Steady-state transposon mutagenesis in inbred maize.

We implement a novel strategy for harnessing the power of high-copy transposons for functional analysis of the maize genome, and report behavioral features of the Mutator system in a uniform inbred background. The unique UniformMu population and database facilitate high-throughput molecular analysis of Mu-tagged mutants and gene knockouts. Key features of the population include: (i) high mutation frequencies (7% independent seed mutations) and moderation of copy number (approximately 57 total Mu elements; 1-2 MuDR copies per plant) were maintained by continuous back-crossing into a phenotypically uniform inbred background; (ii) a bz1-mum9 marker enabled selection of stable lines (loss of MuDR), inhibiting further transpositions in lines selected for molecular analysis; (iii) build-up of mutation load was prevented by screening Mu-active parents to exclude plants carrying pre-existing seed mutations.