The myb-homologous P gene controls phlobaphene pigmentation in maize floral organs by directly activating a flavonoid biosynthetic gene subset.
The maize P gene, which specifies red pigmentation of the kernel pericarp, cob, and other floral organs, has been an important model since the early days of modern genetics. Here we show that P encodes a Myb homolog that recognizes the sequence CCT/AACC, in sharp contrast with the C/TAACGG bound by vertebrate Myb proteins. P binds to and activates transcription of the A1 gene required for 3-deoxy flavonoid and phlobaphene biosynthesis, but not the Bz1 gene required for anthocyanin biosynthesis. The maize C1 gene, which also encodes a Myb homolog, activates both the A1 and Bz1 genes, but only in the presence of a basic-helix-loop-helix coactivator encoded by the maize genes R or B. These results indicate that Myb homologs can differentially regulate gene expression by binding different DNA sequences, through combinatorial interactions with other factors, or both.
Grotewold
E
E
Cold Spring Harbor Laboratory, New York 11724-2212.
Drummond
B J
BJ
Bowen
B
B
Peterson
T
T
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005419:Flavonoids / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D017343:Genes, Plant; D005809:Genes, Regulator; D008969:Molecular Sequence Data; D016296:Mutagenesis; D020626:Oncogene Proteins v-myb; D009857:Oncogenes; D010860:Pigments, Biological / Q000096:biosynthesis; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015682:Retroviridae Proteins, Oncogenic / Q000096:biosynthesis / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D014714:Vertebrates; D003313:Zea mays / Q000235:genetics* / Q000502:physiology
D004268:DNA-Binding Proteins; D005419:Flavonoids; D020626:Oncogene Proteins v-myb; C085863:P protein, Zea mays; D010860:Pigments, Biological; D010940:Plant Proteins; D015682:Retroviridae Proteins, Oncogenic