Functional analysis of Antirrhinum kelloggii flavonoid 3'-hydroxylase and flavonoid 3',5'-hydroxylase genes; critical role in flower color and evolution in the genus Antirrhinum

J Plant Res. 2012 May;125(3):451-6. doi: 10.1007/s10265-011-0455-5. Epub 2011 Sep 30.

Abstract

The enzymes flavonoid 3'-hydroxylase (F3'H) and flavonoid 3',5'-hydroxylase (F3'5'H) play an important role in flower color by determining the B-ring hydroxylation pattern of anthocyanins, the major floral pigments. F3'5'H is necessary for biosynthesis of the delphinidin-based anthocyanins that confer a violet or blue color to most plants. Antirrhinum majus does not produce delphinidin and lacks violet flower colour while A. kelloggii produces violet flowers containing delphinidin. To understand the cause of this inter-specific difference in the Antirrhinum genus, we isolated one F3'H and two F3'5'H homologues from the A. kelloggii petal cDNA library. Their amino acid sequences showed high identities to F3'Hs and F3'5'Hs of closely related species. Transgenic petunia expressing these genes had elevated amounts of cyanidin and delphinidin respectively, and flower color changes in the transgenics reflected the type of accumulated anthocyanidins. The results indicate that the homologs encode F3'H and F3'5'H, respectively, and that the ancestor of A. majus lost F3'5'H activity after its speciation from the ancestor of A. kelloggii.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Anthocyanins / metabolism*
  • Antirrhinum / enzymology*
  • Antirrhinum / genetics*
  • Biosynthetic Pathways
  • Cytochrome P-450 Enzyme System / genetics*
  • Cytochrome P-450 Enzyme System / metabolism*
  • Evolution, Molecular
  • Flowers / enzymology*
  • Flowers / genetics*
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Genetic Speciation
  • Petunia
  • Phylogeny
  • Pigments, Biological / biosynthesis
  • Plants, Genetically Modified / metabolism
  • Species Specificity

Substances

  • Anthocyanins
  • Pigments, Biological
  • Cytochrome P-450 Enzyme System
  • flavonoid 3',5'-hydroxylase