In Vivo Interference with AtTCP20 Function Induces Severe Plant Growth Alterations and Deregulates the Expression of Many Genes Important for Development  

Abstract

AtTCP20 is a transcription factor belonging to the Arabidopsis (Arabidopsis thaliana) TCP-P subfamily, characterized by its capacity to bind to site II motifs (TGGGCY). Our aim was to understand the role of AtTCP20 in plant development. The expression pattern of a translational fusion of PromTCP20:CDS20∷GUS∷GFP suggested a function for AtTCP20 in several plant organs and stages of development. The role of AtTCP20 was challenged in planta by inducing expression of AtTCP20 proteins fused with either a transcriptional activator domain (VP16) or a repressor domain (EAR). Expression of both modified proteins led to severe developmental phenotypes. In-depth analysis suggested that AtTCP20 may participate in the regulation of cell expansion, cell division, and cell differentiation. Gene expression profiling in roots and hypocotyls revealed that 252 genes were down-regulated in both organs after induction of the AtTCP20∷EAR repressor gene. Site II motifs (TGGGCY) were underrepresented in their promoters. Conversely, GG(A/T)CCC sequences related to binding sites identified for TCP proteins in rice (Oryza sativa) were overrepresented, and a TCP20 fusion protein was shown to bind to these sequences in vitro. Gene ontology indicated that many targeted genes were involved in cell wall biogenesis and modification during expansion and also encoded numerous transcription factors controlling plant development. Our results are consistent with the previous proposal that AtTCP20 is involved in cell division and growth coordination. Moreover, they further suggest that AtTCP20 also contributes to cell expansion control and indicate a different involvement of this protein in plant morphogenesis depending on the organ and the developmental stage.

The Cotton Transcription Factor TCP14 Functions in Auxin-Mediated Epidermal Cell Differentiation and Elongation

“…It has been suggested that TCP proteins may function either as transcriptional activators or repressors, depending on their interactions with other proteins (Hervé et al, 2009). As the GhTCP14-overexpressing plants phenocopied auxin distribution mutants such as pin2, we analyzed the expression of PIN2 and other auxin-related genes in the transgenic plants and found that the expression of several auxin-related genes was either increased or decreased.…”

“…The distinctive activities of GhTCP14 may depend on its interaction with other proteins (Hervé et al, 2009).…”

“…Accumulating evidence demonstrates that TCP transcription factors play important roles in plant growth and development (Cubas et al, 1999;Li et al, 2005;Hervé et al, 2009). In particular, great progress has been made in functional characterization of the class II TCPs in Arabidopsis.…”

“…The cellular functions of class I TCPs are less well explored, but several previous studies indicated that they are involved in a number of cellular or developmental processes. For example, Arabidopsis AtTCP14 and AtTCP16 participate in regulation of seed germination and pollen development, respectively (Takeda et al, 2006;Tatematsu et al, 2008a), and AtTCP20 and AtTCP15 are involved in the regulation of cell division, expansion, and differentiation (Hervé et al, 2009;Kieffer et al, 2011). In addition, several lines of evidence have demonstrated that the functions of class I TCP proteins are associated with phytohormone signaling, such as auxin, jasmonic acid (JA), and cytokinin (Kosugi and Ohashi, 2002;Danisman et al, 2012;Steiner et al, 2012;Uberti-Manassero et al, 2012).…”

Transcriptomic Analysis Reveals Calcium Regulation of Specific Promoter Motifs inArabidopsis

“…In Arabidopsis, the same Site II sequence GGCCCA and slight variations are bound by a family of transcription factors known as the TCP family, which share sequence similarity with rice PCF1/PCF2 (reviewed in Martín-Trillo and Cubas, 2010). The Arabidopsis TCP proteins, and their binding motif, have been described on many occasions as regulatory elements involved in regulating genes required for cell cycle control, growth, and development (Tré mousaygue et al, 2003;Li et al, 2005;Gonzalez, 2005, 2006;Hervé et al, 2009;Pruneda-Paz et al, 2009). To our knowledge, there have been no previous reports of the involvement of calcium signaling upstream of this cis-element or its transcription factors.…”