Molecular characterization of the Abp1 5 '-flanking region in maize and the teosintes

Auxin-binding protein 1 subsp. mays (ABP1) has been suggested as a receptor mediating auxin-induced cell expansion and differentiation. In maize (Zea mays), ABP1 is encoded by a single gene, Abp1. The TATA and CAAT promoter e lements as well as the transcriptional start site were previously identifie d and all were found to be located within a transposable element (TE), Tour ist-Zm11. In this study we report the cloning and characterization of the A bp1 5'-flanking region in maize and its wild relatives, the teosintes. We p rovide evidence for insertion polymorphism corresponding to Tourist-Zm11 an d two novel TEs, Batuta and Pilgrim. Despite this polymorphic structure, th e Abp1 core promoter in maize and the teosintes is conserved, is located do wnstream of the TE insertions in the 5'-flanking region, and is TATA-less. We discuss the potential evolutionary impact of these TEs on the regulation of Abp1 gene expression.