Abstract
The maize p1 gene encodes a Myb-homologous transcription factor that regulates the flavonoid biosynthetic pathway. Alleles of the p1 gene confer a variety of pigmentation patterns in pericarp and cob glumes, including P1-rr (red pericarp/red cob), P1-wr (white pericarp/red cob), P1-rw (red pericarp/white cob), and P1-ww (white pericarp/white cob). We are interested in determining the mechanism(s) leading to these organ-specific pigmentation patterns. The P1-rr and P1-wr alleles have been cloned and characterized previously. We analyzed the genomic structure, sequence and expression patterns of the P1-rw allele. The results showed that, like P1-rr, P1-rw is a single copy gene which is linked with a second paralogous gene (p2). The P1-rw gene is highly similar to P1-rr and P1-wr in the 5' regulatory region, and in the Myb-domain coding sequence. However, preliminary results suggest that the 3' coding region of P1-rw is more similar to the maize p2 gene. Thus, the P1-rw allele may represent a new gene formed by recombination of p1 and p2.

In addition, we performed comparative analysis of maize P1 gene and its homologs, including maize P2 and P2t gene, sorghum Y1 gene, and a putative rice gene. These gene share similar gene structure and coding sequence. Strikingly, in non-coding sequence of these gene, we identified several conserved motifs, which could play important roles in gene regulation. These motifs would be the candidates for function analysis on promoter region of P1 gene.