Coloration (flowers; seeds)
Park KI; Choi JD; Hoshino A ; et al.
An intragenic tandem duplication in a transcriptional regulatory gene for anthocyanin biosynthesis c[...]
intragenic tandem duplication of 3.3 kbp of the bHLH2 gene. 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.
Published - Accepted by Curator