Germinal excisions of the maize transposon Activator do not stimulate meiotic recombination or homology-dependent repair at the bz locus

Abstract

Double-strand breaks have been implicated both in the initiation of meiotic recombination in yeast and as intermediates in the transposition process of nonreplicative transposons. Some transposons of this class, notably P of Drosophila and Tc1 of Caenorhabditis elegans, promote a form of homology-dependent premeiotic gene conversion upon excision. In this work, we have looked for evidence of an interaction between Ac transposition and meiotic recombination at the bz locus in maize. We find that the frequency of meiotic recombination between homologues is not enhanced by the presence of Ac in one of the bz heteroalleles and, conversely, that the presence of a homologous sequence in either trans (homologous chromosome) or cis (tandem duplication) does not promote conversion of the Acinsertion site. However, a tandem duplication of the bz locus may be destabilized by the insertion of Ac. We discuss possible reasons for the lack of interaction between Ac excision and homologous meiotic recombination in maize.