The P gene controls phlobaphene pigment synthesis in maize floral organs, most notably kernel pericarp and cob. To understand the molecular evolution of this regulatory gene, we are investigating the P gene in the maize relative teosinte. Using materials supplied by John Doebley, we have found apparent visible P gene expression in teosinte as a faint brown color in the tassel glume margin. It was previously reported by Ed Coe that the brown color of maize tassel glume margins was correlated with the P-specified red cob trait. Further evidence for a P gene in teosinte has been obtained by Southern hybridization, PCR, and sequencing. The Myb-homologous DNA binding domains of the maize and teosinte P genes are highly conserved. Our long-term interest is in how the tissue-specific expression of the P gene was affected by the marked changes in floral organ morphology which occurred in the development of maize from teosinte. 

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