The maize repressor-like gene intensifier1 shares homology with the r1/b1 multigene family of transcription factors and exhibits missplicing

The recessive mutation intensifier1 of maize apparently causes an overall increase in flavonoid production in the aleurone, The mechanism by which this is achieved is not understood. We have succeeded in cloning the intensifier1 gene by transposon tagging with Suppressor-mutator and found, by sequence analyses, that it shares homology with known transcription factors in the anthocyanin pathway, in particular the r1/b1 multigene family in maize. Two cDNAs and a genomic clone were completely sequenced, and together they showed that the transcripts were misspliced. The frequency of missplicing was investigated by polymerase chain reaction analyses and sequencing of the individual introns. These studies indicate that very little functional transcript was made. Indeed, missplicing may be a mechanism for reducing the levels of a transcription factor that, when present, acts as a repressor of anthocyanin biosynthesis.