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Meiotic recombination. transposons. and genome organization in plantsHomologous meiotic recombination and transposition of mobile genetic elements are common events leading to chromosome changes in higher plants. We are using the highly recombinogenic bronze (bz) locus of maize to study meiotic recombination in plants. We have generated and analyzed rare intragenic recombinants (IGRs) from various combinations of bz mutations. The IGR chromosomes are being analyzed molecularly to determine similarities and differences between the meiotic recombination process in plants and in other model systems. such as yeast. The bz gene is a highly localized recombination hotspot in the maize genome. but unlike yeast genes. it does not show an internal gradient in recombination frequency. We are currently attempting to elucidate the basis for the extreme differences between recombination inside and immediately outside of the bz gene. Our sequence analysis of BAC clones of the bz region suggests that recombination in maize may be restricted to genes. Transposons can move from one chromosomal location to another and often insert in genes. so they can be used as gene searchers in complex genomes. We are interested not only in the biology of the maize transposon Activator (Ac) in its native and transgenic hosts. but also in the utilization of Ac as a molecular tag for gene isolation. To aid in the isolation of genes from maize and other plants that lack well-characterized transposons. we have developed reliable systems for the detection of rare transposition events. Taking advantage of Ac 's preference to transpose into genes. we are using it as a gene-searching engine in a large Ac insertion library generated as part of our Maize Genome Project. We are also producing transgenic maize plants carrying an engineered Ac that will serve as an improved gene tag in future tagging experiments. Selected PublicationsHe L, Dooner HK. (2009) Haplotype structure strongly affects recombination in a maize genetic interval polymorphic for Helitron and retrotransposon insertions. Proc Natl Acad Sci U S A. 106(21):8410-6. Li Y, Dooner HK. (2009) Excision of helitron transposons in maize. Genetics. 182(1):399-402. Huang JT, Dooner HK. (2008) Macrotransposition and other complex chromosomal restructuring in maize by closely linked transposons in direct orientation. Plant Cell. 20(8):2019-32. Dooner HK, He L. (2008) Maize genome structure variation: interplay between retrotransposon polymorphisms and genic recombination. Plant Cell. 20(2):249-58. Du C, Caronna J, He L, Dooner HK. (2008) Computational prediction and molecular confirmation of Helitron transposons in the maize genome. BMC Genomics. 9:51. Lin C, Shen B, Xu Z, Köllner TG, Degenhardt J, Dooner HK. (2008) Characterization of the monoterpene synthase gene tps26, the ortholog of a gene induced by insect herbivory in maize. Plant Physiol. 146(3):940-51. Dooner HK, Weil CF. (2007) Give-and-take: interactions between DNA transposons and their host plant genomes. Curr Opin Genet Dev. 17(6):486-92. Wang Q, Dooner HK. (2006) Remarkable variation in maize genome structure inferred from haplotype diversity at the bz locus. Proc Natl Acad Sci U S A. 103(47):17644-9. Wu XR, Chen Z, Shende A, Dooner HK, Folk WR. (2006) Visualizing bz1 missense suppression in Zea mays: an assay for monocot tRNA expression and utilization. Plant Mol Biol. 61(4-5):795-8. Messing J. Dooner HK. (2006) Organization and variability of the maize genome. Curr Opin Plant Biol. 9(2):157-63. Xu Z. Dooner HK. (2006) The maize aberrant pollen transmission 1 gene is a SABRE/KIP homolog required for pollen tube growth. Genetics. 172(2):1251-61. Lai J. Li Y. Messing J. Dooner HK. (2005) Gene movement by Helitron transposons contributes to the haplotype variability of maize. Proc Natl Acad Sci U S A. 102(25):9068-73. Xu Z. Dooner HK. (2005) Mx-rMx. a family of interacting transposons in the growing hAT superfamily of maize. Plant Cell. 17(2):375-88. Xu Z. Yan X. Maurais S. Fu H. O'Brien DG. Mottinger J. Dooner HK. (2004) Jittery. a Mutator distant relative with a paradoxical mobile Dooner. H.K. (2002). Intraspecific violation of genetic colinearity and its implications in maize. Proc. Natl. Acad. Sci. USA 99: 9573-9578. Cowperthwaite. M.. Park. W.. Xu. Z.. Yan. X. . Maurais. S. and Dooner. H.K. (2002). Use of the transposon Ac as a gene-searching engine in the maize genome. Plant Cell 14: 713-726. Dooner. H.K. (2002). Extensive interallelic polymorphisms drive meiotic recombination into a crossover pathway. Plant Cell 14:1173-1183. Fu. H.. Zheng. Z. and Dooner. H.K. (2002). Recombination rates between adjacent genic and retrotransposon regions in maize vary by two orders of magnitude. Proc. Natl. Acad. Sci. USA 99: 1082-1087. Fu. H.. Park. W.. Yan. X.. Zheng. Z.. Shen. B. and Dooner. H.K. (2001). The highly recombinogenic bz locus lies in an unusually gene-rich region of the maize genome. Proc. Natl. Acad. Sci. USA 98: 8903-8908. |
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