GEPHE SUMMARY Print
Entry Status
Published
GepheID
GP00000224
Main curator
Martin
PHENOTYPIC CHANGE
Trait Category
Trait State in Taxon A
Iochroma calycinum - blue morphs
Trait State in Taxon B
Iochroma calycinum - white morph
Ancestral State
Taxon A
Taxonomic Status
Taxon A
Common Name
-
Synonyms
Iochroma calycinum Benth.
Rank
species
Lineage
Show more ... ophyta; Tracheophyta; Euphyllophyta; Spermatophyta; Magnoliophyta; Mesangiospermae; eudicotyledons; Gunneridae; Pentapetalae; asterids; lamiids; Solanales; Solanaceae; Solanoideae; Physaleae; Iochroma
NCBI Taxonomy ID
is Taxon A an Infraspecies?
No
Taxon B
Common Name
-
Synonyms
Iochroma calycinum Benth.
Rank
species
Lineage
Show more ... ophyta; Tracheophyta; Euphyllophyta; Spermatophyta; Magnoliophyta; Mesangiospermae; eudicotyledons; Gunneridae; Pentapetalae; asterids; lamiids; Solanales; Solanaceae; Solanoideae; Physaleae; Iochroma
NCBI Taxonomy ID
is Taxon B an Infraspecies?
No
GENOTYPIC CHANGE
Generic Gene Name
DFRA
Synonyms
dihydroflavonol 4-reductase; DIHYDROFLAVONOL 4-REDUCTASE; DIHYDROKAEMPFEROL 4-REDUCTASE; M318; MJB21.18; MJB21_18; TT3; DFR; At5g42800
Sequence Similarities
Belongs to the NAD(P)-dependent epimerase/dehydratase family. Dihydroflavonol-4-reductase subfamily.
UniProtKB
Arabidopsis thaliana
GenebankID or UniProtKB
Presumptive Null
No
Molecular Type
Aberration Type
Deletion Size
10-99 bp
Molecular Details of the Mutation
33bp (11 a.a) deletion In coding sequence
Experimental Evidence
Authors
Coburn RA; Griffin RH; Smith SD
Abstract
White forms of typically pigmented flowers are one of the most common polymorphisms in flowering plants. Although the range of genetic changes that give rise to white phenotypes is well known from model systems, few studies have identified causative mutations in natural populations.

Here we combine genetic studies, in vitro enzyme assays, and biochemical analyses to identify the mechanism underlying the loss of anthocyanin pigment production in the naturally occurring white-flowered morph of Iochroma calycinum (Solanaceae).

Comparison of anthocyanin gene sequences revealed a putative loss-of-function mutation, an 11 amino-acid deletion in dihydroflavonol 4-reductase (DFR), in the white morph. Functional assays of Dfr alleles from blue and white morphs demonstrated that this deletion results in a loss of enzymatic activity, indicating that the deletion could be solely responsible for the lack of pigment production. Consistent with this hypothesis, quantitative PCR showed no significant differences in expression of anthocyanin genes between the morphs. Also, thin layer chromatography confirmed that the white morph continues to accumulate compounds upstream of the DFR enzyme.

Collectively, these experiments indicate that the structural mutation at Dfr underlies the rare white flower morph of I. calycinum. This study is one of only a few examples where a flower color polymorphism is due to a loss-of-function mutation in the coding region of an anthocyanin enzyme. The rarity of such mutations in nature suggests that negative consequences prevent fixation across populations.

© 2015 Botanical Society of America, Inc.
Additional References
RELATED GEPHE
Related Genes
No matches found.
Related Haplotypes
No matches found.
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