title: Steady-state transposon mutagenesis in inbred maize.
abstract: 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. To create a database of genomic sequences flanking Mu insertions, selected mutant lines were analyzed by sequencing of MuTAIL PCR clone libraries. These sequences were annotated and clustered to facilitate bioinformatic subtraction of ancestral elements and identification of insertions unique to mutant lines. New insertions targeted low-copy, gene-rich sequences, and in silico mapping revealed a random distribution of insertions over the genome. Our results indicate that Mu populations differ markedly in the occurrence of Mu insertion hotspots and the frequency of suppressible mutations. We suggest that controlled MuDR copy number in UniformMu lines is a key determinant of these differences. The public database (http://uniformmu.org; http://endosperm.info) includes pedigree and phenotypic data for over 2000 independent seed mutants selected from a population of 31 548 F2 lines and integrated with analyses of 34 255 MuTAIL sequences.
authors.affiliation: Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA. drm@ufl.edu
authors.forename: Donald R
authors.initials: DR
authors.lastname: McCarty
authors.forename: Andrew Mark
authors.initials: AM
authors.lastname: Settles
authors.forename: Masaharu
authors.initials: M
authors.lastname: Suzuki
authors.forename: Bao Cai
authors.initials: BC
authors.lastname: Tan
authors.forename: Susan
authors.initials: S
authors.lastname: Latshaw
authors.forename: Tim
authors.initials: T
authors.lastname: Porch
authors.forename: Kevin
authors.initials: K
authors.lastname: Robin
authors.forename: John
authors.initials: J
authors.lastname: Baier
authors.forename: Wayne
authors.initials: W
authors.lastname: Avigne
authors.forename: Jinsheng
authors.initials: J
authors.lastname: Lai
authors.forename: Joachim
authors.initials: J
authors.lastname: Messing
authors.forename: Karen E
authors.initials: KE
authors.lastname: Koch
authors.forename: L Curtis
authors.initials: LC
authors.lastname: Hannah
mesh_terms: D001947:Breeding; D004251:DNA Transposable Elements / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D015723:Gene Library; D016254:Mutagenesis, Insertional / Q000235:genetics*; D012639:Seeds / Q000235:genetics; D003313:Zea mays / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D018744:DNA, Plant