RRC ID 722
Author Park KI, Choi JD, Hoshino A, Morita Y, Iida S.
Title An intragenic tandem duplication in a transcriptional regulatory gene for anthocyanin biosynthesis confers pale-colored flowers and seeds with fine spots in Ipomoea tricolor.
Journal Plant J.
Abstract While the wild-type morning glory (Ipomoea tricolor) displays bright-blue flowers and dark-brown seeds, its spontaneous mutant, Blue Star, carrying the mutable ivory seed-variegated (ivs-v) allele, exhibits pale-blue flowers with a few fine blue spots and ivory seeds with tiny dark-brown spots. The mutable allele is caused by an intragenic tandem duplication of 3.3 kbp within a gene for transcriptional activator containing a basic helix-loop-helix (bHLH) DNA-binding motif. Each of the tandem repeats is flanked by a 3-bp sequence AAT, indicating that the 3-bp microhomology is used to generate the tandem duplication. The transcripts in the pale-blue flower buds of the mutant contain an internal 583-bp tandem duplication that results in the production of a truncated polypeptide lacking the bHLH domain. The mRNA accumulation of most of the structural genes encoding enzymes for anthocyanin biosynthesis in the flower buds of the mutant was significantly reduced. The transcripts identical to the wild-type mRNAs for the transcriptional activator were present abundantly in blue spots of the variegated flowers, whereas the transcripts containing the 583-bp tandem duplication were predominant in the pale-blue background of the same flowers. The flower and seed variegations studied here are likely to be caused by somatic homologous recombination between an intragenic tandem duplication in the gene encoding a bHLH transcriptional activator for anthocyanin biosynthesis, whereas various flower variegations are reported to be caused by excision of DNA transposons inserted into pigmentation genes.
Volume 38(5)
Pages 840-9
Published 2004-6
DOI 10.1111/j.1365-313X.2004.02098.x
PMID 15144384
MeSH Anthocyanins / biosynthesis Base Sequence Cloning, Molecular DNA Transposable Elements DNA, Plant / genetics Flowers / genetics* Gene Expression Regulation, Plant / genetics* Genome, Plant Ipomoea / genetics* Molecular Sequence Data Pigmentation RNA, Messenger / genetics RNA, Plant / genetics Seeds / genetics Seeds / physiology Transcription, Genetic / genetics*
IF 5.775
Times Cited 32
Morning Glory AK401 AK404