A molecular genetic analysis of insertions in the bronze locus in maize

Abstract

We have undertaken a combined molecular and genetic analysis of the bronze (bz) locus in maize. The bz locus was isolated by a two-step approach involving sequences from the transposable elements Dissociation (Ds) and Activator (Ac). A restriction map of the bz region is presented, identifying the transcribed region and the direction of transcription. We have mapped the sites of two Ds insertions, bz-m2 (DI) and bz-m1, physically and genetically. bz-m2 (DI) is a 3.5 kb insertion in the transcribed region that appears to have arisen by an internal deletion in the 4.5 kb Ac insertion in the mutant bz-m2. bz-m1 is a 1.1 kb insert in the 5′ end of the gene. By correlating the genetic and physical maps, we have been able to orient the restriction map relative to the centromere in chromosome 9 and have obtained a rough estimate of the physical length of a unit of genetic recombination in a microregion of the maize genome.