January 12-16, 2008
Town & Country Convention Center
San Diego, CA
Wolfgang Goettel , Joachim Messing
Phlobaphenes are reddish flavenoid pigments that are frequently found in male and female maize floral organs. Phlobaphene accumulation is controlled by the p1 gene, which encodes an R2R3 myb-like transcriptional activator. In contrast, the p1-paralogous gene p2 does not induce visible phlobaphene synthesis in maize tissues, although p2 and p1 gene products are virtually identical. Both p1 and p2 are thought to have arisen from a duplication event from an ancestral p gene. Various allelic forms of p1 with distinct tissue-specific and time-specific expression pattern have been collected and investigated. The epigenetically regulated P1-wr allele is characterized by colorless pericarp and red glumes. However, in presence of Ufo1, an epigenetic modifier of P1-wr, pigmentation levels in p1-expressing tissues are increased several fold. To understand the allelic diversity at the p locus in general and to gain insight in epigenetic silencing of P1-wr we sequenced and analyzed contiguous 330 kb from inbred line B73 that contain P1-wr, p2 and flanking genes. The P1-wr allele consists of multiple P1-wr repeats that are arranged in a tandem head-to-tail array. Interestingly, the P1-wr cluster is flanked by sequences that resemble p2 5’ and p2 3’ ends. Although all P1-wr repeats are structurally identical, the existence of few polymorphic sites (including transposon insertions) among P1-wr repeats facilitates the transcriptional analysis of P1-wr in presence and absence of Ufo1. The provided sequence information forms the foundation that is necessary to study allelic diversity, recombination and gene regulation at the P1-wr cluster.