The <i>TRANSPARENT TESTA GLABRA1</i> Locus, Which Regulates Trichome Differentiation and Anthocyanin Biosynthesis in Arabidopsis, Encodes a WD40 Repeat Protein

TLDR

The TTG1 locus in Arabidopsis regulates trichome development, seed mucilage, and anthocyanin production, and its WD40 protein is related to G protein β subunits, implying a role in signal transduction. TTG1 was isolated by positional cloning, confirmed by complementation, encodes a 341‑residue WD40 protein, is expressed in all major organs, and mutant alleles reveal truncations or amino‑acid changes.

Abstract

The TRANSPARENT TESTA GLABRA1 (TTG1) locus regulates several developmental and biochemical pathways in Arabidopsis, including the formation of hairs on leaves, stems, and roots, and the production of seed mucilage and anthocyanin pigments. The TTG1 locus has been isolated by positional cloning, and its identity was confirmed by complementation of a ttg1 mutant. The locus encodes a protein of 341 amino acid residues with four WD40 repeats. The protein is similar to AN11, a regulator of anthocyanin biosynthesis in petunia, and more distantly related to those of the β subunits of heterotrimeric G proteins, which suggests a role for TTG1 in signal transduction to downstream transcription factors. The 1.5-kb TTG1 transcript is present in all major organs of Arabidopsis. Sequence analysis of six mutant alleles has identified base changes producing truncations or single amino acid changes in the TTG1 protein.