Song SK, Ryu KH, Kang YH, Song JH, Cho YH, Yoo SD, Schiefelbein J, Lee MM

The root hair and non-hair cells in the Arabidopsis (Arabidopsis thaliana) root epidermis are specified by a suite of transcriptional regulators. Two of these are WEREWOLF (WER) and CAPRICE (CPC), which encode MYB transcription factors that are required for promoting the non-hair cell fate and the hair cell fate, respectively. ...

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However, the precise function and relationship between these transcriptional regulators has not been fully defined experimentally. Here we examine these issues by misexpressing the WER gene using the GAL4-UAS trans-activation system. We find that WER overexpression in the Arabidopsis root tip is sufficient to cause epidermal cells to adopt the non-hair cell fate through direct induction of GLABRA2 (GL2) gene expression. We also show that GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3), two closely related bHLH proteins, are required for the action of the overexpressed WER, and that WER interacts with these bHLHs in plant cells. Furthermore, we find that CPC suppresses the WER overexpression phenotype quantitatively. These results show that WER acts together with GL3/EGL3 to induce GL2 expression, and that WER and CPC compete with one another to define cell fates in the Arabidopsis root epidermis.

Date: Sep. 13, 2011

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