Transparent Testa Glabra 1 (TTG1) and TTG1-like genes in Matthiola incana R. Br. and related Brassicaceae and mutation in the WD-40 motif.
TTG1 (Transparent Testa Glabra 1), a WD-40 repeat protein, is involved in regulation of flavonoid/anthocyanin biosynthesis, seed coat (mucilage) development/pigmentation and trichome formation in leaves. Here, we characterized the TTG1 gene of Matthiola incana wild type (e locus), showing 85.3% similarity to TTG1 of A. thaliana on the nucleotide level and 96.2% on the protein level. A white-flowered and glabrous mutant, line 17, of M. incana exhibits one nucleotide change, leading to an amino acid substitution directly in the WD motif (W158R). Correspondingly, the DFR (dihydroflavonol 4-reductase) gene, in which the expression is known to be dependent on TTG1, is not expressed in Matthiola mutant lines 17 (and 19). Comparison of the GC content of the Matthiola TTG1 (54.1%) and Arabidopsis TTG1 (46.1%) genes revealed a strong difference, mostly obtained by neutral substitutions (C to T transitions). To examine whether this is an ecologically influenced trend, a fragment of TTG1 was characterized from another Matthiola species (M. tricuspidata) and from Malcolmia flexuosa subsp. naxensis from the eastern Mediterranean, near a beach with sandy and salty soils. Both Matthiola species have a higher GC content in the TTG1 gene than Arabidopsis and the closer-related Malcolmia, indicating that the GC content is rather an evolutionary than an ecological signal. A similar WD-40 repeat protein gene (containing no intron in the 3' untranslated region) with high similarity to the Arabidopsis TTG1-like (AtAN11) gene was found in Matthiola.
Dressel
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Department of General Genetics, Center of Plant Molecular Biology (ZMBP), Tübingen, Germany.
Hemleben
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D000429:Alcohol Oxidoreductases / Q000235:genetics; D000872:Anthocyanins / Q000096:biosynthesis; D029681:Arabidopsis Proteins / Q000235:genetics*; D001482:Base Composition; D001483:Base Sequence; D019607:Brassicaceae / Q000235:genetics* / Q000378:metabolism; D005419:Flavonoids / Q000096:biosynthesis; D015870:Gene Expression; D017343:Genes, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics; D017354:Point Mutation; D012639:Seeds
C106652:AN11 protein, Petunia x hybrida; D000872:Anthocyanins; D029681:Arabidopsis Proteins; D005419:Flavonoids; D010940:Plant Proteins; C121067:TTG1 protein, Arabidopsis; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase