair specification gene GL2 and the hair cell specification gene CPC, showing that GL3 and EGL3 influence both epidermal cell fates. Furthermore, we show that these bHLH proteins require a functional WER MYB protein for their action, and they physically interact with WER and CPC in the yeast two-hybrid assay. These results suggest a model in which GL3 and EGL3 act together with WER in the N cell position to promote the non-hair cell fate, whereas they interact with the incomplete MYB protein CPC in the H position, which blocks the non-hair pathway and leads to the hair cell fate.

Original languageEnglish
Pages (from-to)6431-6439
Number of pages9
Issue number26
Publication statusPublished - 2003 Dec

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology


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