WIN1 /SHN1 gain-of-function mutants from Arabidopsis thaliana and barley ( Hordeum vulgare) have been reported ( Aharoni et al., 2004 Taketa et al., 2008). The most intensively studied TFs involved in cuticle development are WAX INDUCER1 (WIN1)/SHINE1 (SHN1) and its phylogenetic neighbors in the AP2/ERF family. In addition to the known biosynthetic mutants, several transcription factors ( TFs) have been shown to regulate cuticle biosynthesis. Many mutants defective in wax or cutin biosynthesis have been reported, including mutants of genes required for the elongation of very-long-chain fatty acids and mutants of genes required for cutin monomer biosynthesis these mutants exhibit permeable cuticles, loss of epicuticular wax, and/or loss of cutin nanoridges on the surface of flowers ( Jenks et al., 1995 Tanaka et al., 2004 Li-Beisson et al., 2009). Wax and cutin composition, secretion, and synthesis are modulated during cell expansion ( Suh et al., 2005) and vary in different tissues ( Li et al., 2007 Li-Beisson et al., 2009). The cuticle is secreted from epidermal cells to the outside of the cell wall and serves to attract pollinators, to protect plants from dehydration, pathogen, and insect attacks, and to prevent organ fusion. The plant cuticle, which covers the surface of epidermal cells, consists of the lipophilic polymer cutin and cuticular waxes, which are synthesized from long-chain fatty acids. This study reveals an additional key aspect of MIXTA-like protein function and suggests a unique relationship between cuticle development and epidermal cell differentiation. These results indicate that the regulatory cascade of MIXTA-like proteins and WIN1/SHN1 coordinately regulate cutin biosynthesis and wax accumulation. Furthermore, WIN1/SHN1 expression was induced by MYB106-VP16 and repressed by MYB106-SRDX. Microarray experiments revealed that MYB106 and WIN1/SHN1 regulate similar sets of genes, predominantly those involved in wax and cutin biosynthesis. Conversely, the dominant active form of MYB106 ( 35S: MYB106-VP16) induced ectopic production of cutin nanoridges and increased expression of WIN1/SHN1 and wax biosynthetic genes. A similar organ fusion phenotype was produced by expression of a WIN1/SHN1 chimeric repressor. Expression of a MYB106 chimeric repressor fusion ( 35S: MYB106-SRDX) and knockout/down of MYB106 and MYB16 induced cuticle deficiencies characterized by organ adhesion and reduction of epicuticular wax crystals and cutin nanoridges. Here, we show that the MIXTA-like MYB transcription factors MYB106 and MYB16, which regulate epidermal cell morphology, also regulate cuticle development coordinately with WIN1/SHN1 in Arabidopsis and Torenia fournieri. The transcription factor WAX INDUCER1/SHINE1 (WIN1/SHN1) regulates the biosynthesis of waxy substances in Arabidopsis thaliana. This sequence-specific transcriptional repression by direct on promoter effector technology is a powerful tool for functional genomics studies and biotechnological applications. Our data suggest that TALEs can be used to generate chimeric repressors to specifically repress the transcription of genes of interest in plants. Genome wide expression profiling showed that the chimeric repressor also inhibited the expression of several other genes that contain the designer TALE-target sequence in their promoters. The dHax3.SRDX protein efficiently repressed the transcription of the RD29A::LUC transgene and endogenous RD29A gene in Arabidopsis. The dHax3 TALE was used as a scaffold to provide a DNA-binding module fused to the EAR-repression domain (SRDX) to generate a chimeric repressor that targets the RD29A promoter. Here we report the use of TALEs to generate chimeric sequence-specific transcriptional repressors. TALEs contain a modular DNA binding domain that can be easily engineered to bind any sequence of interest, and have been used to provide user-selected DNA-binding modules to generate chimeric nucleases and transcriptional activators in mammalian cells and plants. Transcriptional activator-like effectors (TALEs) are proteins secreted by Xanthomonas bacteria when they infect plants.

Srdx transcription