The Evolutionarily Conserved TOUGH Protein Is Required for Proper Development ofArabidopsis thaliana 

Abstract

In this study, we characterize the evolutionarily conserved TOUGH (TGH) protein as a novel regulator required for Arabidopsis thaliana development. We initially identified TGH as a yeast two-hybrid system interactor of the transcription initiation factor TATA-box binding protein 2. TGH has apparent orthologs in all eukaryotic model organisms with the exception of the budding yeast Saccharomyces cerevisiae. TGH contains domains with strong similarity to G-patch and SWAP domains, protein domains that are characteristic of RNA binding and processing proteins. Furthermore, TGH colocalizes with the splicing regulator SRp34 to subnuclear particles. We therefore propose that TGH plays a role in RNA binding or processing. Arabidopsis tgh mutants display developmental defects, including reduced plant height, polycotyly, and reduced vascularization. We found TGH expression to be increased in the amp1-1 mutant, which is similar to tgh mutants with respect to polycotyly and defects in vascular development. Interestingly, we observed a strong genetic interaction between TGH and AMP1 in that tgh-1 amp1-1 double mutants are extremely dwarfed and severely affected in plant development in general and vascular development in particular when compared with the single mutants.

Regulation of miRNA abundance by RNA binding protein TOUGH in Arabidopsis

“…Three facts prompted us to test whether TGH acts in the miRNA pathway. First, TGH is an evolutionarily conserved protein across plant and animal kingdoms (14), agreeing with the fact that many components involved in miRNA biogenesis are conserved in eukaryotes (1). Second, TGH contains a G-patch and a SWAP domain (Suppressor-of-White-APricot) that often exist within RNA metabolism-related proteins (14) (Fig.…”

“…S1A). Finally, like dcl1, ddl, hyl1, and abh1, which are deficient in the miRNA pathway, the tgh mutants exhibit pleiotropic developmental defects such as smaller plant size, altered leaf shape, short stature, increased branches, disordered node distribution, and reduced fertility (14)(15)(16)(17)(18)(19)(20) (Fig. S1B).…”

“…To determine whether TGH functions in miRNA biogenesis, we examined the accumulation of various DCL1-dependent miRNAs in inflorescences of tgh-1 (SALK_053445), which contains a T-DNA insertion in the 11th intron and is a potential null allele (14) (Fig. S1A).…”

The dicer-like1 Homolog fuzzy tassel Is Required for the Regulation of Meristem Determinacy in the Inflorescence and Vegetative Growth in Maize

“…In rice, strong DCL1 RNA interference knockdowns result in developmental arrest, while weak knockdowns exhibit defects in plant growth, shoot, root, and leaf development (Liu et al, 2005). In addition, Arabidopsis mutants in other miRNA biogenesis enzymes, including hyl1, se, tgh, ddl, abh1, and hen1, have pleiotropic developmental defects, presumably due to the misregulation of miRNA target mRNAs (Clarke et al, 1999;Lu and Fedoroff, 2000;Hugouvieux et al, 2001;Prigge and Wagner, 2001;Chen et al, 2002;Calderon-Villalobos et al, 2005;Morris et al, 2006;Yang et al, 2006). We isolated a maize mutant, fuzzy tassel (fzt), with a broad range of vegetative and reproductive defects.…”

Post-transcriptional control of miRNA abundance in Arabidopsis

“…TGH contains a G-patch and a SWAP domain in its N-terminus, which are often found in RNA binding and/or processing related proteins. 39 TGH binds both pri-miRNAs and pre-miRNAs and interacts with DCL1, HYL1 and SE. 37 Mutation of TGH impairs DCL1 activities in vitro Most pri-miRNAs use a conical "base" to "loop" processing pathway.…”