Regulation of root hair cell differentiation by R3 MYB transcription factors in tomato and Arabidopsis

Takuji Wada,Rumi Tominaga-Wada

doi:10.3389/fpls.2014.00091

Abstract

CAPRICE (CPC) encodes a small protein with an R3 MYB motif and regulates root hair and trichome cell differentiation in Arabidopsis thaliana. Six additional CPC-like MYB proteins including TRIPTYCHON (TRY), ENHANCER OF TRY AND CPC1 (ETC1), ENHANCER OF TRY AND CPC2 (ETC2), ENHANCER OF TRY AND CPC3/CPC-LIKE MYB3 (ETC3/CPL3), TRICHOMELESS1 (TCL1), and TRICHOMELESS2/CPC-LIKE MYB4 (TCL2/CPL4) also have the ability to regulate root hair and/or trichome cell differentiation in Arabidopsis. In this review, we describe our latest findings on how CPC-like MYB transcription factors regulate root hair cell differentiation. Recently, we identified the tomato SlTRY gene as an ortholog of the Arabidopsis TRY gene. Transgenic Arabidopsis plants harboring SlTRY produced more root hairs, a phenotype similar to that of 35S::CPC transgenic plants. CPC is also known to be involved in anthocyanin biosynthesis. Anthocyanin accumulation was repressed in the SlTRY transgenic plants, suggesting that SlTRY can also influence anthocyanin biosynthesis. We concluded that tomato and Arabidopsis partially use similar transcription factors for root hair cell differentiation, and that a CPC-like R3 MYB may be a key common regulator of plant root-hair development.

Highlights

CAPRICE (CPC) encodes a small protein with an R3 MYB motif and regulates root hair and trichome cell differentiation in Arabidopsis thaliana
Arabidopsis has six additional CPC-like MYB sequences in its genome, including TRY, ENHANCER OF TRY AND CPC1 (ETC1), ENHANCER OF TRY AND CPC2 (ETC2), ETC3/CPL3, TCL1, and TCL2/CPL4 (Hulskamp et al, 1994; Schellmann et al, 2002; Esch et al, 2004; Kirik et al, 2004a,b; Simon et al, 2007; Wang et al, 2007, 2008, 2010; Tominaga et al, 2008; Wester et al, 2009; Gan et al, 2011; Tominaga-Wada and Nukumizu, 2012). These seven CPC-like MYB transcription factors act as positive regulators of root-hair cell differentiation and as negative regulators of trichome differentiation in a partially redundant manner (Tominaga-Wada et al, 2011; Tominaga-Wada and Nukumizu, 2012)
Between CPL4 and ETC2, there were several chimeric transcripts generated through alternative splicing (Tominaga-Wada and Nukumizu, 2012)

Summary

Introduction

CAPRICE (CPC) encodes a small protein with an R3 MYB motif and regulates root hair and trichome cell differentiation in Arabidopsis thaliana. The GL2 gene encodes a homeodomain leucine-zipper protein, and the WER gene encodes an R2R3-type MYB transcription factor that activates GL2 expression preferentially in differentiating non-hair cells (Rerie et al, 1994; Di Cristina et al, 1996; Masucci et al, 1996; Lee and Schiefelbein, 1999). A protein complex including WER, GL3/EGL3, and TTG1 acts upstream of the GL2 gene in the root-hair regulatory pathway and promotes GL2 gene expression (Galway et al, 1994; Rerie et al, 1994; Wada et al, 1997; Hung et al, 1998; Lee and Schiefelbein, 1999; Bernhardt et al, 2003, 2005).

Results

Conclusion