A Single-Base Substitution Suppresses Flower Color Mutation Caused by a Novel Miniature Inverted-Repeat Transposable Element in Gentian

Mol Genet Genomics. 2011 Dec;286(5-6):371-82. doi: 10.1007/s00438-011-0652-x. Epub 2011 Oct 15.

Abstract

We investigated the genetic basis for the derivation of pink coloration in petals from blue flowers in cultivated gentians. Using a revertant blue-flower phenotype that arose spontaneously from a pink-flowered cultivar, we sought to elucidate the molecular mechanism of flower color restoration caused by a suppressor mutation. Detailed sequencing analysis identified three novel deficient flavonoid 3',5'-hydroxylase (F3'5'H) alleles in pink-flowered gentians in addition to two mutations identified previously (Nakatsuka et al. in Mol Genet Genomics 275:231-241, 2006). Among the deficient alleles, one allele that contained a novel miniature inverted-repeat transposable element (GtMITE1) insertion in an intron of F3'5'H was shown to cause missplicing, resulting in abnormal F3'5'H transcripts and the pink-flower phenotype. The other two mutations were identified as a single-nucleotide insertion and gypsy-Ty3 retrotransposon (Tgt1) insertion within exon 1 and exon 2 of the F3'5'H gene, respectively. The blue-flowered revertant mutant contained a single-nucleotide spontaneous mutation immediately 3' of the TAA target site duplication and the GtMITE1 insertion, which caused restoration of normal splicing of F3'5'H and the normal blue-flower phenotype. Transient expression assays in gentian flowers in vivo demonstrated that normal F3'5'H splicing pattern was recovered from missplicing induced by the GtMITE1 insertion by the single-nucleotide substitution. These findings extend our knowledge of genomic evolution by transposable elements and spontaneous mutations in Gentiana species of economic and medical importance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Biological Evolution
  • Color
  • DNA Transposable Elements / genetics*
  • Flowers / genetics*
  • Genes, Plant
  • Genome, Plant
  • Gentiana / genetics*
  • Gentiana / physiology
  • Inverted Repeat Sequences / genetics*
  • Molecular Sequence Data
  • Point Mutation*

Substances

  • DNA Transposable Elements

Associated data

  • GENBANK/AB586140
  • GENBANK/AB586141
  • GENBANK/AB586142
  • GENBANK/AB618204
  • GENBANK/AB642158
  • GENBANK/AB642159
  • GENBANK/AB642160