RRC ID 2171
Author Park KI, Ishikawa N, Morita Y, Choi JD, Hoshino A, Iida S.
Title A bHLH regulatory gene in the common morning glory, Ipomoea purpurea, controls anthocyanin biosynthesis in flowers, proanthocyanidin and phytomelanin pigmentation in seeds, and seed trichome formation.
Journal Plant J
Abstract The transcriptional regulators for anthocyanin pigmentation include proteins containing R2R3-MYB domains, bHLH domains and conserved WD40 repeats, and their interactions determine the set of genes to be expressed. Spontaneous ivory seed (ivs) mutants of Ipomoea purpurea displaying pale pigmented flowers and ivory seeds are caused by insertions of DNA transposons into the bHLH2 gene that encodes a bHLH transcriptional regulator. A partial reduction in the expression of all structural genes encoding enzymes for anthocyanin biosynthesis was observed in the young flower buds of these ivs mutants. The DFR-B and ANS transcripts were completely abolished in the ivs seed coats, whereas the early biosynthetic genes for flavonol biosynthesis remained active. The production and accumulation of both proanthocyanidin and phytomelanin pigments in the ivory seed coats were drastically reduced. Moreover, the unbranched trichomes in the ivory seeds were smaller in size and fewer in number than those in the wild-type dark-brown seeds, and the surface of the epidermis without trichomes in the dark-brown seeds looked rougher, due to the protruding tangential walls, than that in the ivory seeds. Although the I. purpurea bHLH2 gene is the most closely related to the petunia AN1 gene, whose mutation is known to confer white flowers and to be deficient in acidification of their vacuoles, the vacuolar alkalization in the epidermal flower limbs of I. purpurea ivs mutants appears to occur normally. These results are discussed with regard to the function of bHLH transcriptional regulators controlling flower and seed pigmentation as well as other epidermal traits.
Volume 49(4)
Pages 641-54
Published 2007-2-1
DOI 10.1111/j.1365-313X.2006.02988.x
PMID 17270013
MeSH Anthocyanins / biosynthesis Base Sequence Basic Helix-Loop-Helix Transcription Factors / genetics Basic Helix-Loop-Helix Transcription Factors / physiology* Blotting, Northern Flowers / genetics Flowers / growth & development Flowers / metabolism* Gene Expression Regulation, Plant Ipomoea / genetics Ipomoea / growth & development Ipomoea / metabolism* Melanins / biosynthesis Models, Biological Models, Genetic Molecular Sequence Data Mutation Pigments, Biological / biosynthesis* Plant Proteins / genetics Plant Proteins / metabolism Proanthocyanidins / biosynthesis Reverse Transcriptase Polymerase Chain Reaction Seeds / genetics Seeds / growth & development Seeds / metabolism*
IF 6.141
Times Cited 68
Morning Glory AK311 AK313 AK314 AK316 AK317 AK321 AK322 AK333