NameHuang, Jun (author), Dooner, Hugo K (chair), Messing, Joachim (internal member), Jelenkovic, Gojko (internal member), Mckim, Kim (outside member), Rutgers University, Graduate School - New Brunswick,
DescriptionAc (Activator) is the first autonomous transposon described by McClintock. Its ability to create DSBs (Double Strand Breaks) makes it a powerful mutagen. In the presence of the Ac transposase, its non-autonomous Ds (Dissociation) counterparts are just as mutagenic. Ac and Ds are well known for creating excision footprints that lead mostly to the formation of nonfunctional alleles; less well known is their ability to generate large chromosomal rearrangements. We made use of a mutable allele bz-m39(Ac) to facilitate the selection of such rearrangements. We found Ac can give rise to Ds elements, immobilized Ac elements, adjacent sequence deletions with or without Ac excision, and fractured or one-ended Acs with either deletion or duplication of adjacent sequences. This is the first study to provide a comprehensive view of the types and frequencies of mutations, other than simple excision footprints, that can be produced at a locus by Ac-induced DSBs. Closely linked pairs of transposons, a frequent outcome of Ac/Ds transposition, are even more capable of engineering the genome than single elements. We studied the pair of transposons Ds2(DII) and Ac6067, located 6 kb apart in the bz locus in 9S, and documented the first transpositions of a macrotransposon consisting of both elements plus the intervening chromosomal segment. This transposon pair can break chromosomes at a high frequency and produce other complex rearrangements, including deletions, inversions, and reshuffling of the intertransposon segment. TE (Transposable Element) pairs are adept at restructuring chromosomes and may have been instrumental in reshaping plant genomes. The mutagenesis feature of transposons makes them a great tool to facilitate gene isolation and functional analysis. With the assistance of Ac and Mutator transposons, we characterized two maize duplicate genes, stk1 and stk2. These paralogs express only in pollen and the mature tassel, and both likely function in pollen tube growth since mutations of either one affect pollen transmission, though stk2 shows a milder effect. The double mutant combination is essentially pollen lethal. This study shows that the stk paralogs play an essential, though slightly unequal, role in pollen development.
NoteIncludes bibliographical references
Noteby Jun Huang
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.