Exceptional Chromosome Regions Workshop I



References for Arabidopsis centromer studies

Greg Copenhaver & Daphne Pruess

  1. Copenhaver, G. P., Nickel, K., Kuromori, T., Benito, M-I., Kaul, S., Lin, X., Bevan, M., Murphy, G., Harris, B., Parnell, L.D., McCombie, W.R., Martienssen, R.A., Marra, M. and Preuss, D. (1999) Genetic Definition and Sequence Analysis of Arabidopsis Centromeres. Science 286: 2468-74.
    High precision genetic mapping was used to define the regions that contain centromere functions on each natural chromosome in Arabidopsis thaliana. These regions exhibited dramatic recombinational repression and contained complex DNA surrounding large arrays of 180-bp repeats. Unexpectedly, the DNA within the centromeres was not merely structural, but also encoded several expressed genes. The regions flanking the centromeres were densely populated by repetitive elements yet experienced normal levels of recombination. The genetically defined centromeres were well conserved between Arabidopsis ecotypes but displayed limited sequence homology between different chromosomes, excluding repetitive DNA. This investigation provides a platform for dissecting the role of individual sequences in higher eukaryotic centromeres
  2. Copenhaver, G.P. and Preuss, D. (1999) Centromeres in the genomic era: Unraveling paradoxes. Curr. Op. Plant Biol. 2: 104-108.
    The centromeres of higher plants and animals share many common features, though current models fail to account for all aspects of centromere composition and function. This dilemma will likely be resolved in the next few years in Arabidopsis where robust assays for centromere function are available and the sequence of the entire genome will be determined.
  3. Copenhaver, G.P., Browne, W.E. and Preuss, D. (1998 ) Assaying genome-wide recombination and centromere functions with Arabidopsis tetrads. Proc. Natl. Acad. Sci 95:247-252.
    During meiosis, crossover events generate new allelic combinations, yet the abundance of these genetic exchanges in individual cells has not been measured previously on a genomic level. To perform a genome-wide analysis of recombination, we monitored the assortment of genetic markers in meiotic tetrads from Arabidopsis. By determining the number and distribution of crossovers in individual meiotic cells, we demonstrate i) surprisingly precise regulation of crossover number in each meiosis, ii) considerably reduced recombination along chromosomes carrying ribosomal DNA arrays, and iii) an inversely proportional relationship between recombination frequencies and chromosome size. This use of tetrad analysis also achieved precise mapping of all five Arabidopsis centromeres, localizing centromere functions in the intact chromosomes of a higher eukaryote.

Other relevant references:

  1. Copenhaver, G.P., Doelling, J.H., Gens, S.J., Pikaard, C.S. (1995) Use of RFLPs larger than 100 kbp to map the position and internal organization of the nucleolus organizer region on chromosome 2 in Arabidopsis thaliana. The Plant Journal 7(2): 273-286.
  2. Copenhaver, G.P., and Pikaard, C.S. (1996) RFLP and physical mapping with an rDNA-specific endonuclease reveals that nucleolus organizer regions of Arabidopsis thaliana adjoin the telomeres on chromosomes 2 and 4.The Plant Journal 9(2): 259-272.
  3. Copenhaver, G.P. and Pikaard, C.S. (1996) Two-dimensional RFLP analyses reveal megabase-sized clusters of rRNA gene variants in Arabidopsis thaliana, suggesting local spreading of variants as the mode for gene homogenization during concerted evolution. The Plant Journal 9(2): 273-282.

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