title: A dominant point mutation in a RINGv E3 ubiquitin ligase homoeologous gene leads to cleistogamy in Brassica napus.
abstract: In the allopolyploid Brassica napus, we obtained a petal-closed flower mutation by ethyl methanesulfonate mutagenesis. Here, we report cloning and characterization of the Bn-CLG1A (CLG for cleistogamy) gene and the Bn-clg1A-1D mutant allele responsible for the cleistogamy phenotype. Bn-CLG1A encodes a RINGv E3 ubiquitin ligase that is highly conserved across eukaryotes. In the Bn-clg1A-1D mutant allele, a C-to-T transition converts a Pro at position 325 to a Leu (P325L), causing a dominant mutation leading to cleistogamy. B. napus and Arabidopsis thaliana plants transformed with a Bn-clg1A-1D allele show cleistogamous flowers, and characterization of these flowers suggests that the Bn-clg1A-1D mutation causes a pronounced negative regulation of cutin biosynthesis or loading and affects elongation or differentiation of petal and sepal cells. This results in an inhibition or a delay of petal development, leading to folded petals. A homoeologous gene (Bn-CLG1C), which shows 99.5% amino acid identity and is also constitutively and equally expressed to the wild-type Bn-CLG1A gene, was also identified. We showed that P325L is not a loss-of-function mutation and did not affect expression of Bn-clg1A-1D or Bn-CLG1C. Our findings suggest that P325L is a gain-of-function semidominant mutation, which led to either hyper- or neofunctionalization of a redundant homoeologous gene.
authors.affiliation: Unité de Recherche en Génomique Végétale Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université d'Evry Val d'Essones, Organization and Evolution of Plant Genomes, 91057 Evry cedex, France.
authors.forename: Yun-Hai
authors.initials: YH
authors.lastname: Lu
authors.forename: Dominique
authors.initials: D
authors.lastname: Arnaud
authors.forename: Harry
authors.initials: H
authors.lastname: Belcram
authors.forename: Cyril
authors.initials: C
authors.lastname: Falentin
authors.forename: Patricia
authors.initials: P
authors.lastname: Rouault
authors.forename: Nathalie
authors.initials: N
authors.lastname: Piel
authors.forename: Marie-Odile
authors.initials: MO
authors.lastname: Lucas
authors.forename: Jérémy
authors.initials: J
authors.lastname: Just
authors.forename: Michel
authors.initials: M
authors.lastname: Renard
authors.forename: Régine
authors.initials: R
authors.lastname: Delourme
authors.forename: Boulos
authors.initials: B
authors.lastname: Chalhoub
mesh_terms: D029688:Brassica napus / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation / Q000235:genetics / Q000502:physiology; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D044767:Ubiquitin-Protein Ligases